Module: MilkTea::LowererAsync

Included in:
Lowerer
Defined in:
lib/milk_tea/core/lowering/async.rb,
lib/milk_tea/core/lowering/async/analysis.rb,
lib/milk_tea/core/lowering/async/lowering.rb,
lib/milk_tea/core/lowering/async/normalization.rb

Instance Method Summary collapse

Instance Method Details

#analyze_async_function(binding, statements) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/analysis.rb', line 5

def analyze_async_function(binding, statements)
  env = empty_env
  void_ptr = pointer_to(@ctx.types.fetch("void"))
  wake_type = Types::Registry.function(
    nil,
    params: [Types::Registry.parameter("frame", void_ptr)],
    return_type: @ctx.types.fetch("void"),
  )
  param_fields = {}
  local_fields = {}
  await_fields = {}
  await_counter = 0

  binding.body_params.each do |param_binding|
    pointer = binding.type.receiver_type && binding.type.receiver_editable && param_binding.name == "this"
    field_type = pointer ? pointer_to(param_binding.type) : param_binding.type
    field_name = "param_#{param_binding.name}"
    param_fields[param_binding.name] = {
      field_name:,
      type: field_type,
      param_type: param_binding.type,
      mutable: param_binding.mutable,
      pointer:,
    }
    env[:scopes].last[param_binding.name] = local_binding(
      type: param_binding.type,
      linkage_name: field_name,
      mutable: param_binding.mutable,
      pointer:,
    )
  end
  env[:return_context] = {
    return_type: binding.body_return_type,
    active_defers: [],
    local_defers: [],
    allow_return: true,
  }

  await_counter = analyze_async_statements!(statements, await_counter, env, param_fields, local_fields, await_fields)

  {
    task_type: binding.type.return_type,
    result_type: binding.body_return_type,
    void_ptr:,
    wake_type:,
    param_fields:,
    local_fields:,
    await_fields:,
    format_str_fields: {},
  }
end

#analyze_async_statements!(statements, await_counter, env, param_fields, local_fields, await_fields) ⇒ Object

Recursively scan nested statement bodies for await slots, assigning state IDs. Returns the updated await_counter.



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# File 'lib/milk_tea/core/lowering/async/analysis.rb', line 59

def analyze_async_statements!(statements, await_counter, env, param_fields, local_fields, await_fields)
  statements.each do |statement|
    case statement
    when AST::LocalDecl
      type, storage_type = async_local_decl_types(statement, env:)
      local_field_key = async_local_decl_field_key(statement)
      local_fields[local_field_key] ||= { field_name: async_local_decl_field_name(statement), type:, storage_type:, mutable: statement.kind == :var }
      if statement.value.is_a?(AST::AwaitExpr)
        await_fields[statement.value.object_id] = build_async_await_field_info(statement.value, await_counter, env:, param_fields:, local_fields:)
        await_counter += 1
      end
      if bind_let_else_local?(statement)
        env[:scopes].last[statement.name] = local_binding(
          type:,
          storage_type:,
          linkage_name: statement.name,
          mutable: statement.kind == :var,
          pointer: false,
          const_value: statement.else_body ? nil : statement.kind == :let && statement.value ? compile_time_const_value(statement.value, env:) : nil,
        )
      end
      await_counter = analyze_async_statements!(statement.else_body, await_counter, env, param_fields, local_fields, await_fields) if statement.else_body
    when AST::Assignment
      if statement.value.is_a?(AST::AwaitExpr)
        await_fields[statement.value.object_id] = build_async_await_field_info(statement.value, await_counter, env:, param_fields:, local_fields:)
        await_counter += 1
      end
    when AST::ExpressionStmt
      if statement.expression.is_a?(AST::AwaitExpr)
        await_fields[statement.expression.object_id] = build_async_await_field_info(statement.expression, await_counter, env:, param_fields:, local_fields:)
        await_counter += 1
      end
    when AST::ReturnStmt
      if statement.value&.is_a?(AST::AwaitExpr)
        await_fields[statement.value.object_id] = build_async_await_field_info(statement.value, await_counter, env:, param_fields:, local_fields:)
        await_counter += 1
      end
    when AST::IfStmt
      statement.branches.each do |branch|
        await_counter = analyze_async_statements!(branch.body, await_counter, env, param_fields, local_fields, await_fields)
      end
      await_counter = analyze_async_statements!(statement.else_body, await_counter, env, param_fields, local_fields, await_fields) if statement.else_body
    when AST::WhileStmt
      await_counter = analyze_async_statements!(statement.body, await_counter, env, param_fields, local_fields, await_fields)
    when AST::ForStmt
      if range_iterable?(statement.iterable)
        loop_type = infer_range_loop_type(statement.iterable, env:)
        local_fields[statement.name] ||= { field_name: "local_#{statement.name}", type: loop_type, storage_type: loop_type, mutable: true }
        stop_field_name = "local_#{statement.name}_stop"
        local_fields[stop_field_name] ||= { field_name: stop_field_name, type: loop_type, storage_type: loop_type, mutable: true }
      else
        statement.bindings.each_with_index do |binding, index|
          iterable_type = infer_expression_type(statement.iterables[index], env:)
          element_type = collection_loop_type(iterable_type)
          binding_type = collection_loop_binding_type(iterable_type, element_type) || element_type
          local_fields[binding.name] ||= { field_name: "local_#{binding.name}", type: binding_type, storage_type: binding_type, mutable: true }
          iterable_field_name = async_collection_iterable_field_name(statement, index)
          iterable_field_key = async_collection_iterable_field_key(statement, index)
          local_fields[iterable_field_key] ||= { field_name: iterable_field_name, type: iterable_type, storage_type: iterable_type, mutable: true }
        end
        index_field_name = async_collection_index_field_name(statement)
        index_field_key = async_collection_index_field_key(statement)
        local_fields[index_field_key] ||= { field_name: index_field_name, type: @ctx.types.fetch("ptr_uint"), storage_type: @ctx.types.fetch("ptr_uint"), mutable: true }
      end
      await_counter = analyze_async_statements!(statement.body, await_counter, env, param_fields, local_fields, await_fields)
    when AST::MatchStmt
      scrutinee_type = infer_expression_type(statement.expression, env:)
      statement.arms.each do |arm|
        arm_env = duplicate_env(env)
        bind_async_variant_match_arm_env!(arm_env, scrutinee_type, arm)
        arm_await_count = await_counter
        await_counter = analyze_async_statements!(arm.body, await_counter, arm_env, param_fields, local_fields, await_fields)
        if arm.binding_name && await_counter > arm_await_count
          field_key = async_match_binding_field_key(arm)
          unless local_fields.key?(field_key)
            arm_name = variant_match_arm_name_from_pattern(arm.pattern)
            if arm_name
              arm_binding = arm_env[:scopes].last[arm.binding_name]
              payload_type = arm_binding && arm_binding[:type]
              if payload_type
                local_fields[field_key] = { field_name: async_match_binding_field_name(arm), type: payload_type, storage_type: payload_type, mutable: false }
              end
            end
          end
        end
      end
    when AST::UnsafeStmt
      await_counter = analyze_async_statements!(statement.body, await_counter, env, param_fields, local_fields, await_fields)
    when AST::DeferStmt
      if statement.body
        cleanup_env = duplicate_env(env)
        cleanup_env[:return_context] = cleanup_env[:return_context]&.merge(allow_return: false)
        await_counter = analyze_async_statements!(statement.body, await_counter, cleanup_env, param_fields, local_fields, await_fields)
      end
      if statement.expression.is_a?(AST::AwaitExpr)
        await_fields[statement.expression.object_id] = build_async_await_field_info(statement.expression, await_counter, env:, param_fields:, local_fields:)
        await_counter += 1
      end
    else
      nil
    end
  end
  await_counter
end

#ast_type_ref_for(type) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/normalization.rb', line 367

def ast_type_ref_for(type)
  case type
  when Types::Primitive
    AST::TypeRef.new(name: AST::QualifiedName.new(parts: [type.name]), arguments: [], nullable: false)
  when Types::Nullable
    inner = ast_type_ref_for(type.base)
    raise LoweringError.new("nullable annotation is only valid for named/generic types", line: 0, column: 0, path: @ctx.current_analysis_path) unless inner.is_a?(AST::TypeRef)

    AST::TypeRef.new(name: inner.name, arguments: inner.arguments, nullable: true)
  when Types::GenericInstance
    AST::TypeRef.new(
      name: AST::QualifiedName.new(parts: type.name.split(".")),
      arguments: type.arguments.map do |argument|
        if argument.is_a?(Types::LiteralTypeArg)
          AST::TypeArgument.new(value: AST::IntegerLiteral.new(lexeme: argument.value.to_s, value: argument.value))
        else
          AST::TypeArgument.new(value: ast_type_ref_for(argument))
        end
      end,
      nullable: false,
    )
  when Types::Span
    AST::TypeRef.new(name: AST::QualifiedName.new(parts: ["span"]), arguments: [AST::TypeArgument.new(value: ast_type_ref_for(type.element_type))], nullable: false)
  when Types::Task
    AST::TypeRef.new(name: AST::QualifiedName.new(parts: ["Task"]), arguments: [AST::TypeArgument.new(value: ast_type_ref_for(type.result_type))], nullable: false)
  when Types::TypeVar
    AST::TypeRef.new(name: AST::QualifiedName.new(parts: [type.name]), arguments: [], nullable: false)
  when Types::StructInstance
    base_parts = type.module_name ? type.module_name.split(".") + [type.name] : [type.name]
    AST::TypeRef.new(
      name: AST::QualifiedName.new(parts: base_parts),
      arguments: type.arguments.map do |argument|
        if argument.is_a?(Types::LiteralTypeArg)
          AST::TypeArgument.new(value: AST::IntegerLiteral.new(lexeme: argument.value.to_s, value: argument.value))
        else
          AST::TypeArgument.new(value: ast_type_ref_for(argument))
        end
      end,
      nullable: false,
    )
  when Types::Struct, Types::Union, Types::Opaque, Types::Enum, Types::Flags
    parts = type.module_name ? type.module_name.split(".") + [type.name] : [type.name]
    AST::TypeRef.new(name: AST::QualifiedName.new(parts: parts), arguments: [], nullable: false)
  when Types::Function
    AST::FunctionType.new(
      params: type.params.each_with_index.map { |param, i| AST::Param.new(name: param.name || "p#{i}", type: ast_type_ref_for(param.type)) },
      return_type: ast_type_ref_for(type.return_type),
    )
  when Types::Proc
    AST::ProcType.new(
      params: type.params.each_with_index.map { |param, i| AST::Param.new(name: param.name || "p#{i}", type: ast_type_ref_for(param.type)) },
      return_type: ast_type_ref_for(type.return_type),
    )
  else
    raise LoweringError.new("unsupported type for AST normalization #{type.class.name}", line: 0, column: 0, path: @ctx.current_analysis_path)
  end
end

#async_bind_local!(env, name, field_info) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 658

def async_bind_local!(env, name, field_info)
  current_actual_scope(env[:scopes])[name] = local_binding(
    type: field_info[:type],
    storage_type: field_info[:storage_type],
    linkage_name: async_frame_field_c_name(field_info[:field_name]),
    mutable: field_info[:mutable],
    pointer: false,
  )
end

#async_collection_index_field_key(statement) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/analysis.rb', line 189

def async_collection_index_field_key(statement)
  "__async_for_index_#{statement.line}"
end

#async_collection_index_field_name(statement) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/analysis.rb', line 193

def async_collection_index_field_name(statement)
  "for_index_#{statement.line}"
end

#async_collection_iterable_field_key(statement, index = 0) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/analysis.rb', line 181

def async_collection_iterable_field_key(statement, index = 0)
  "__async_for_iterable_#{statement.line}_#{index}"
end

#async_collection_iterable_field_name(statement, index = 0) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/analysis.rb', line 185

def async_collection_iterable_field_name(statement, index = 0)
  "for_iterable_#{statement.line}_#{index}"
end

#async_complete_statements(frame_expr:, raw_frame_expr:, async_info:, value:, result_already_stored: false) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1282

def async_complete_statements(frame_expr:, raw_frame_expr:, async_info:, value:, result_already_stored: false)
  lowered = []

  if async_info[:result_type] != @ctx.types.fetch("void") && !result_already_stored
    lowered << IR::Assignment.new(
      target: async_frame_field_expression(frame_expr, "result", async_info[:result_type]),
      operator: "=",
      value: value,
    )
  end

  lowered << IR::Assignment.new(
    target: async_frame_field_expression(frame_expr, "ready", @ctx.types.fetch("bool")),
    operator: "=",
    value: IR::BooleanLiteral.new(value: true, type: @ctx.types.fetch("bool")),
  )

  waiter_frame_field = async_frame_field_expression(frame_expr, "waiter_frame", async_info[:void_ptr])
  lowered << IR::IfStmt.new(
    condition: IR::Binary.new(
      operator: "!=",
      left: waiter_frame_field,
      right: IR::NullLiteral.new(type: async_info[:void_ptr]),
      type: @ctx.types.fetch("bool"),
    ),
    then_body: [
      IR::LocalDecl.new(
        name: "waiter_frame",
        linkage_name: "__mt_waiter_frame",
        type: async_info[:void_ptr],
        value: waiter_frame_field,
      ),
      IR::Assignment.new(
        target: waiter_frame_field,
        operator: "=",
        value: IR::NullLiteral.new(type: async_info[:void_ptr]),
      ),
      IR::ExpressionStmt.new(
        expression: IR::Call.new(
          callee: async_frame_field_expression(frame_expr, "waiter", async_info[:wake_type]),
          arguments: [IR::Name.new(name: "__mt_waiter_frame", type: async_info[:void_ptr], pointer: false)],
          type: @ctx.types.fetch("void"),
        ),
      ),
      IR::ReturnStmt.new(value: nil),
    ],
    else_body: nil,
  )
  lowered << IR::ReturnStmt.new(value: nil)
  lowered
end

#async_expression_contains_await?(expression) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/lowering/async/normalization.rb', line 425

def async_expression_contains_await?(expression)
  case expression
  when AST::AwaitExpr
    true
  when AST::Call, AST::Specialization
    async_expression_contains_await?(expression.callee) || expression.arguments.any? { |argument| async_expression_contains_await?(argument.value) }
  when AST::UnaryOp
    async_expression_contains_await?(expression.operand)
  when AST::BinaryOp
    async_expression_contains_await?(expression.left) || async_expression_contains_await?(expression.right)
  when AST::IfExpr
    async_expression_contains_await?(expression.condition) || async_expression_contains_await?(expression.then_expression) || async_expression_contains_await?(expression.else_expression)
  when AST::MatchExpr
    async_expression_contains_await?(expression.expression) || expression.arms.any? { |arm| async_expression_contains_await?(arm.pattern) || async_expression_contains_await?(arm.value) }
  when AST::UnsafeExpr
    async_expression_contains_await?(expression.expression)
  when AST::MemberAccess
    async_expression_contains_await?(expression.receiver)
  when AST::IndexAccess
    async_expression_contains_await?(expression.receiver) || async_expression_contains_await?(expression.index)
  when AST::FormatString
    expression.parts.any? { |part| part.is_a?(AST::FormatExprPart) && async_expression_contains_await?(part.expression) }
  else
    false
  end
end

#async_frame_cast_declaration(frame_type, async_info) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 668

def async_frame_cast_declaration(frame_type, async_info)
  IR::LocalDecl.new(
    name: async_frame_local_name,
    linkage_name: async_frame_local_name,
    type: pointer_to(frame_type),
    value: IR::Cast.new(
      target_type: pointer_to(frame_type),
      expression: IR::Name.new(name: async_frame_raw_name, type: async_info[:void_ptr], pointer: false),
      type: pointer_to(frame_type),
    ),
  )
end

#async_frame_field_c_name(field_name) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 689

def async_frame_field_c_name(field_name)
  "#{async_frame_local_name}->#{field_name}"
end

#async_frame_field_expression(frame_expr, field_name, field_type) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 697

def async_frame_field_expression(frame_expr, field_name, field_type)
  IR::Member.new(receiver: frame_expr, member: field_name, type: field_type)
end

#async_frame_local_name ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 681

def async_frame_local_name
  "__mt_frame"
end

#async_frame_raw_name ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 685

def async_frame_raw_name
  "__mt_frame_raw"
end

#async_local_decl_field_key(statement) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1390

def async_local_decl_field_key(statement)
  return "__discard_#{statement.line}" if statement.name == "_"

  statement.name
end

#async_local_decl_field_name(statement) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1396

def async_local_decl_field_name(statement)
  return "local_discard_#{statement.line}" if statement.name == "_"

  "local_#{statement.name}"
end

#async_local_decl_types(statement, env:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/analysis.rb', line 164

def async_local_decl_types(statement, env:)
  storage_type = if statement.else_body
                   infer_expression_type(statement.value, env:)
                 elsif statement.type
                   resolve_type_ref(statement.type)
                 else
                   infer_expression_type(statement.value, env:)
                 end
  type = if statement.else_body
           statement.type ? resolve_type_ref(statement.type) : let_else_success_type(storage_type)
         else
           storage_type
         end

  [type, storage_type]
end

#async_main_runtime_callee_name(function_name, type_arguments: []) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 96

def async_main_runtime_callee_name(function_name, type_arguments: [])
  binding = analysis_for_module("std.async").functions.fetch(function_name)
  binding = binding.owner.instantiate_function_binding(binding, type_arguments) if type_arguments.any?
  function_binding_c_name(binding, module_name: binding.owner.module_name)
end

#async_match_binding_field_key(arm) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1402

def async_match_binding_field_key(arm)
  @async_binding_counter ||= 0
  @async_binding_counter += 1
  "match_binding_#{@async_binding_counter}"
end

#async_match_binding_field_name(arm) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1408

def async_match_binding_field_name(arm)
  "local_match_binding_#{@async_binding_counter}"
end

#async_resume_env_for(async_info) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 645

def async_resume_env_for(async_info)
  env = empty_env
  async_info[:param_fields].each do |name, field_info|
    env[:scopes].last[name] = local_binding(
      type: field_info[:pointer] ? pointee_type(field_info[:type]) : field_info[:type],
      linkage_name: async_frame_field_c_name(field_info[:field_name]),
      mutable: field_info[:mutable],
      pointer: field_info[:pointer],
    )
  end
  env
end

#async_return_context(return_type:, active_defers:, local_defers:, frame_expr:, raw_frame_expr:, async_info:, allow_return: true) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1270

def async_return_context(return_type:, active_defers:, local_defers:, frame_expr:, raw_frame_expr:, async_info:, allow_return: true)
  {
    return_type:,
    active_defers:,
    local_defers:,
    allow_return:,
    frame_expr:,
    raw_frame_expr:,
    async_info:,
  }
end

#async_state_label(resume_linkage_name, state) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 693

def async_state_label(resume_linkage_name, state)
  "#{resume_linkage_name}_state_#{state}"
end

#async_task_call(task_expr, task_type, member, arguments, return_type) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 705

def async_task_call(task_expr, task_type, member, arguments, return_type)
  IR::Call.new(
    callee: IR::Member.new(receiver: task_expr, member:, type: task_type.field(member)),
    arguments:,
    type: return_type,
  )
end

#async_task_frame_expression(task_expr, task_type) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 701

def async_task_frame_expression(task_expr, task_type)
  IR::Member.new(receiver: task_expr, member: "frame", type: task_type.field("frame"))
end

#async_variant_match_arm_binding(arm, scrutinee_expr, scrutinee_type, env:, frame_expr: nil, local_fields: nil) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1334

def async_variant_match_arm_binding(arm, scrutinee_expr, scrutinee_type, env:, frame_expr: nil, local_fields: nil)
  arm_env = duplicate_env(env)
  binding_decl = nil

  if arm.binding_name && !wildcard_arm_pattern?(arm.pattern)
    arm_name = variant_match_arm_name_from_pattern(arm.pattern)
    if arm_name && scrutinee_type.has_payload?(arm_name)
      fields = scrutinee_type.arm(arm_name)
      payload_type = Types::VariantArmPayload.new(scrutinee_type, arm_name, fields)

      field_key = async_match_binding_field_key(arm)
      field_info = local_fields&.fetch(field_key, nil)
      if field_info && frame_expr
        target = async_frame_field_expression(frame_expr, field_info[:field_name], field_info[:storage_type])
        binding_c = async_frame_field_c_name(field_info[:field_name])
        arm_env[:scopes].last[arm.binding_name] = local_binding(type: payload_type, linkage_name: binding_c, mutable: false, pointer: false)
        data_expr = IR::Member.new(receiver: scrutinee_expr, member: "data", type: nil)
        arm_expr = IR::Member.new(receiver: data_expr, member: arm_name, type: payload_type)
        binding_decl = IR::Assignment.new(target:, operator: "=", value: arm_expr)
      else
        data_expr = IR::Member.new(receiver: scrutinee_expr, member: "data", type: nil)
        arm_expr = IR::Member.new(receiver: data_expr, member: arm_name, type: payload_type)
        binding_c = c_local_name(arm.binding_name)
        arm_env[:scopes].last[arm.binding_name] = local_binding(type: payload_type, linkage_name: binding_c, mutable: false, pointer: false)
        binding_decl = IR::LocalDecl.new(name: arm.binding_name, linkage_name: binding_c, type: payload_type, value: arm_expr)
      end
    end
  end

  [arm_env, binding_decl]
end

#bind_async_variant_match_arm_env!(arm_env, scrutinee_type, arm) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1366

def bind_async_variant_match_arm_env!(arm_env, scrutinee_type, arm)
  return unless scrutinee_type.is_a?(Types::Variant)
  return unless arm.binding_name && !wildcard_arm_pattern?(arm.pattern)

  arm_name = variant_match_arm_name_from_pattern(arm.pattern)
  return unless arm_name && scrutinee_type.has_payload?(arm_name)

  fields = scrutinee_type.arm(arm_name)
  payload_type = Types::VariantArmPayload.new(scrutinee_type, arm_name, fields)
  arm_env[:scopes].last[arm.binding_name] = local_binding(type: payload_type, linkage_name: c_local_name(arm.binding_name), mutable: true, pointer: false)
end

#build_async_await_field_info(await_expression, await_counter, env:, param_fields:, local_fields:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/analysis.rb', line 197

def build_async_await_field_info(await_expression, await_counter, env:, param_fields:, local_fields:)
  task_expression = await_expression.expression
  reused_field_name = reusable_async_await_task_field_name(task_expression, param_fields:, local_fields:)
  {
    field_name: reused_field_name || "await_#{await_counter}",
    task_type: infer_expression_type(task_expression, env:),
    result_type: infer_expression_type(await_expression, env:),
    state: await_counter + 1,
    reuse_existing_storage: !reused_field_name.nil?,
  }
end

#build_async_cancel_function(frame_type, cancel_linkage_name, async_info) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 503

def build_async_cancel_function(frame_type, cancel_linkage_name, async_info)
  frame_expr = IR::Name.new(name: async_frame_local_name, type: pointer_to(frame_type), pointer: false)

  body = [async_frame_cast_declaration(frame_type, async_info)]

  ready_expr = async_frame_field_expression(frame_expr, "ready", @ctx.types.fetch("bool"))
  if_ready_return = IR::IfStmt.new(
    condition: ready_expr,
    then_body: [IR::ReturnStmt.new(value: nil)],
    else_body: nil,
  )
  body << if_ready_return

  cancelled_assign = IR::Assignment.new(
    target: async_frame_field_expression(frame_expr, "cancelled", @ctx.types.fetch("bool")),
    operator: "=",
    value: IR::BooleanLiteral.new(value: true, type: @ctx.types.fetch("bool")),
  )
  body << IR::ExpressionStmt.new(expression: cancelled_assign)

  cancel_stmts = []
  async_info[:await_fields].each_value do |field_info|
    task_field_expr = async_frame_field_expression(frame_expr, field_info[:field_name], field_info[:task_type])
    task_frame_expr = async_task_frame_expression(task_field_expr, field_info[:task_type])
    cancel_call = IR::ExpressionStmt.new(
      expression: async_task_call(task_field_expr, field_info[:task_type], "cancel", [task_frame_expr], @ctx.types.fetch("void")),
    )
    release_call = IR::ExpressionStmt.new(
      expression: async_task_call(task_field_expr, field_info[:task_type], "release", [task_frame_expr], @ctx.types.fetch("void")),
    )
    cancel_member_expr = IR::Member.new(receiver: task_field_expr, member: "cancel", type: async_info[:task_type].field("cancel"))
    cancel_stmts << IR::IfStmt.new(
      condition: task_frame_expr,
      then_body: [
        IR::IfStmt.new(
          condition: cancel_member_expr,
          then_body: [cancel_call],
          else_body: nil,
        ),
        release_call,
      ],
      else_body: nil,
    )
  end
  body.concat(cancel_stmts) if cancel_stmts.any?

  async_info[:param_fields].each_value do |field_info|
    next if field_info[:pointer]
    next unless contains_proc_storage_type?(field_info[:type])

    field_expr = async_frame_field_expression(frame_expr, field_info[:field_name], field_info[:type])
    body.concat(lower_async_frame_proc_release_statements(field_expr, field_info[:type]))
  end

  async_info[:local_fields].each_value do |field_info|
    next unless contains_proc_storage_type?(field_info[:storage_type])

    field_expr = async_frame_field_expression(frame_expr, field_info[:field_name], field_info[:storage_type])
    body.concat(lower_async_frame_proc_release_statements(field_expr, field_info[:storage_type]))
  end

  (async_info[:format_str_fields] || {}).each_key do |field_name|
    field_expr = async_frame_field_expression(frame_expr, field_name, @ctx.types.fetch("str"))
    body << IR::ExpressionStmt.new(
      expression: IR::Call.new(
        callee: "mt_format_str_release",
        arguments: [field_expr],
        type: @ctx.types.fetch("void"),
      ),
    )
  end

  async_info[:param_fields].each_value do |field_info|
    next unless field_info[:pointer]

    param_expr = async_frame_field_expression(frame_expr, field_info[:field_name], field_info[:type])
    body << IR::ExpressionStmt.new(
      expression: IR::Call.new(callee: "mt_async_free", arguments: [param_expr], type: @ctx.types.fetch("void")),
    )
  end

  ready_assign = IR::Assignment.new(
    target: async_frame_field_expression(frame_expr, "ready", @ctx.types.fetch("bool")),
    operator: "=",
    value: IR::BooleanLiteral.new(value: true, type: @ctx.types.fetch("bool")),
  )
  body << IR::ExpressionStmt.new(expression: ready_assign)

  waiter_frame_expr = async_frame_field_expression(frame_expr, "waiter_frame", async_info[:void_ptr])
  wake_stmts = [
    IR::ExpressionStmt.new(
      expression: IR::Assignment.new(
        target: async_frame_field_expression(frame_expr, "waiter_frame", async_info[:void_ptr]),
        operator: "=",
        value: IR::NullLiteral.new(type: async_info[:void_ptr]),
      ),
    ),
    IR::ExpressionStmt.new(
      expression: IR::Call.new(
        callee: IR::Name.new(name: async_frame_field_c_name("waiter"), type: async_info[:wake_type], pointer: false),
        arguments: [waiter_frame_expr],
        type: @ctx.types.fetch("void"),
      ),
    ),
  ]
  body << IR::IfStmt.new(
    condition: waiter_frame_expr,
    then_body: wake_stmts,
    else_body: nil,
  )

  body << IR::ReturnStmt.new(value: nil)

  IR::Function.new(
    name: "#{cancel_linkage_name}_fn",
    linkage_name: cancel_linkage_name,
    params: [IR::Param.new(name: "frame", linkage_name: async_frame_raw_name, type: async_info[:void_ptr], pointer: false)],
    return_type: @ctx.types.fetch("void"),
    body:,
    entry_point: false,
  )
end

#build_async_constructor_function(binding, decl, frame_type, constructor_linkage_name, resume_linkage_name, ready_linkage_name, set_waiter_linkage_name, release_linkage_name, take_result_linkage_name, cancel_linkage_name, async_info) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 262

def build_async_constructor_function(binding, decl, frame_type, constructor_linkage_name, resume_linkage_name, ready_linkage_name, set_waiter_linkage_name, release_linkage_name, take_result_linkage_name, cancel_linkage_name, async_info)
  params = []
  body = []
  frame_pointer_type = pointer_to(frame_type)
  frame_expr = IR::Name.new(name: async_frame_local_name, type: frame_pointer_type, pointer: false)
  raw_frame_expr = IR::Cast.new(target_type: async_info[:void_ptr], expression: frame_expr, type: async_info[:void_ptr])

  body << IR::LocalDecl.new(
    name: async_frame_local_name,
    linkage_name: async_frame_local_name,
    type: frame_pointer_type,
    value: IR::Cast.new(
      target_type: frame_pointer_type,
      expression: IR::Call.new(
        callee: "mt_async_alloc",
        arguments: [IR::SizeofExpr.new(target_type: frame_type, type: @ctx.types.fetch("ptr_uint"))],
        type: async_info[:void_ptr],
      ),
      type: frame_pointer_type,
    ),
  )

  binding.body_params.each do |param_binding|
    field_info = async_info[:param_fields].fetch(param_binding.name)
    field_type = field_info[:type]
    param_type = field_info[:param_type]
    linkage_name = c_local_name(param_binding.name)
    input_linkage_name = array_type?(param_type) && !field_info[:pointer] ? "#{linkage_name}_input" : linkage_name
    params << IR::Param.new(name: param_binding.name, linkage_name: input_linkage_name, type: param_type, pointer: field_info[:pointer])
    frame_field_expr = async_frame_field_expression(frame_expr, field_info[:field_name], field_type)
    body << IR::Assignment.new(
      target: frame_field_expr,
      operator: "=",
      value: IR::Name.new(name: input_linkage_name, type: param_type, pointer: field_info[:pointer]),
    )
    # Retain proc-containing params: the frame outlives the constructor call stack,
    # so we must increment the env refcount so the caller releasing their copy is safe.
    if !field_info[:pointer] && contains_proc_storage_type?(param_type)
      body.concat(lower_proc_contained_retain_statements(frame_field_expr, param_type))
    end
  end

  body << IR::ExpressionStmt.new(
    expression: IR::Call.new(callee: resume_linkage_name, arguments: [raw_frame_expr], type: @ctx.types.fetch("void")),
  )
  body << IR::ReturnStmt.new(
    value: IR::AggregateLiteral.new(
      type: async_info[:task_type],
      fields: [
        IR::AggregateField.new(name: "frame", value: raw_frame_expr),
        IR::AggregateField.new(name: "ready", value: IR::Name.new(name: ready_linkage_name, type: async_info[:task_type].field("ready"), pointer: false)),
        IR::AggregateField.new(name: "set_waiter", value: IR::Name.new(name: set_waiter_linkage_name, type: async_info[:task_type].field("set_waiter"), pointer: false)),
        IR::AggregateField.new(name: "release", value: IR::Name.new(name: release_linkage_name, type: async_info[:task_type].field("release"), pointer: false)),
        IR::AggregateField.new(name: "take_result", value: IR::Name.new(name: take_result_linkage_name, type: async_info[:task_type].field("take_result"), pointer: false)),
        IR::AggregateField.new(name: "cancel", value: IR::Name.new(name: cancel_linkage_name, type: async_info[:task_type].field("cancel"), pointer: false)),
      ],
    ),
  )

  IR::Function.new(
    name: decl.name,
    linkage_name: constructor_linkage_name,
    params:,
    return_type: async_info[:task_type],
    body:,
    entry_point: false,
    method_receiver_param: !binding.type.receiver_type.nil?,
  )
end

#build_async_frame_type(frame_linkage_name, async_info) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/analysis.rb', line 217

def build_async_frame_type(frame_linkage_name, async_info)
  fields = {
    "ready" => @ctx.types.fetch("bool"),
    "cancelled" => @ctx.types.fetch("bool"),
    "waiter_frame" => async_info[:void_ptr],
    "waiter" => async_info[:wake_type],
  }
  fields["state"] = @ctx.types.fetch("int") unless async_info[:await_fields].empty?
  unless async_info[:result_type] == @ctx.types.fetch("void")
    fields["result"] = async_info[:result_type]
  end
  async_info[:param_fields].each_value do |field_info|
    fields[field_info[:field_name]] = field_info[:type]
  end
  async_info[:local_fields].each_value do |field_info|
    fields[field_info[:field_name]] = field_info[:storage_type]
  end
  async_info[:await_fields].each_value do |field_info|
    next if fields.key?(field_info[:field_name])

    fields[field_info[:field_name]] = field_info[:task_type]
  end

  Types::Struct.new(frame_linkage_name).define_fields(fields)
end

#build_async_main_entrypoint(binding, _constructor_c_name, async_info) ⇒ Object

Raises:



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# File 'lib/milk_tea/core/lowering/async.rb', line 5

def build_async_main_entrypoint(binding, _constructor_c_name, async_info)
  task_type = async_info[:task_type]
  signature = root_main_entrypoint_signature(binding)
  raise LoweringError.new("async main entrypoint requires a supported signature",
    line: 0, column: 0, path: @ctx.current_analysis_path) unless signature

  params, setup_statements, call_arguments, cleanup_statements = build_root_main_entrypoint_bridge(signature)
  body = []
  env = empty_env

  root_proc_name = "__mt_async_main_root"
  result_name = "__mt_result"

  body.concat(setup_statements)
  argument_names = binding.type.params.each_index.map { |index| "__mt_async_main_arg_#{index + 1}" }
  binding.type.params.each_with_index do |param, index|
    name = argument_names.fetch(index)
    env[:scopes].last[name] = local_binding(type: param.type, linkage_name: name, mutable: false, pointer: false)
    body << IR::LocalDecl.new(
      name: name,
      linkage_name: name,
      type: param.type,
      value: call_arguments.fetch(index),
    )
  end

  proc_expression = AST::ProcExpr.new(
    params: [],
    return_type: ast_type_ref_for(task_type),
    body: [
      AST::ReturnStmt.new(
        value: AST::Call.new(
          callee: AST::Identifier.new(name: binding.name),
          arguments: argument_names.map { |name| AST::Argument.new(name: nil, value: AST::Identifier.new(name: name)) },
        ),
      ),
    ],
  )
  root_proc_type = Types::Registry.proc(params: [], return_type: task_type)
  proc_setup, proc_value = lower_proc_expression_for_local(proc_expression, env:, local_name: root_proc_name, proc_type: root_proc_type)
  body.concat(proc_setup)
  body << IR::LocalDecl.new(
    name: root_proc_name,
    linkage_name: root_proc_name,
    type: root_proc_type,
    value: proc_value,
  )

  root_proc_expr = IR::Name.new(name: root_proc_name, type: root_proc_type, pointer: false)

  if async_info[:result_type] == @ctx.types.fetch("int")
    wait_callee = async_main_runtime_callee_name("wait", type_arguments: [async_info[:result_type]])
    body << IR::LocalDecl.new(
      name: result_name,
      linkage_name: result_name,
      type: @ctx.types.fetch("int"),
      value: IR::Call.new(
        callee: wait_callee,
        arguments: [root_proc_expr],
        type: @ctx.types.fetch("int"),
      ),
    )
  else
    run_callee = async_main_runtime_callee_name("run")
    body << IR::ExpressionStmt.new(
      expression: IR::Call.new(
        callee: run_callee,
        arguments: [root_proc_expr],
        type: @ctx.types.fetch("void"),
      ),
    )
  end

  body << IR::ExpressionStmt.new(
    expression: lower_proc_release_expression(root_proc_expr, root_proc_type),
  )
  body.concat(cleanup_statements)
  body << IR::ReturnStmt.new(
    value: async_info[:result_type] == @ctx.types.fetch("int") ? IR::Name.new(name: result_name, type: @ctx.types.fetch("int"), pointer: false) : IR::IntegerLiteral.new(value: 0, type: @ctx.types.fetch("int")),
  )

  IR::Function.new(
    name: binding.name,
    linkage_name: "main",
    params:,
    return_type: @ctx.types.fetch("int"),
    body: body,
    entry_point: true,
  )
end

#build_async_ready_function(frame_type, ready_linkage_name, async_info) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 368

def build_async_ready_function(frame_type, ready_linkage_name, async_info)
  frame_expr = IR::Name.new(name: async_frame_local_name, type: pointer_to(frame_type), pointer: false)

  IR::Function.new(
    name: "#{ready_linkage_name}_fn",
    linkage_name: ready_linkage_name,
    params: [IR::Param.new(name: "frame", linkage_name: async_frame_raw_name, type: async_info[:void_ptr], pointer: false)],
    return_type: @ctx.types.fetch("bool"),
    body: [
      async_frame_cast_declaration(frame_type, async_info),
      IR::ReturnStmt.new(value: async_frame_field_expression(frame_expr, "ready", @ctx.types.fetch("bool"))),
    ],
    entry_point: false,
  )
end

#build_async_release_function(frame_type, release_linkage_name, async_info) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 416

def build_async_release_function(frame_type, release_linkage_name, async_info)
  frame_expr = IR::Name.new(name: async_frame_local_name, type: pointer_to(frame_type), pointer: false)
  raw_frame_expr = IR::Name.new(name: async_frame_raw_name, type: async_info[:void_ptr], pointer: false)

  body = [async_frame_cast_declaration(frame_type, async_info)]

  not_ready_expr = IR::Unary.new(operator: "not", operand: async_frame_field_expression(frame_expr, "ready", @ctx.types.fetch("bool")), type: @ctx.types.fetch("bool"))
  not_ready_return = [IR::ReturnStmt.new(value: nil)]

  if async_info[:await_fields].any?
    await_release_stmts = []
    async_info[:await_fields].each_value do |field_info|
      task_field_expr = async_frame_field_expression(frame_expr, field_info[:field_name], field_info[:task_type])
      task_frame_expr = async_task_frame_expression(task_field_expr, field_info[:task_type])
      release_call = IR::ExpressionStmt.new(
        expression: async_task_call(task_field_expr, field_info[:task_type], "release", [task_frame_expr], @ctx.types.fetch("void")),
      )
      await_release_stmts << IR::IfStmt.new(
        condition: task_frame_expr,
        then_body: [release_call],
        else_body: nil,
      )
    end
    body << IR::IfStmt.new(
      condition: not_ready_expr,
      then_body: await_release_stmts + not_ready_return,
      else_body: nil,
    )
  else
    body << IR::IfStmt.new(
      condition: not_ready_expr,
      then_body: not_ready_return,
      else_body: nil,
    )
  end

  # Release proc-containing params (always initialized by constructor, but null-guard is safe).
  async_info[:param_fields].each_value do |field_info|
    next if field_info[:pointer]
    next unless contains_proc_storage_type?(field_info[:type])

    field_expr = async_frame_field_expression(frame_expr, field_info[:field_name], field_info[:type])
    body.concat(lower_async_frame_proc_release_statements(field_expr, field_info[:type]))
  end

  # Release proc-containing locals (may not be initialized if function returned early via branch,
  # so always null-guard via invoke pointer check on each proc).
  async_info[:local_fields].each_value do |field_info|
    next unless contains_proc_storage_type?(field_info[:storage_type])

    field_expr = async_frame_field_expression(frame_expr, field_info[:field_name], field_info[:storage_type])
    body.concat(lower_async_frame_proc_release_statements(field_expr, field_info[:storage_type]))
  end

  (async_info[:format_str_fields] || {}).each_key do |field_name|
    field_expr = async_frame_field_expression(frame_expr, field_name, @ctx.types.fetch("str"))
    body << IR::ExpressionStmt.new(
      expression: IR::Call.new(
        callee: "mt_format_str_release",
        arguments: [field_expr],
        type: @ctx.types.fetch("void"),
      ),
    )
  end

  async_info[:param_fields].each_value do |field_info|
    next unless field_info[:pointer]

    param_expr = async_frame_field_expression(frame_expr, field_info[:field_name], field_info[:type])
    body << IR::ExpressionStmt.new(
      expression: IR::Call.new(callee: "mt_async_free", arguments: [param_expr], type: @ctx.types.fetch("void")),
    )
  end

  body << IR::ExpressionStmt.new(expression: IR::Call.new(callee: "mt_async_free", arguments: [raw_frame_expr], type: @ctx.types.fetch("void")))
  body << IR::ReturnStmt.new(value: nil)

  IR::Function.new(
    name: "#{release_linkage_name}_fn",
    linkage_name: release_linkage_name,
    params: [IR::Param.new(name: "frame", linkage_name: async_frame_raw_name, type: async_info[:void_ptr], pointer: false)],
    return_type: @ctx.types.fetch("void"),
    body:,
    entry_point: false,
  )
end

#build_async_resume_function(binding, statements, frame_type, resume_linkage_name, async_info) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 332

def build_async_resume_function(binding, statements, frame_type, resume_linkage_name, async_info)
  async_info = async_info.merge(resume_linkage_name:)
  frame_expr = IR::Name.new(name: async_frame_local_name, type: pointer_to(frame_type), pointer: false)
  raw_frame_expr = IR::Name.new(name: async_frame_raw_name, type: async_info[:void_ptr], pointer: false)
  body = [async_frame_cast_declaration(frame_type, async_info)]

  env = async_resume_env_for(async_info)
  if async_info[:await_fields].empty?
    body.concat(lower_async_non_await_statements(statements, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers: []))
  else
    cases = (0..async_info[:await_fields].length).map do |state|
      IR::SwitchCase.new(
        value: IR::IntegerLiteral.new(value: state, type: @ctx.types.fetch("int")),
        body: [IR::GotoStmt.new(label: async_state_label(resume_linkage_name, state))],
      )
    end
    body << IR::SwitchStmt.new(expression: async_frame_field_expression(frame_expr, "state", @ctx.types.fetch("int")), cases:)
    body << IR::ReturnStmt.new(value: nil)
    body << IR::LabelStmt.new(name: async_state_label(resume_linkage_name, 0))
    body.concat(lower_async_cf_statements(statements, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers: []))
  end

  if async_info[:result_type] == @ctx.types.fetch("void") && !cfg_block_always_terminates?(statements)
    body.concat(async_complete_statements(frame_expr:, raw_frame_expr:, async_info:, value: nil, result_already_stored: true))
  end

  IR::Function.new(
    name: "#{binding.name}__resume",
    linkage_name: resume_linkage_name,
    params: [IR::Param.new(name: "frame", linkage_name: async_frame_raw_name, type: async_info[:void_ptr], pointer: false)],
    return_type: @ctx.types.fetch("void"),
    body:,
    entry_point: false,
  )
end

#build_async_set_waiter_function(frame_type, set_waiter_linkage_name, async_info) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 384

def build_async_set_waiter_function(frame_type, set_waiter_linkage_name, async_info)
  frame_expr = IR::Name.new(name: async_frame_local_name, type: pointer_to(frame_type), pointer: false)
  waiter_frame_expr = IR::Name.new(name: "waiter_frame", type: async_info[:void_ptr], pointer: false)
  waiter_expr = IR::Name.new(name: "waiter", type: async_info[:wake_type], pointer: false)

  IR::Function.new(
    name: "#{set_waiter_linkage_name}_fn",
    linkage_name: set_waiter_linkage_name,
    params: [
      IR::Param.new(name: "frame", linkage_name: async_frame_raw_name, type: async_info[:void_ptr], pointer: false),
      IR::Param.new(name: "waiter_frame", linkage_name: "waiter_frame", type: async_info[:void_ptr], pointer: false),
      IR::Param.new(name: "waiter", linkage_name: "waiter", type: async_info[:wake_type], pointer: false),
    ],
    return_type: @ctx.types.fetch("void"),
    body: [
      async_frame_cast_declaration(frame_type, async_info),
      IR::IfStmt.new(
        condition: async_frame_field_expression(frame_expr, "ready", @ctx.types.fetch("bool")),
        then_body: [
          IR::ExpressionStmt.new(expression: IR::Call.new(callee: waiter_expr, arguments: [waiter_frame_expr], type: @ctx.types.fetch("void"))),
          IR::ReturnStmt.new(value: nil),
        ],
        else_body: nil,
      ),
      IR::Assignment.new(target: async_frame_field_expression(frame_expr, "waiter_frame", async_info[:void_ptr]), operator: "=", value: waiter_frame_expr),
      IR::Assignment.new(target: async_frame_field_expression(frame_expr, "waiter", async_info[:wake_type]), operator: "=", value: waiter_expr),
      IR::ReturnStmt.new(value: nil),
    ],
    entry_point: false,
  )
end

#build_async_take_result_function(frame_type, take_result_linkage_name, async_info) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 626

def build_async_take_result_function(frame_type, take_result_linkage_name, async_info)
  frame_expr = IR::Name.new(name: async_frame_local_name, type: pointer_to(frame_type), pointer: false)
  body = if async_info[:result_type] == @ctx.types.fetch("void")
            [IR::ReturnStmt.new(value: nil)]
          else
            [async_frame_cast_declaration(frame_type, async_info),
            IR::ReturnStmt.new(value: async_frame_field_expression(frame_expr, "result", async_info[:result_type]))]
          end

  IR::Function.new(
    name: "#{take_result_linkage_name}_fn",
    linkage_name: take_result_linkage_name,
    params: [IR::Param.new(name: "frame", linkage_name: async_frame_raw_name, type: async_info[:void_ptr], pointer: false)],
    return_type: async_info[:result_type],
    body:,
    entry_point: false,
  )
end

#build_async_while_with_condition_setup(condition_setup, condition, body, break_label) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 212

def build_async_while_with_condition_setup(condition_setup, condition, body, break_label)
  if condition_setup.empty?
    stmts = [IR::WhileStmt.new(condition:, body:)]
    stmts << IR::LabelStmt.new(name: break_label) if contains_label_target?(body, break_label)
    return stmts
  end

  loop_body = [
    *condition_setup,
    IR::IfStmt.new(
      condition: IR::Unary.new(operator: "not", operand: condition, type: @ctx.types.fetch("bool")),
      then_body: [loop_exit_statement(loop_exit_break(break_label), local_defers: [], outer_defers: [])],
      else_body: nil,
    ),
    *body,
  ]
  stmts = [IR::WhileStmt.new(condition: IR::BooleanLiteral.new(value: true, type: @ctx.types.fetch("bool")), body: loop_body)]
  stmts << IR::LabelStmt.new(name: break_label) if contains_label_target?(loop_body, break_label)
  stmts
end

#build_root_main_entrypoint(binding) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 102

def build_root_main_entrypoint(binding)
  return nil if binding.async

  signature = root_main_entrypoint_signature(binding)
  return nil unless signature

  params, setup_statements, call_arguments, cleanup_statements = build_root_main_entrypoint_bridge(signature)
  return_type = binding.body_return_type
  body = []
  call = IR::Call.new(
    callee: function_binding_c_name(binding, module_name: @ctx.module_name),
    arguments: call_arguments,
    type: return_type,
  )

  body.concat(setup_statements)
  if return_type == @ctx.types.fetch("void")
    body << IR::ExpressionStmt.new(expression: call)
    body.concat(cleanup_statements)
    body << IR::ReturnStmt.new(value: IR::IntegerLiteral.new(value: 0, type: @ctx.types.fetch("int")))
  elsif cleanup_statements.empty?
    body << IR::ReturnStmt.new(value: call)
  else
    result_name = "__mt_result"
    body << IR::LocalDecl.new(
      name: result_name,
      linkage_name: result_name,
      type: @ctx.types.fetch("int"),
      value: call,
    )
    body.concat(cleanup_statements)
    body << IR::ReturnStmt.new(value: IR::Name.new(name: result_name, type: @ctx.types.fetch("int"), pointer: false))
  end

  IR::Function.new(
    name: binding.name,
    linkage_name: "main",
    params:,
    return_type: @ctx.types.fetch("int"),
    body:,
    entry_point: true,
  )
end

#build_root_main_entrypoint_bridge(signature) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 146

def build_root_main_entrypoint_bridge(signature)
  argc_type = @ctx.types.fetch("int")
  raw_argv_type = pointer_to(pointer_to(@ctx.types.fetch("char")))
  argc_name = "argc"
  argv_name = "argv"

  case signature[:kind]
  when :none
    [[], [], [], []]
  when :raw_char_ptr_ptr
    argc_expr = IR::Name.new(name: argc_name, type: argc_type, pointer: false)
    argv_expr = IR::Name.new(name: argv_name, type: raw_argv_type, pointer: false)
    [
      [
        IR::Param.new(name: argc_name, linkage_name: argc_name, type: argc_type, pointer: false),
        IR::Param.new(name: argv_name, linkage_name: argv_name, type: raw_argv_type, pointer: false),
      ],
      [],
      [argc_expr, argv_expr],
      [],
    ]
  when :raw_cstr_ptr
    argc_expr = IR::Name.new(name: argc_name, type: argc_type, pointer: false)
    argv_expr = IR::Cast.new(
      target_type: signature[:argv_type],
      expression: IR::Name.new(name: argv_name, type: raw_argv_type, pointer: false),
      type: signature[:argv_type],
    )
    [
      [
        IR::Param.new(name: argc_name, linkage_name: argc_name, type: argc_type, pointer: false),
        IR::Param.new(name: argv_name, linkage_name: argv_name, type: raw_argv_type, pointer: false),
      ],
      [],
      [argc_expr, argv_expr],
      [],
    ]
  when :span_str
    items_type = pointer_to(@ctx.types.fetch("str"))
    items_name = "__mt_args_items"
    args_name = "__mt_args"
    items_expr = IR::Name.new(name: items_name, type: items_type, pointer: false)
    args_expr = IR::Name.new(name: args_name, type: signature[:args_type], pointer: false)
    argc_expr = IR::Name.new(name: argc_name, type: argc_type, pointer: false)
    argv_expr = IR::Name.new(name: argv_name, type: raw_argv_type, pointer: false)

    setup = [
      IR::LocalDecl.new(
        name: items_name,
        linkage_name: items_name,
        type: items_type,
        value: IR::NullLiteral.new(type: items_type),
      ),
      IR::LocalDecl.new(
        name: args_name,
        linkage_name: args_name,
        type: signature[:args_type],
        value: IR::Call.new(
          callee: "mt_entry_argv_to_span_str",
          arguments: [
            argc_expr,
            argv_expr,
            IR::AddressOf.new(expression: items_expr, type: pointer_to(items_type)),
          ],
          type: signature[:args_type],
        ),
      ),
    ]
    cleanup = [
      IR::ExpressionStmt.new(
        expression: IR::Call.new(callee: "mt_free_entry_argv_strs", arguments: [items_expr], type: @ctx.types.fetch("void")),
      ),
    ]

    [
      [
        IR::Param.new(name: argc_name, linkage_name: argc_name, type: argc_type, pointer: false),
        IR::Param.new(name: argv_name, linkage_name: argv_name, type: raw_argv_type, pointer: false),
      ],
      setup,
      [args_expr],
      cleanup,
    ]
  else
    raise LoweringError.new("unsupported root main entrypoint bridge #{signature[:kind]}",
      line: 0, column: 0, path: @ctx.current_analysis_path)
  end
end

#fresh_async_temp_name(counter) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/normalization.rb', line 452

def fresh_async_temp_name(counter)
  counter[:value] += 1
  "__mt_async_tmp_#{counter[:value]}"
end

#lower_async_assignment_statement(statement, env:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 981

def lower_async_assignment_statement(statement, env:)
  lowered = []
  target = lower_assignment_target(statement.target, env:)
  prepared_setup, prepared_value = prepare_expression_for_inline_lowering(
    statement.value,
    env:,
    expected_type: target.type,
    allow_root_statement_foreign: true,
  )
  lowered.concat(prepared_setup)

  if (foreign_call = foreign_call_info(prepared_value, env))
    setup, value, call_type, release_assignments, cleanup_statements = lower_foreign_call_components(
      foreign_call,
      env:,
      expected_type: target.type,
      statement_position: false,
    )
    lowered.concat(setup)
    raise LoweringError.new("foreign call used in assignment must return a value", line: 0, column: 0, path: @ctx.current_analysis_path) if call_type == @ctx.types.fetch("void")
    raise LoweringError.new("consuming foreign calls must return void", line: 0, column: 0, path: @ctx.current_analysis_path) unless release_assignments.empty?

    lowered << IR::Assignment.new(target:, operator: statement.operator, value:)
    lowered.concat(cleanup_statements)
    update_cstr_metadata_for_assignment!(statement, prepared_value, env)
    return lowered
  end

  value = if statement.operator == "="
            lower_contextual_expression(
              prepared_value,
              env:,
              expected_type: target.type,
              external_numeric: external_numeric_assignment_target?(statement.target, env:),
              contextual_int_to_float: contextual_int_to_float_target?(target.type),
            )
          elsif ["+=", "-=", "*=", "/="].include?(statement.operator)
            lower_contextual_expression(
              prepared_value,
              env:,
              expected_type: target.type,
              contextual_int_to_float: contextual_int_to_float_target?(target.type),
            )
          else
            lower_expression(prepared_value, env:, expected_type: target.type)
          end
  update_cstr_metadata_for_assignment!(statement, prepared_value, env)
  operator = statement.operator
  if ["+=", "-=", "*=", "/="].include?(operator) &&
      (target.type.is_a?(Types::Vector) || target.type.is_a?(Types::Matrix) || target.type.is_a?(Types::Quaternion))
    binary_op = operator[0...-1]
    expanded = lower_vector_binary_op(binary_op, target, target.type, value, value.type, target.type)
    value = expanded || IR::Binary.new(operator: binary_op, left: target, right: value, type: target.type)
    operator = "="
  end
  if operator == "=" && contains_proc_storage_type?(target.type)
    rhs_name = fresh_c_temp_name(env, "proc_assign")
    lowered << IR::LocalDecl.new(name: rhs_name, linkage_name: rhs_name, type: target.type, value:)
    rhs = IR::Name.new(name: rhs_name, type: target.type, pointer: false)
    lowered.concat(lower_proc_selective_retain_statements(rhs, statement.value, target.type))
    lowered.concat(lower_proc_contained_guarded_release_statements(target, target.type))
    lowered << IR::Assignment.new(target:, operator: "=", value: rhs)
  else
    lowered << IR::Assignment.new(target:, operator:, value:)
  end
  lowered
end

#lower_async_await_statement(statement, await_info:, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, field_info: nil, cleanup: [], active_defers: [], loop_flow: nil) ⇒ Object

Raises:



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1123

def lower_async_await_statement(statement, await_info:, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, field_info: nil, cleanup: [], active_defers: [], loop_flow: nil)
  lowered = []
  await_expression = case statement
                      when AST::LocalDecl then statement.value
                      when AST::Assignment then statement.value
                      when AST::ExpressionStmt then statement.expression
                      when AST::ReturnStmt then statement.value
                      end
  prepared_setup, prepared_task = prepare_expression_for_inline_lowering(
    await_expression.expression,
    env:,
    expected_type: await_info[:task_type],
  )
  lowered.concat(prepared_setup)
  raise LoweringError.new("await does not support foreign task expressions", line: 0, column: 0, path: @ctx.current_analysis_path) if foreign_call_info(prepared_task, env)

  task_expr = async_frame_field_expression(frame_expr, await_info[:field_name], await_info[:task_type])
  task_frame_expr = async_task_frame_expression(task_expr, await_info[:task_type])
  ready_call = async_task_call(task_expr, await_info[:task_type], "ready", [task_frame_expr], @ctx.types.fetch("bool"))
  set_waiter_call = async_task_call(
    task_expr,
    await_info[:task_type],
    "set_waiter",
    [
      task_frame_expr,
      raw_frame_expr,
      IR::Name.new(name: resume_linkage_name, type: async_info[:wake_type], pointer: false),
    ],
    @ctx.types.fetch("void"),
  )
  take_result_call = async_task_call(task_expr, await_info[:task_type], "take_result", [task_frame_expr], await_info[:result_type])
  release_call = async_task_call(task_expr, await_info[:task_type], "release", [task_frame_expr], @ctx.types.fetch("void"))

  unless await_info[:reuse_existing_storage]
    lowered << IR::Assignment.new(
      target: task_expr,
      operator: "=",
      value: lower_contextual_expression(prepared_task, env:, expected_type: await_info[:task_type]),
    )
  end
  lowered << IR::IfStmt.new(
    condition: IR::Unary.new(operator: "not", operand: ready_call, type: @ctx.types.fetch("bool")),
    then_body: [
      IR::Assignment.new(
        target: async_frame_field_expression(frame_expr, "state", @ctx.types.fetch("int")),
        operator: "=",
        value: IR::IntegerLiteral.new(value: await_info[:state], type: @ctx.types.fetch("int")),
      ),
      IR::ExpressionStmt.new(expression: set_waiter_call),
      IR::ReturnStmt.new(value: nil),
    ],
    else_body: nil,
  )
  lowered << IR::LabelStmt.new(name: async_state_label(resume_linkage_name, await_info[:state]))

  case statement
  when AST::LocalDecl
    storage_type = field_info[:storage_type]
    target = async_frame_field_expression(frame_expr, field_info[:field_name], storage_type)
    lowered << IR::Assignment.new(target:, operator: "=", value: take_result_call)
    lowered << IR::ExpressionStmt.new(expression: release_call)
    if statement.else_body
      else_env = duplicate_env(env)
      if statement.else_binding
        current_actual_scope(else_env[:scopes])[statement.else_binding.name] = local_binding(
          type: let_else_error_type(storage_type),
          storage_type:,
          linkage_name: async_frame_field_c_name(field_info[:field_name]),
          mutable: false,
          pointer: false,
          projection: :result_failure_error,
        )
      end
      else_body = lower_async_body(
        statement.else_body,
        env: else_env,
        frame_expr:,
        raw_frame_expr:,
        resume_linkage_name:,
        async_info:,
        active_defers:,
        loop_flow:,
      )
      lowered << IR::IfStmt.new(
        condition: let_else_failure_condition(target, storage_type),
        then_body: else_body,
        else_body: nil,
      )
    end
  when AST::Assignment
    lowered << IR::Assignment.new(target: lower_assignment_target(statement.target, env:), operator: statement.operator, value: take_result_call)
    lowered << IR::ExpressionStmt.new(expression: release_call)
  when AST::ExpressionStmt
    lowered << IR::ExpressionStmt.new(expression: take_result_call)
    lowered << IR::ExpressionStmt.new(expression: release_call)
  when AST::ReturnStmt
    if await_info[:result_type] == @ctx.types.fetch("void")
      lowered << IR::ExpressionStmt.new(expression: take_result_call)
      lowered << IR::ExpressionStmt.new(expression: release_call)
      lowered.concat(cleanup)
      lowered.concat(async_complete_statements(frame_expr:, raw_frame_expr:, async_info:, value: nil, result_already_stored: true))
    else
      lowered << IR::Assignment.new(
        target: async_frame_field_expression(frame_expr, "result", async_info[:result_type]),
        operator: "=",
        value: take_result_call,
      )
      lowered << IR::ExpressionStmt.new(expression: release_call)
      lowered.concat(cleanup)
      lowered.concat(async_complete_statements(frame_expr:, raw_frame_expr:, async_info:, value: nil, result_already_stored: true))
    end
  end

  lowered
end

#lower_async_body(body, env:, frame_expr:, raw_frame_expr:, async_info:, resume_linkage_name: nil, active_defers: [], loop_flow: nil) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 204

def lower_async_body(body, env:, frame_expr:, raw_frame_expr:, async_info:, resume_linkage_name: nil, active_defers: [], loop_flow: nil)
  if statements_contain_await?(body, async_info)
    lower_async_cf_statements(body, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow:)
  else
    lower_async_non_await_statements(body, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers:, loop_flow:)
  end
end

#lower_async_cf_collection_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:) ⇒ Object

Raises:



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 411

def lower_async_cf_collection_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:)
  iterable_type = infer_expression_type(statement.iterable, env:)
  element_type = collection_loop_type(iterable_type)
  raise LoweringError.new("for loop expects start..stop, array[T, N], or span[T], got #{iterable_type}", line: 0, column: 0, path: @ctx.current_analysis_path) unless element_type

  iterable_setup, prepared_iterable = prepare_expression_for_inline_lowering(statement.iterable, env:, expected_type: iterable_type)
  continue_label = fresh_c_temp_name(env, "loop_continue")
  break_label = fresh_c_temp_name(env, "loop_break")
  iterable_field = async_info[:local_fields].fetch(async_collection_iterable_field_key(statement))
  index_field = async_info[:local_fields].fetch(async_collection_index_field_key(statement))
  iterable_ref = async_frame_field_expression(frame_expr, iterable_field[:field_name], iterable_type)
  index_ref = async_frame_field_expression(frame_expr, index_field[:field_name], @ctx.types.fetch("ptr_uint"))

  # Loop variable stored in frame so it survives suspension
  loop_var_field = async_info[:local_fields].fetch(statement.name)
  loop_var_expr = async_frame_field_expression(frame_expr, loop_var_field[:field_name], element_type)

  item_value = if array_type?(iterable_type)
                  IR::Index.new(receiver: iterable_ref, index: index_ref, type: element_type)
                else
                  data_ref = IR::Member.new(receiver: iterable_ref, member: "data", type: pointer_to(element_type))
                  IR::Index.new(receiver: data_ref, index: index_ref, type: element_type)
                end
  stop_value = if array_type?(iterable_type)
                  IR::IntegerLiteral.new(value: array_length(iterable_type), type: @ctx.types.fetch("ptr_uint"))
                else
                  IR::Member.new(receiver: iterable_ref, member: "len", type: @ctx.types.fetch("ptr_uint"))
                end

  inner_env = duplicate_env(env)
  inner_env[:scopes].last[statement.name] = local_binding(
    type: element_type, linkage_name: async_frame_field_c_name(loop_var_field[:field_name]), mutable: true, pointer: false
  )
  inner_loop_flow = loop_flow(break_target: loop_exit_break(break_label), continue_target: loop_exit_continue(continue_label))

  assign_item = IR::Assignment.new(target: loop_var_expr, operator: "=", value: item_value)
  body_stmts = lower_async_body(statement.body, env: inner_env, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow: inner_loop_flow)
  body_stmts << IR::LabelStmt.new(name: continue_label) if contains_label_target?(body_stmts, continue_label)

  stmts = [
    *iterable_setup,
    IR::Assignment.new(target: iterable_ref, operator: "=", value: lower_expression(prepared_iterable, env:, expected_type: iterable_type)),
    IR::Assignment.new(target: index_ref, operator: "=", value: IR::IntegerLiteral.new(value: 0, type: @ctx.types.fetch("ptr_uint"))),
    IR::WhileStmt.new(
      condition: IR::Binary.new(operator: "<", left: index_ref, right: stop_value, type: @ctx.types.fetch("bool")),
      body: [assign_item] + body_stmts + [
        IR::Assignment.new(target: index_ref, operator: "+=", value: IR::IntegerLiteral.new(value: 1, type: @ctx.types.fetch("ptr_uint"))),
      ],
    ),
  ]
  stmts << IR::LabelStmt.new(name: break_label) if contains_label_target?(body_stmts, break_label)
  stmts
end

#lower_async_cf_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 353

def lower_async_cf_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:)
  return lower_async_cf_parallel_collection_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:) if statement.parallel?

  if range_iterable?(statement.iterable)
    lower_async_cf_range_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:)
  else
    lower_async_cf_collection_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:)
  end
end

#lower_async_cf_if_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 319

def lower_async_cf_if_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow:)
  branch_entries = statement.branches.map do |branch|
    condition_setup, prepared_cond = prepare_expression_for_inline_lowering(branch.condition, env:)
    condition = lower_contextual_expression(prepared_cond, env:, expected_type: @ctx.types.fetch("bool"))
    body = lower_async_body(branch.body, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow:)
    { condition_setup:, condition:, body: }
  end

  else_body = if statement.else_body
    lower_async_body(statement.else_body, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow:)
  end

  nested_else = else_body
  branch_entries.reverse_each do |entry|
    nested_else = [
      *entry[:condition_setup],
      IR::IfStmt.new(condition: entry[:condition], then_body: entry[:body], else_body: nested_else),
    ]
  end
  nested_else || []
end

#lower_async_cf_match_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 553

def lower_async_cf_match_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow:)
  expr_setup, prepared_expr = prepare_expression_for_inline_lowering(statement.expression, env:)
  match_expr = lower_contextual_expression(prepared_expr, env:, expected_type: nil)
  match_type = infer_expression_type(statement.expression, env:)
  arm_loop_flow = switch_loop_flow(loop_flow, [])

  if match_type.is_a?(Types::Variant)
    if statement.arms.any? { |arm| arm.binding_name && !wildcard_arm_pattern?(arm.pattern) } &&
        !duplicable_foreign_argument_expression?(match_expr)
      scrutinee_linkage_name = fresh_c_temp_name(env, "match_value")
      expr_setup << IR::LocalDecl.new(name: scrutinee_linkage_name, linkage_name: scrutinee_linkage_name, type: match_type, value: match_expr)
      match_expr = IR::Name.new(name: scrutinee_linkage_name, type: match_type, pointer: false)
    end

    kind_type = @ctx.types.fetch("int")
    kind_expr = IR::Member.new(receiver: match_expr, member: "kind", type: kind_type)
    cases = statement.arms.map do |arm|
      arm_env, binding_decl = async_variant_match_arm_binding(arm, match_expr, match_type, env:, frame_expr:, local_fields: async_info[:local_fields])
      arm_body = lower_async_body(arm.body, env: arm_env, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow: arm_loop_flow)
      body = [binding_decl, *arm_body].compact + [IR::BreakStmt.new]
      if wildcard_arm_pattern?(arm.pattern)
        IR::SwitchDefaultCase.new(body: body)
      else
        arm_name = variant_match_arm_name_from_pattern(arm.pattern)
        IR::SwitchCase.new(value: IR::Name.new(name: enum_member_c_name(match_type, "kind_#{arm_name}"), type: kind_type, pointer: false), body: body)
      end
    end

    return expr_setup + [IR::SwitchStmt.new(expression: kind_expr, cases:, exhaustive: true)]
  end

  cases = statement.arms.map do |arm|
    arm_body = lower_async_body(arm.body, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow: arm_loop_flow)
    if wildcard_arm_pattern?(arm.pattern)
      IR::SwitchDefaultCase.new(body: arm_body + [IR::BreakStmt.new])
    else
      IR::SwitchCase.new(value: lower_expression(arm.pattern, env:, expected_type: match_type), body: arm_body + [IR::BreakStmt.new])
    end
  end

  expr_setup + [IR::SwitchStmt.new(expression: match_expr, cases:, exhaustive: true)]
end

#lower_async_cf_parallel_collection_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 465

def lower_async_cf_parallel_collection_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:)
  infos = statement.bindings.each_with_index.map do |binding, index|
    iterable = statement.iterables[index]
    iterable_type = infer_expression_type(iterable, env:)
    element_type = collection_loop_type(iterable_type)
    raise LoweringError.new("parallel for loops expect arrays or spans for each iterable, got #{iterable_type}", line: 0, column: 0, path: @ctx.current_analysis_path) unless element_type

    {
      binding:,
      iterable:,
      iterable_type:,
      element_type:,
      binding_type: collection_loop_binding_type(iterable_type, element_type) || element_type,
      iterable_field: async_info[:local_fields].fetch(async_collection_iterable_field_key(statement, index)),
    }
  end

  iterable_entries = infos.map do |info|
    setup, prepared_iterable = prepare_expression_for_inline_lowering(info[:iterable], env:, expected_type: info[:iterable_type])
    info.merge(setup:, prepared_iterable:)
  end

  continue_label = fresh_c_temp_name(env, "loop_continue")
  break_label = fresh_c_temp_name(env, "loop_break")
  index_field = async_info[:local_fields].fetch(async_collection_index_field_key(statement))
  index_ref = async_frame_field_expression(frame_expr, index_field[:field_name], @ctx.types.fetch("ptr_uint"))
  iterable_refs = iterable_entries.map do |entry|
    async_frame_field_expression(frame_expr, entry[:iterable_field][:field_name], entry[:iterable_type])
  end
  stop_value = collection_loop_stop_value(iterable_refs.first, iterable_entries.first[:iterable_type])

  inner_env = duplicate_env(env)
  assign_items = iterable_entries.map.with_index do |entry, index|
    item_value = collection_loop_item_value(iterable_refs[index], entry[:iterable_type], index_ref, entry[:element_type])
    loop_item_value = if ref_type?(entry[:binding_type])
                        IR::AddressOf.new(expression: item_value, type: entry[:binding_type])
                      else
                        item_value
                      end
    binding_field = async_info[:local_fields].fetch(entry[:binding].name)
    binding_target = async_frame_field_expression(frame_expr, binding_field[:field_name], entry[:binding_type])
    inner_env[:scopes].last[entry[:binding].name] = local_binding(
      type: entry[:binding_type],
      linkage_name: async_frame_field_c_name(binding_field[:field_name]),
      mutable: true,
      pointer: false,
    )
    IR::Assignment.new(target: binding_target, operator: "=", value: loop_item_value)
  end
  inner_loop_flow = loop_flow(break_target: loop_exit_break(break_label), continue_target: loop_exit_continue(continue_label))
  body_stmts = lower_async_body(statement.body, env: inner_env, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow: inner_loop_flow)
  body_stmts << IR::LabelStmt.new(name: continue_label) if contains_label_target?(body_stmts, continue_label)

  length_checks = iterable_entries.drop(1).each_with_index.map do |entry, offset|
    IR::IfStmt.new(
      condition: IR::Binary.new(
        operator: "!=",
        left: collection_loop_stop_value(iterable_refs[offset + 1], entry[:iterable_type]),
        right: stop_value,
        type: @ctx.types.fetch("bool"),
      ),
      then_body: [lower_fatal_statement("parallel for iterables must have matching lengths", env:)],
      else_body: nil,
    )
  end

  stmts = [
    *iterable_entries.flat_map { |entry| entry[:setup] },
    *iterable_entries.each_with_index.map do |entry, index|
      IR::Assignment.new(
        target: iterable_refs[index],
        operator: "=",
        value: lower_expression(entry[:prepared_iterable], env:, expected_type: entry[:iterable_type]),
      )
    end,
    *length_checks,
    IR::Assignment.new(target: index_ref, operator: "=", value: IR::IntegerLiteral.new(value: 0, type: @ctx.types.fetch("ptr_uint"))),
    IR::WhileStmt.new(
      condition: IR::Binary.new(operator: "<", left: index_ref, right: stop_value, type: @ctx.types.fetch("bool")),
      body: assign_items + body_stmts + [
        IR::Assignment.new(target: index_ref, operator: "+=", value: IR::IntegerLiteral.new(value: 1, type: @ctx.types.fetch("ptr_uint"))),
      ],
    ),
  ]
  stmts << IR::LabelStmt.new(name: break_label) if contains_label_target?(body_stmts, break_label)
  stmts
end

#lower_async_cf_range_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 372

def lower_async_cf_range_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:)
  loop_var_name = statement.name
  loop_var_type = infer_range_loop_type(statement.iterable, env:)
  loop_var_field = async_info[:local_fields].fetch(loop_var_name)
  loop_var_expr = async_frame_field_expression(frame_expr, loop_var_field[:field_name], loop_var_type)
  continue_label = fresh_c_temp_name(env, "loop_continue")
  break_label = fresh_c_temp_name(env, "loop_break")

  start_expr, stop_expr, inclusive = lower_range_call(statement.iterable, env:)

  # Store stop value in frame too so it survives suspension
  stop_field_name = "#{loop_var_field[:field_name]}_stop"
  async_info[:local_fields][stop_field_name] ||= { field_name: stop_field_name, type: loop_var_type, mutable: true }
  stop_field_expr = async_frame_field_expression(frame_expr, stop_field_name, loop_var_type)

  inner_env = duplicate_env(env)
  inner_env[:scopes].last[loop_var_name] = local_binding(
    type: loop_var_type,
    linkage_name: async_frame_field_c_name(loop_var_field[:field_name]),
    mutable: true, pointer: false
  )
  inner_loop_flow = loop_flow(break_target: loop_exit_break(break_label), continue_target: loop_exit_continue(continue_label))

  body = lower_async_body(statement.body, env: inner_env, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow: inner_loop_flow)
  body << IR::LabelStmt.new(name: continue_label) if contains_label_target?(body, continue_label)

  cmp_op = inclusive ? "<=" : "<"
  stmts = [
    IR::Assignment.new(target: loop_var_expr, operator: "=", value: start_expr),
    IR::Assignment.new(target: stop_field_expr, operator: "=", value: stop_expr),
    IR::WhileStmt.new(
      condition: IR::Binary.new(operator: cmp_op, left: loop_var_expr, right: stop_field_expr, type: @ctx.types.fetch("bool")),
      body: body + [IR::Assignment.new(target: loop_var_expr, operator: "+=", value: IR::IntegerLiteral.new(value: 1, type: loop_var_type))],
    ),
  ]
  stmts << IR::LabelStmt.new(name: break_label) if contains_label_target?(body, break_label)
  stmts
end

#lower_async_cf_statements(statements, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers: [], loop_flow: nil) ⇒ Object

Lower a list of statements that MAY contain await expressions inside nested control flow. CPS-via-goto: labels placed inside if/while/match bodies, reachable from top-level switch dispatch.



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 235

def lower_async_cf_statements(statements, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers: [], loop_flow: nil)
  lowered = []
  local_defers = []
  env[:return_context] = async_return_context(
    return_type: async_info[:result_type],
    active_defers:,
    local_defers:,
    frame_expr:,
    raw_frame_expr:,
    async_info:,
  )

  statements.each do |statement|
    case statement
    when AST::LocalDecl
      field_info = async_info[:local_fields].fetch(async_local_decl_field_key(statement))
      await_info = async_info[:await_fields][statement.value&.object_id]
      if await_info
        lowered.concat(lower_async_await_statement(statement, field_info:, await_info:, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers: active_defers + local_defers, loop_flow: nested_loop_flow(loop_flow, local_defers)))
      else
        lowered.concat(lower_async_local_decl_statement(statement, field_info:, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers: active_defers + local_defers, loop_flow: nested_loop_flow(loop_flow, local_defers)))
      end
      async_bind_local!(env, statement.name, field_info) if bind_let_else_local?(statement)
    when AST::Assignment
      await_info = async_info[:await_fields][statement.value&.object_id]
      if await_info
        lowered.concat(lower_async_await_statement(statement, await_info:, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:))
      else
        lowered.concat(lower_async_assignment_statement(statement, env:))
      end
    when AST::ExpressionStmt
      await_info = async_info[:await_fields][statement.expression&.object_id]
      if await_info
        lowered.concat(lower_async_await_statement(statement, await_info:, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:))
      else
        lowered.concat(lower_async_expression_statement(statement, env:))
      end
    when AST::ReturnStmt
      cleanup = lower_async_cleanup_entries(local_defers, active_defers, frame_expr:, raw_frame_expr:, async_info:)
      await_info = async_info[:await_fields][statement.value&.object_id]
      if await_info
        lowered.concat(lower_async_await_statement(statement, await_info:, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, cleanup:))
      else
        lowered.concat(lower_async_return_statement(statement, env:, frame_expr:, raw_frame_expr:, async_info:, cleanup:))
      end
    when AST::IfStmt
      lowered.concat(lower_async_cf_if_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers: active_defers + local_defers, loop_flow: nested_loop_flow(loop_flow, local_defers)))
    when AST::WhileStmt
      lowered.concat(lower_async_cf_while_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers: active_defers + local_defers, loop_flow: nested_loop_flow(loop_flow, local_defers)))
    when AST::ForStmt
      lowered.concat(lower_async_cf_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers: active_defers + local_defers))
    when AST::MatchStmt
      lowered.concat(lower_async_cf_match_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers: active_defers + local_defers, loop_flow: nested_loop_flow(loop_flow, local_defers)))
    when AST::UnsafeStmt
      lowered.concat(lower_async_cf_statements(statement.body, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers: active_defers + local_defers, loop_flow: nested_loop_flow(loop_flow, local_defers)))
    when AST::DeferStmt
      local_defers << lower_async_defer_cleanup(statement, env:, async_info:)
    when AST::PassStmt
      nil
    when AST::BreakStmt
      if loop_flow
        lowered.concat(lower_async_loop_exit(loop_flow[:break_target], local_defers, loop_flow[:break_defers], frame_expr:, raw_frame_expr:, async_info:))
      else
        lowered << IR::BreakStmt.new
      end
    when AST::ContinueStmt
      if loop_flow
        lowered.concat(lower_async_loop_exit(loop_flow[:continue_target], local_defers, loop_flow[:continue_defers], frame_expr:, raw_frame_expr:, async_info:))
      else
        lowered << IR::ContinueStmt.new
      end
    when AST::StaticAssert
      lowered.concat(lower_static_assert(statement))
    else
      raise LoweringError.new("unsupported async cf statement #{statement.class.name}", line: 0, column: 0, path: @ctx.current_analysis_path)
    end
  end

  unless cfg_block_always_terminates?(statements)
    lowered.concat(lower_async_cleanup_entries(local_defers, [], frame_expr:, raw_frame_expr:, async_info:))
  end
  lowered
end

#lower_async_cf_while_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 341

def lower_async_cf_while_stmt(statement, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow:)
  continue_label = fresh_c_temp_name(env, "loop_continue")
  break_label = fresh_c_temp_name(env, "loop_break")
  condition_setup, prepared_cond = prepare_expression_for_inline_lowering(statement.condition, env:)
  condition = lower_contextual_expression(prepared_cond, env:, expected_type: @ctx.types.fetch("bool"))
  inner_loop_flow = loop_flow(break_target: loop_exit_break(break_label), continue_target: loop_exit_continue(continue_label))
  body = lower_async_body(statement.body, env: duplicate_env(env), frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers:, loop_flow: inner_loop_flow)
  body << IR::LabelStmt.new(name: continue_label) if contains_label_target?(body, continue_label)

  build_async_while_with_condition_setup(condition_setup, condition, body, break_label)
end

#lower_async_cleanup_entries(local_defers, outer_defers, frame_expr:, raw_frame_expr:, async_info:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1251

def lower_async_cleanup_entries(local_defers, outer_defers, frame_expr:, raw_frame_expr:, async_info:)
  cleanup_entries = local_defers.reverse + outer_defers.reverse
  cleanup_entries.flat_map do |cleanup_entry|
    next [] if cleanup_entry[:body].empty?

    cleanup_env = duplicate_env(cleanup_entry[:env])
    lower_async_body(
      cleanup_entry[:body],
      env: cleanup_env,
      frame_expr:,
      raw_frame_expr:,
      resume_linkage_name: async_info.fetch(:resume_linkage_name),
      async_info:,
      active_defers: [],
      loop_flow: nil,
    )
  end
end

#lower_async_collection_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers: []) ⇒ Object

Raises:



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 836

def lower_async_collection_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers: [])
  iterable_type = infer_expression_type(statement.iterable, env:)
  element_type = collection_loop_type(iterable_type)
  raise LoweringError.new("for loop expects start..stop, array[T, N], or span[T], got #{iterable_type}", line: 0, column: 0, path: @ctx.current_analysis_path) unless element_type

  iterable_setup, prepared_iterable = prepare_expression_for_inline_lowering(statement.iterable, env:, expected_type: iterable_type)
  iterable_linkage_name = fresh_c_temp_name(env, "for_items")
  index_linkage_name = fresh_c_temp_name(env, "for_index")
  continue_label = fresh_c_temp_name(env, "loop_continue")
  break_label = fresh_c_temp_name(env, "loop_break")
  iterable_ref = IR::Name.new(name: iterable_linkage_name, type: iterable_type, pointer: false)
  index_ref = IR::Name.new(name: index_linkage_name, type: @ctx.types.fetch("ptr_uint"), pointer: false)

  item_value = if array_type?(iterable_type)
                  IR::Index.new(receiver: iterable_ref, index: index_ref, type: element_type)
                else
                  data_ref = IR::Member.new(receiver: iterable_ref, member: "data", type: pointer_to(element_type))
                  IR::Index.new(receiver: data_ref, index: index_ref, type: element_type)
                end
  stop_value = if array_type?(iterable_type)
                  IR::IntegerLiteral.new(value: array_length(iterable_type), type: @ctx.types.fetch("ptr_uint"))
                else
                  IR::Member.new(receiver: iterable_ref, member: "len", type: @ctx.types.fetch("ptr_uint"))
                end

  while_env = duplicate_env(env)
  current_actual_scope(while_env[:scopes])[statement.name] = local_binding(
    type: element_type, linkage_name: c_local_name(statement.name), mutable: false, pointer: false
  )
  body = [IR::LocalDecl.new(name: statement.name, linkage_name: c_local_name(statement.name), type: element_type, value: item_value)]
  body.concat(lower_async_non_await_statements(
    statement.body,
    env: while_env,
    frame_expr:,
    raw_frame_expr:,
    async_info:,
    active_defers:,
    loop_flow: loop_flow(break_target: loop_exit_break(break_label), continue_target: loop_exit_continue(continue_label)),
  ))
  body << IR::LabelStmt.new(name: continue_label) if contains_label_target?(body, continue_label)

  for_statement = IR::ForStmt.new(
    init: IR::LocalDecl.new(name: index_linkage_name, linkage_name: index_linkage_name, type: @ctx.types.fetch("ptr_uint"), value: IR::IntegerLiteral.new(value: 0, type: @ctx.types.fetch("ptr_uint"))),
    condition: IR::Binary.new(operator: "<", left: index_ref, right: stop_value, type: @ctx.types.fetch("bool")),
    post: IR::Assignment.new(target: index_ref, operator: "+=", value: IR::IntegerLiteral.new(value: 1, type: @ctx.types.fetch("ptr_uint"))),
    body:,
  )

  stmts = [
    *iterable_setup,
    IR::LocalDecl.new(name: iterable_linkage_name, linkage_name: iterable_linkage_name, type: iterable_type, value: lower_expression(prepared_iterable, env:, expected_type: iterable_type)),
    for_statement,
  ]
  stmts << IR::LabelStmt.new(name: break_label) if contains_label_target?(body, break_label)
  IR::BlockStmt.new(body: stmts)
end

#lower_async_defer_cleanup(statement, env:, async_info:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1239

def lower_async_defer_cleanup(statement, env:, async_info:)
  body = if statement.body
            statement.body
          elsif statement.expression
            [AST::ExpressionStmt.new(expression: statement.expression, line: statement.line)]
          else
            []
          end

  { body:, env: snapshot_env(env) }
end

#lower_async_expression_statement(statement, env:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1049

def lower_async_expression_statement(statement, env:)
  lowered = []
  expression_expected_type = if statement.expression.is_a?(AST::UnaryOp) && statement.expression.operator == "?"
                                nil
                              else
                                infer_expression_type(statement.expression, env:)
                              end
  prepared_setup, prepared_expression = prepare_expression_for_inline_lowering(
    statement.expression,
    env:,
    expected_type: expression_expected_type,
    allow_root_statement_foreign: true,
    allow_void_propagation: true,
  )
  lowered.concat(prepared_setup)

  if prepared_expression && (foreign_call = foreign_call_info(prepared_expression, env))
    setup, = lower_foreign_call_statement(
      foreign_call,
      env:,
      expected_type: foreign_call[:binding].type.return_type,
      statement_position: true,
      discard_result: true,
    )
    lowered.concat(setup)
  elsif prepared_expression
    lowered << IR::ExpressionStmt.new(expression: lower_expression(prepared_expression, env:), line: statement.line, path: @ctx.current_analysis_path)
  end

  lowered
end

#lower_async_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers: []) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 778

def lower_async_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers: [])
  return lower_async_parallel_collection_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers:) if statement.parallel?

  return lower_async_range_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers:) if range_iterable?(statement.iterable)

  lower_async_collection_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers:)
end

#lower_async_local_decl_statement(statement, field_info:, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers: [], loop_flow: nil) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 89

def lower_async_local_decl_statement(statement, field_info:, env:, frame_expr:, raw_frame_expr:, resume_linkage_name:, async_info:, active_defers: [], loop_flow: nil)
  lowered = []
  type = field_info[:type]
  storage_type = field_info[:storage_type]
  target = async_frame_field_expression(frame_expr, field_info[:field_name], storage_type)
  prepared_setup = []
  prepared_value = statement.value

  if statement.value
    cleanup_start = (env[:prepared_expression_cleanups] ||= []).length
    prepared_setup, prepared_value = prepare_expression_for_inline_lowering(
      statement.value,
      env:,
      expected_type: storage_type,
      allow_root_statement_foreign: true,
    )
    cleanup_count = (env[:prepared_expression_cleanups] || []).length - cleanup_start
    if cleanup_count.positive?
      async_info[:format_str_fields][field_info[:field_name]] = storage_type
      env[:prepared_expression_cleanups].slice!(cleanup_start, cleanup_count)
    end
    lowered.concat(prepared_setup)
  end

  if prepared_value && (foreign_call = foreign_call_info(prepared_value, env))
    setup, value, call_type, release_assignments, cleanup_statements = lower_foreign_call_components(
      foreign_call,
      env:,
      expected_type: storage_type,
      statement_position: false,
    )
    lowered.concat(setup)
    raise LoweringError.new("foreign call used to initialize #{statement.name} must return a value", line: 0, column: 0, path: @ctx.current_analysis_path) if call_type == @ctx.types.fetch("void")
    raise LoweringError.new("consuming foreign calls must return void", line: 0, column: 0, path: @ctx.current_analysis_path) unless release_assignments.empty?

    lowered << IR::Assignment.new(target:, operator: "=", value:)
    lowered.concat(cleanup_statements)
  else
    value = if prepared_value
              lower_contextual_expression(
                prepared_value,
                env:,
                expected_type: storage_type,
                contextual_int_to_float: statement.type && contextual_int_to_float_target?(type),
              )
            else
              IR::ZeroInit.new(type: storage_type)
            end
    lowered << IR::Assignment.new(target:, operator: "=", value:)
  end

  if statement.else_body
    else_env = duplicate_env(env)
    if statement.else_binding
      current_actual_scope(else_env[:scopes])[statement.else_binding.name] = local_binding(
        type: let_else_error_type(storage_type),
        storage_type:,
        linkage_name: async_frame_field_c_name(field_info[:field_name]),
        mutable: false,
        pointer: false,
        projection: :result_failure_error,
      )
    end
    else_body = lower_async_body(
      statement.else_body,
      env: else_env,
      frame_expr:,
      raw_frame_expr:,
      resume_linkage_name:,
      async_info:,
      active_defers:,
      loop_flow:,
    )
    lowered << IR::IfStmt.new(
      condition: let_else_failure_condition(target, storage_type),
      then_body: else_body,
      else_body: nil,
    )
  end

  lowered
end

#lower_async_loop_exit(target, local_defers, outer_defers, frame_expr:, raw_frame_expr:, async_info:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1378

def lower_async_loop_exit(target, local_defers, outer_defers, frame_expr:, raw_frame_expr:, async_info:)
  cleanup = lower_async_cleanup_entries(local_defers, outer_defers, frame_expr:, raw_frame_expr:, async_info:)
  if cleanup.empty?
    [loop_exit_statement(target, local_defers:, outer_defers:)]
  else
    label = target[:label]
    raise LoweringError.new("structured loop exits with cleanup are unsupported", line: 0, column: 0, path: @ctx.current_analysis_path) unless label

    cleanup + [IR::GotoStmt.new(label:)]
  end
end

#lower_async_non_await_statements(statements, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers: [], loop_flow: nil) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 595

def lower_async_non_await_statements(statements, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers: [], loop_flow: nil)
  local_env = duplicate_env(env)
  lowered = []
  local_defers = []
  local_env[:return_context] = async_return_context(
    return_type: async_info[:result_type],
    active_defers:,
    local_defers:,
    frame_expr:,
    raw_frame_expr:,
    async_info:,
  )

  statements.each do |statement|
    case statement
    when AST::LocalDecl
      else_env = duplicate_env(local_env) if statement.else_body
      type, storage_type = async_local_decl_types(statement, env: local_env)
      linkage_name = c_local_name(statement.name)
      if statement.value
        prepared_setup, prepared_value = prepare_expression_for_inline_lowering(
          statement.value, env: local_env, expected_type: storage_type, allow_root_statement_foreign: true
        )
        lowered.concat(prepared_setup)
        value = lower_contextual_expression(
          prepared_value, env: local_env, expected_type: storage_type,
          contextual_int_to_float: statement.type && contextual_int_to_float_target?(type)
        )
      else
        value = IR::ZeroInit.new(type: storage_type)
      end
      lowered << IR::LocalDecl.new(name: statement.name, linkage_name:, type: storage_type, value:)
      current_actual_scope(local_env[:scopes])[statement.name] = local_binding(type:, storage_type:, linkage_name:, mutable: statement.kind == :var, pointer: false)
      if statement.else_body
        else_body = lower_async_non_await_statements(
          statement.else_body,
          env: else_env,
          frame_expr:,
          raw_frame_expr:,
          async_info:,
          active_defers: active_defers + local_defers,
          loop_flow: nested_loop_flow(loop_flow, local_defers),
        )
        lowered << IR::IfStmt.new(
          condition: IR::Binary.new(
            operator: "==",
            left: IR::Name.new(name: linkage_name, type: storage_type, pointer: false),
            right: IR::NullLiteral.new(type: storage_type),
            type: @ctx.types.fetch("bool"),
          ),
          then_body: else_body,
          else_body: nil,
        )
      end
    when AST::Assignment
      lowered.concat(lower_async_assignment_statement(statement, env: local_env))
    when AST::ExpressionStmt
      lowered.concat(lower_async_expression_statement(statement, env: local_env))
    when AST::ReturnStmt
      lowered.concat(lower_async_return_statement(statement, env: local_env, frame_expr:, raw_frame_expr:, async_info:, cleanup: lower_async_cleanup_entries(local_defers, active_defers, frame_expr:, raw_frame_expr:, async_info:)))
    when AST::IfStmt
      branch_entries = statement.branches.map do |branch|
        condition_setup, prepared_cond = prepare_expression_for_inline_lowering(
          branch.condition, env: local_env, expected_type: @ctx.types.fetch("bool")
        )
        then_body = lower_async_non_await_statements(
          branch.body, env: local_env, frame_expr:, raw_frame_expr:, async_info:, active_defers: active_defers + local_defers, loop_flow: nested_loop_flow(loop_flow, local_defers)
        )
        [condition_setup, lower_expression(prepared_cond, env: local_env, expected_type: @ctx.types.fetch("bool")), then_body]
      end
      else_body = statement.else_body ? lower_async_non_await_statements(
        statement.else_body, env: local_env, frame_expr:, raw_frame_expr:, async_info:, active_defers: active_defers + local_defers, loop_flow: nested_loop_flow(loop_flow, local_defers)
      ) : nil
      nested = else_body || []
      branch_entries.reverse_each do |cond_setup, cond, then_body|
        nested = [*cond_setup, IR::IfStmt.new(condition: cond, then_body:, else_body: nested.empty? ? nil : nested)]
      end
      lowered.concat(nested)
    when AST::MatchStmt
      scrutinee_type = infer_expression_type(statement.expression, env: local_env)
      expr_setup, prepared_expr = prepare_expression_for_inline_lowering(
        statement.expression, env: local_env, expected_type: scrutinee_type
      )
      lowered.concat(expr_setup)
      expr = lower_expression(prepared_expr, env: local_env, expected_type: scrutinee_type)
      arm_loop_flow = switch_loop_flow(loop_flow, local_defers)
      if scrutinee_type.is_a?(Types::Variant)
        if statement.arms.any? { |arm| arm.binding_name && !wildcard_arm_pattern?(arm.pattern) } &&
            !duplicable_foreign_argument_expression?(expr)
          scrutinee_linkage_name = fresh_c_temp_name(local_env, "match_value")
          lowered << IR::LocalDecl.new(name: scrutinee_linkage_name, linkage_name: scrutinee_linkage_name, type: scrutinee_type, value: expr)
          expr = IR::Name.new(name: scrutinee_linkage_name, type: scrutinee_type, pointer: false)
        end

        kind_type = @ctx.types.fetch("int")
        kind_expr = IR::Member.new(receiver: expr, member: "kind", type: kind_type)
        cases = statement.arms.map do |arm|
          arm_env, binding_decl = async_variant_match_arm_binding(arm, expr, scrutinee_type, env: local_env)
          arm_body = lower_async_non_await_statements(
            arm.body, env: arm_env, frame_expr:, raw_frame_expr:, async_info:, active_defers: active_defers + local_defers, loop_flow: arm_loop_flow
          )
          body = [binding_decl, *arm_body].compact
          if wildcard_arm_pattern?(arm.pattern)
            IR::SwitchDefaultCase.new(body: body)
          else
            arm_name = variant_match_arm_name_from_pattern(arm.pattern)
            IR::SwitchCase.new(value: IR::Name.new(name: enum_member_c_name(scrutinee_type, "kind_#{arm_name}"), type: kind_type, pointer: false), body: body)
          end
        end
        lowered << IR::SwitchStmt.new(expression: kind_expr, cases:, exhaustive: true)
      else
        cases = statement.arms.map do |arm|
          arm_body = lower_async_non_await_statements(
            arm.body, env: local_env, frame_expr:, raw_frame_expr:, async_info:, active_defers: active_defers + local_defers, loop_flow: arm_loop_flow
          )
          if wildcard_arm_pattern?(arm.pattern)
            IR::SwitchDefaultCase.new(body: arm_body)
          else
            value = lower_expression(arm.pattern, env: local_env, expected_type: scrutinee_type)
            IR::SwitchCase.new(value:, body: arm_body)
          end
        end
        lowered << IR::SwitchStmt.new(expression: expr, cases:, exhaustive: true)
      end
    when AST::WhileStmt
      lowered << lower_async_while_stmt(statement, env: local_env, frame_expr:, raw_frame_expr:, async_info:, active_defers: active_defers + local_defers)
    when AST::ForStmt
      lowered << lower_async_for_stmt(statement, env: local_env, frame_expr:, raw_frame_expr:, async_info:, active_defers: active_defers + local_defers)
    when AST::DeferStmt
      local_defers << lower_async_defer_cleanup(statement, env: local_env, async_info:)
    when AST::PassStmt
      nil
    when AST::BreakStmt
      if loop_flow
        lowered.concat(lower_async_loop_exit(loop_flow[:break_target], local_defers, loop_flow[:break_defers], frame_expr:, raw_frame_expr:, async_info:))
      else
        lowered << IR::BreakStmt.new
      end
    when AST::ContinueStmt
      if loop_flow
        lowered.concat(lower_async_loop_exit(loop_flow[:continue_target], local_defers, loop_flow[:continue_defers], frame_expr:, raw_frame_expr:, async_info:))
      else
        lowered << IR::ContinueStmt.new
      end
    when AST::UnsafeStmt
      lowered.concat(lower_async_non_await_statements(
        statement.body, env: local_env, frame_expr:, raw_frame_expr:, async_info:, active_defers: active_defers + local_defers, loop_flow: nested_loop_flow(loop_flow, local_defers)
      ))
    when AST::StaticAssert
      lowered << lower_static_assert(statement, env: local_env)
    else
      raise LoweringError.new("unsupported async non-await statement #{statement.class.name}", line: 0, column: 0, path: @ctx.current_analysis_path)
    end
  end

  unless cfg_block_always_terminates?(statements)
    lowered.concat(lower_async_cleanup_entries(local_defers, [], frame_expr:, raw_frame_expr:, async_info:))
  end
  lowered
end

#lower_async_parallel_collection_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers: []) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 893

def lower_async_parallel_collection_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers: [])
  infos = statement.bindings.each_with_index.map do |binding, index|
    iterable = statement.iterables[index]
    iterable_type = infer_expression_type(iterable, env:)
    element_type = collection_loop_type(iterable_type)
    raise LoweringError.new("parallel for loops expect arrays or spans for each iterable, got #{iterable_type}", line: 0, column: 0, path: @ctx.current_analysis_path) unless element_type

    {
      binding:,
      iterable:,
      iterable_type:,
      element_type:,
      binding_type: collection_loop_binding_type(iterable_type, element_type) || element_type,
    }
  end

  iterable_entries = infos.map do |info|
    setup, prepared_iterable = prepare_expression_for_inline_lowering(info[:iterable], env:, expected_type: info[:iterable_type])
    linkage_name = fresh_c_temp_name(env, "for_items")
    info.merge(
      setup:,
      prepared_iterable:,
      iterable_linkage_name: linkage_name,
      iterable_ref: IR::Name.new(name: linkage_name, type: info[:iterable_type], pointer: false),
    )
  end

  index_linkage_name = fresh_c_temp_name(env, "for_index")
  continue_label = fresh_c_temp_name(env, "loop_continue")
  break_label = fresh_c_temp_name(env, "loop_break")
  index_ref = IR::Name.new(name: index_linkage_name, type: @ctx.types.fetch("ptr_uint"), pointer: false)
  stop_value = collection_loop_stop_value(iterable_entries.first[:iterable_ref], iterable_entries.first[:iterable_type])

  while_env = duplicate_env(env)
  body = iterable_entries.map do |entry|
    item_value = collection_loop_item_value(entry[:iterable_ref], entry[:iterable_type], index_ref, entry[:element_type])
    loop_item_value = if ref_type?(entry[:binding_type])
                        IR::AddressOf.new(expression: item_value, type: entry[:binding_type])
                      else
                        item_value
                      end
    binding = entry[:binding]
    current_actual_scope(while_env[:scopes])[binding.name] = local_binding(type: entry[:binding_type], linkage_name: c_local_name(binding.name), mutable: false, pointer: false)
    IR::LocalDecl.new(name: binding.name, linkage_name: c_local_name(binding.name), type: entry[:binding_type], value: loop_item_value)
  end
  body.concat(lower_async_non_await_statements(
    statement.body,
    env: while_env,
    frame_expr:,
    raw_frame_expr:,
    async_info:,
    active_defers:,
    loop_flow: loop_flow(break_target: loop_exit_break(break_label), continue_target: loop_exit_continue(continue_label)),
  ))
  body << IR::LabelStmt.new(name: continue_label) if contains_label_target?(body, continue_label)

  length_checks = iterable_entries.drop(1).map do |entry|
    IR::IfStmt.new(
      condition: IR::Binary.new(
        operator: "!=",
        left: collection_loop_stop_value(entry[:iterable_ref], entry[:iterable_type]),
        right: stop_value,
        type: @ctx.types.fetch("bool"),
      ),
      then_body: [lower_fatal_statement("parallel for iterables must have matching lengths", env:)],
      else_body: nil,
    )
  end

  for_statement = IR::ForStmt.new(
    init: IR::LocalDecl.new(name: index_linkage_name, linkage_name: index_linkage_name, type: @ctx.types.fetch("ptr_uint"), value: IR::IntegerLiteral.new(value: 0, type: @ctx.types.fetch("ptr_uint"))),
    condition: IR::Binary.new(operator: "<", left: index_ref, right: stop_value, type: @ctx.types.fetch("bool")),
    post: IR::Assignment.new(target: index_ref, operator: "+=", value: IR::IntegerLiteral.new(value: 1, type: @ctx.types.fetch("ptr_uint"))),
    body:,
  )

  stmts = [
    *iterable_entries.flat_map { |entry| entry[:setup] },
    *iterable_entries.map do |entry|
      IR::LocalDecl.new(name: entry[:iterable_linkage_name], linkage_name: entry[:iterable_linkage_name], type: entry[:iterable_type], value: lower_expression(entry[:prepared_iterable], env:, expected_type: entry[:iterable_type]))
    end,
    *length_checks,
    for_statement,
  ]
  stmts << IR::LabelStmt.new(name: break_label) if contains_label_target?(body, break_label)
  IR::BlockStmt.new(body: stmts)
end

#lower_async_range_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers: []) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 786

def lower_async_range_for_stmt(statement, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers: [])
  loop_type = infer_range_loop_type(statement.iterable, env:)
  start_expr = range_start_of(statement.iterable)
  stop_expr = range_end_of(statement.iterable)
  start_setup, prepared_start = prepare_expression_for_inline_lowering(start_expr, env:, expected_type: loop_type)
  stop_setup, prepared_stop = prepare_expression_for_inline_lowering(stop_expr, env:, expected_type: loop_type)
  index_linkage_name = c_local_name(statement.name)
  stop_linkage_name = fresh_c_temp_name(env, "for_stop")
  continue_label = fresh_c_temp_name(env, "loop_continue")
  break_label = fresh_c_temp_name(env, "loop_break")
  index_ref = IR::Name.new(name: index_linkage_name, type: loop_type, pointer: false)
  inline_stop = stop_setup.empty? && compile_time_numeric_const_expression?(prepared_stop)
  stop_value = if inline_stop
                  lower_expression(prepared_stop, env:, expected_type: loop_type)
                else
                  IR::Name.new(name: stop_linkage_name, type: loop_type, pointer: false)
                end

  while_env = duplicate_env(env)
  current_actual_scope(while_env[:scopes])[statement.name] = local_binding(
    type: loop_type, linkage_name: index_linkage_name, mutable: false, pointer: false
  )
  body = lower_async_non_await_statements(
    statement.body,
    env: while_env,
    frame_expr:,
    raw_frame_expr:,
    async_info:,
    active_defers:,
    loop_flow: loop_flow(break_target: loop_exit_break(break_label), continue_target: loop_exit_continue(continue_label)),
  )
  body << IR::LabelStmt.new(name: continue_label) if contains_label_target?(body, continue_label)

  for_statement = IR::ForStmt.new(
    init: IR::LocalDecl.new(name: statement.name, linkage_name: index_linkage_name, type: loop_type, value: lower_expression(prepared_start, env:, expected_type: loop_type)),
    condition: IR::Binary.new(operator: "<", left: index_ref, right: stop_value, type: @ctx.types.fetch("bool")),
    post: IR::Assignment.new(target: index_ref, operator: "+=", value: IR::IntegerLiteral.new(value: 1, type: loop_type)),
    body:,
  )

  stmts = [
    *start_setup,
    *stop_setup,
    *(inline_stop ? [] : [IR::LocalDecl.new(name: stop_linkage_name, linkage_name: stop_linkage_name, type: loop_type, value: lower_expression(prepared_stop, env:, expected_type: loop_type))]),
    for_statement,
  ]
  stmts << IR::LabelStmt.new(name: break_label) if contains_label_target?(body, break_label)
  IR::BlockStmt.new(body: stmts)
end

#lower_async_return_statement(statement, env:, frame_expr:, raw_frame_expr:, async_info:, cleanup: []) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 1080

def lower_async_return_statement(statement, env:, frame_expr:, raw_frame_expr:, async_info:, cleanup: [])
  lowered = []
  value = nil
  prepared_setup = []
  prepared_value = statement.value

  if statement.value
    prepared_setup, prepared_value = prepare_expression_for_inline_lowering(
      statement.value,
      env:,
      expected_type: async_info[:result_type],
      allow_root_statement_foreign: true,
    )
    lowered.concat(prepared_setup)
  end

  if prepared_value && (foreign_call = foreign_call_info(prepared_value, env))
    setup, value = lower_foreign_call_statement(foreign_call, env:, expected_type: async_info[:result_type], statement_position: false)
    lowered.concat(setup)
  elsif prepared_value
    value = lower_contextual_expression(
      prepared_value,
      env:,
      expected_type: async_info[:result_type],
      contextual_int_to_float: contextual_int_to_float_target?(async_info[:result_type]),
    )
  end

  if async_info[:result_type] != @ctx.types.fetch("void") && value && cleanup.any? && !cleanup_safe_return_expression?(prepared_value)
    lowered << IR::Assignment.new(
      target: async_frame_field_expression(frame_expr, "result", async_info[:result_type]),
      operator: "=",
      value: value,
    )
    lowered.concat(cleanup)
    lowered.concat(async_complete_statements(frame_expr:, raw_frame_expr:, async_info:, value: nil, result_already_stored: true))
  else
    lowered.concat(cleanup)
    lowered.concat(async_complete_statements(frame_expr:, raw_frame_expr:, async_info:, value:))
  end
  lowered
end

#lower_async_while_stmt(statement, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers: []) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 756

def lower_async_while_stmt(statement, env:, frame_expr:, raw_frame_expr:, async_info:, active_defers: [])
  continue_label = fresh_c_temp_name(env, "loop_continue")
  break_label = fresh_c_temp_name(env, "loop_break")
  condition_setup, prepared_cond = prepare_expression_for_inline_lowering(
    statement.condition, env:, expected_type: @ctx.types.fetch("bool")
  )
  body = lower_async_non_await_statements(
    statement.body,
    env: duplicate_env(env),
    frame_expr:,
    raw_frame_expr:,
    async_info:,
    active_defers:,
    loop_flow: loop_flow(break_target: loop_exit_break(break_label), continue_target: loop_exit_continue(continue_label)),
  )
  body << IR::LabelStmt.new(name: continue_label) if contains_label_target?(body, continue_label)
  cond = lower_expression(prepared_cond, env:, expected_type: @ctx.types.fetch("bool"))

  stmts = build_async_while_with_condition_setup(condition_setup, cond, body, break_label)
  IR::BlockStmt.new(body: stmts)
end

#lower_contained_task_release_statements(value_expr, type) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 5

def lower_contained_task_release_statements(value_expr, type)
  return [] unless contains_task_type?(type)

  void_type = @ctx.types.fetch("void")

  case type
  when Types::Task
    task_frame_expr = IR::Member.new(receiver: value_expr, member: "frame", type: type.field("frame"))
    release_call = IR::ExpressionStmt.new(
      expression: IR::Call.new(
        callee: IR::Member.new(receiver: value_expr, member: "release", type: type.field("release")),
        arguments: [task_frame_expr],
        type: void_type,
      ),
    )
    [IR::IfStmt.new(condition: task_frame_expr, then_body: [release_call], else_body: nil)]

  when Types::Struct, Types::StructInstance, Types::Union, Types::GenericStructDefinition, Types::VariantArmPayload
    statements = []
    type.fields.each do |field_name, field_type|
      next unless contains_task_type?(field_type)

      field_expr = IR::Member.new(receiver: value_expr, member: field_name, type: field_type)
      statements.concat(lower_contained_task_release_statements(field_expr, field_type))
    end
    statements

  when Types::VariantInstance
    if type.definition.name == "Option" && type.arguments.any? { |a| contains_task_type?(a) }
      lower_opt_task_value_release_statements(value_expr, type.arguments.first)
    else
      []
    end

  when Types::Variant, Types::GenericVariantDefinition
    statements = []
    type.arms.each do |arm_name, arm_fields|
      arm_fields.each do |field_name, field_type|
        next unless contains_task_type?(field_type)
        data_expr = IR::Member.new(receiver: value_expr, member: "data", type: nil)
        arm_expr = IR::Member.new(receiver: data_expr, member: arm_name, type: nil)
        field_expr = IR::Member.new(receiver: arm_expr, member: field_name, type: field_type)
        statements.concat(lower_contained_task_release_statements(field_expr, field_type))
      end
    end
    statements

  when Types::GenericInstance
    if type.name == "Option" && type.arguments.any? { |a| contains_task_type?(a) }
      lower_opt_task_value_release_statements(value_expr, type.arguments.first)
    else
      []
    end

  when Types::Nullable
    lower_contained_task_release_statements(value_expr, type.base)

  else
    []
  end
end

#lower_opt_task_value_release_statements(value_expr, task_type) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 67

def lower_opt_task_value_release_statements(value_expr, task_type)
  int_type = @ctx.types.fetch("int")
  kind_expr = IR::Member.new(receiver: value_expr, member: "kind", type: int_type)
  some_check = IR::Binary.new(
    operator: "==",
    left: kind_expr,
    right: IR::IntegerLiteral.new(value: 0, type: int_type),
    type: @ctx.types.fetch("bool"),
  )
  data_expr = IR::Member.new(receiver: value_expr, member: "data", type: nil)
  some_payload_expr = IR::Member.new(receiver: data_expr, member: "some", type: nil)
  task_value_expr = IR::Member.new(receiver: some_payload_expr, member: "value", type: task_type)
  release_body = lower_contained_task_release_statements(task_value_expr, task_type)
  none_assignment = IR::Assignment.new(
    target: kind_expr,
    operator: "=",
    value: IR::IntegerLiteral.new(value: 1, type: int_type),
  )
  then_body = release_body + [none_assignment]
  [IR::IfStmt.new(condition: some_check, then_body:, else_body: nil)]
end

#lower_range_call(iterable, env:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 363

def lower_range_call(iterable, env:)
  loop_type = infer_range_loop_type(iterable, env:)
  start_expr_ast = range_start_of(iterable)
  stop_expr_ast = range_end_of(iterable)
  start_ir = lower_expression(start_expr_ast, env:, expected_type: loop_type)
  stop_ir = lower_expression(stop_expr_ast, env:, expected_type: loop_type)
  [start_ir, stop_ir, false]
end

#normalize_async_assignment_target(target, counter, env:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/normalization.rb', line 190

def normalize_async_assignment_target(target, counter, env:)
  case target
  when AST::Identifier
    [[], target]
  when AST::MemberAccess
    receiver_setup, receiver = normalize_async_expression(target.receiver, counter, env:)
    [receiver_setup, AST::MemberAccess.new(receiver:, member: target.member)]
  when AST::IndexAccess
    receiver_setup, receiver = normalize_async_expression(target.receiver, counter, env:)
    index_setup, index = normalize_async_expression(target.index, counter, env:)
    [receiver_setup + index_setup, AST::IndexAccess.new(receiver:, index:)]
  when AST::Call
    if read_call?(target)
      setup = []
      normalized_args = target.arguments.map do |arg|
        arg_setup, value = normalize_async_expression(arg.value, counter, env:)
        setup.concat(arg_setup)
        AST::Argument.new(name: arg.name, value:)
      end
      [setup, AST::Call.new(callee: target.callee, arguments: normalized_args)]
    else
      raise LoweringError.new("unsupported assignment target #{target.class.name}", line: 0, column: 0, path: @ctx.current_analysis_path)
    end
  else
    raise LoweringError.new("unsupported assignment target #{target.class.name}", line: 0, column: 0, path: @ctx.current_analysis_path)
  end
end

#normalize_async_body(binding, statements) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/normalization.rb', line 5

def normalize_async_body(binding, statements)
  counter = { value: 0 }
  env = empty_env
  binding.body_params.each do |param_binding|
    env[:scopes].last[param_binding.name] = local_binding(
      type: param_binding.type,
      linkage_name: param_binding.name,
      mutable: param_binding.mutable,
      pointer: false,
    )
  end
  env[:return_context] = {
    return_type: binding.body_return_type,
    active_defers: [],
    local_defers: [],
    allow_return: true,
  }
  normalize_async_statements(statements, counter, env, return_type: binding.body_return_type)
end

#normalize_async_expression(expression, counter, env:, expected_type: nil) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/normalization.rb', line 218

def normalize_async_expression(expression, counter, env:, expected_type: nil)
  case expression
  when AST::AwaitExpr
    inner_setup, inner = normalize_async_expression(expression.expression, counter, env:)
    temp_name = fresh_async_temp_name(counter)
    [
      inner_setup + [AST::LocalDecl.new(kind: :let, name: temp_name, type: nil, value: AST::AwaitExpr.new(expression: inner))],
      AST::Identifier.new(name: temp_name),
    ]
  when AST::Call
    setup = []
    callee_setup, callee = normalize_async_expression(expression.callee, counter, env:)
    setup.concat(callee_setup)
    arguments = expression.arguments.map do |argument|
      argument_setup, value = normalize_async_expression(argument.value, counter, env:)
      setup.concat(argument_setup)
      AST::Argument.new(name: argument.name, value: value)
    end
    [setup, AST::Call.new(callee: callee, arguments: arguments)]
  when AST::Specialization
    setup = []
    callee_setup, callee = normalize_async_expression(expression.callee, counter, env:)
    setup.concat(callee_setup)
    arguments = expression.arguments.map do |argument|
      argument_setup, value = normalize_async_expression(argument.value, counter, env:)
      setup.concat(argument_setup)
      AST::TypeArgument.new(value: value)
    end
    [setup, AST::Specialization.new(callee: callee, arguments: arguments)]
  when AST::PrefixCast
    setup, expr = normalize_async_expression(expression.expression, counter, env:)
    [setup, AST::PrefixCast.new(target_type: expression.target_type, expression: expr)]
  when AST::UnaryOp
    setup, operand = normalize_async_expression(expression.operand, counter, env:, expected_type: expected_type)
    [setup, AST::UnaryOp.new(operator: expression.operator, operand: operand)]
  when AST::BinaryOp
    if %w[and or].include?(expression.operator)
      left_setup, left = normalize_async_expression(expression.left, counter, env:, expected_type: @ctx.types.fetch("bool"))
      right_setup, right = normalize_async_expression(expression.right, counter, env:, expected_type: @ctx.types.fetch("bool"))
      temp_name = fresh_async_temp_name(counter)

      temp_init = expression.operator == "and" ? AST::BooleanLiteral.new(value: false) : AST::BooleanLiteral.new(value: true)
      short_circuit_value = expression.operator == "and" ? AST::BooleanLiteral.new(value: false) : AST::BooleanLiteral.new(value: true)

      branch_body = right_setup + [AST::Assignment.new(target: AST::Identifier.new(name: temp_name), operator: "=", value: right)]
      else_body = [AST::Assignment.new(target: AST::Identifier.new(name: temp_name), operator: "=", value: short_circuit_value)]

      if expression.operator == "or"
        branch_body, else_body = else_body, branch_body
      end

      setup = [AST::LocalDecl.new(kind: :var, name: temp_name, type: nil, value: temp_init)]
      setup.concat(left_setup)
      setup << AST::IfStmt.new(branches: [AST::IfBranch.new(condition: left, body: branch_body)], else_body: else_body)
      return [setup, AST::Identifier.new(name: temp_name)]
    end

    left_setup, left = normalize_async_expression(expression.left, counter, env:)
    right_setup, right = normalize_async_expression(expression.right, counter, env:)
    [left_setup + right_setup, AST::BinaryOp.new(operator: expression.operator, left: left, right: right)]
  when AST::IfExpr
    condition_setup, condition = normalize_async_expression(expression.condition, counter, env:, expected_type: @ctx.types.fetch("bool"))
    result_type = infer_expression_type(expression, env:, expected_type:)
    then_setup, then_expression = normalize_async_expression(expression.then_expression, counter, env:, expected_type: result_type)
    else_setup, else_expression = normalize_async_expression(expression.else_expression, counter, env:, expected_type: result_type)

    return [[], AST::IfExpr.new(condition:, then_expression:, else_expression:)] if condition_setup.empty? && then_setup.empty? && else_setup.empty?

    temp_name = fresh_async_temp_name(counter)
    setup = condition_setup + [
      AST::LocalDecl.new(kind: :var, name: temp_name, type: ast_type_ref_for(result_type), value: nil),
      AST::IfStmt.new(
        branches: [AST::IfBranch.new(condition:, body: then_setup + [AST::Assignment.new(target: AST::Identifier.new(name: temp_name), operator: "=", value: then_expression)])],
        else_body: else_setup + [AST::Assignment.new(target: AST::Identifier.new(name: temp_name), operator: "=", value: else_expression)],
      ),
    ]
    [setup, AST::Identifier.new(name: temp_name)]
  when AST::MatchExpr
    expression_setup, normalized_expression = normalize_async_expression(expression.expression, counter, env:)
    result_type = infer_expression_type(expression, env:, expected_type:)
    scrutinee_type = infer_expression_type(expression.expression, env:)
    normalized_arms = expression.arms.map do |arm|
      arm_env = duplicate_env(env)
      bind_async_variant_match_arm_env!(arm_env, scrutinee_type, arm)
      pattern_setup, normalized_pattern = normalize_async_expression(arm.pattern, counter, env:)
      value_setup, normalized_value = normalize_async_expression(arm.value, counter, env: arm_env, expected_type: result_type)
      [pattern_setup, value_setup, AST::MatchExprArm.new(
        pattern: normalized_pattern,
        binding_name: arm.binding_name,
        binding_line: arm.binding_line,
        binding_column: arm.binding_column,
        value: normalized_value,
      )]
    end

    if expression_setup.empty? && normalized_arms.all? { |pattern_setup, value_setup, _arm| pattern_setup.empty? && value_setup.empty? }
      return [[], AST::MatchExpr.new(expression: normalized_expression, arms: normalized_arms.map(&:last), line: expression.line, column: expression.column, length: expression.length)]
    end

    temp_name = fresh_async_temp_name(counter)
    setup = expression_setup + [
      AST::LocalDecl.new(kind: :var, name: temp_name, type: ast_type_ref_for(result_type), value: nil),
      AST::MatchStmt.new(
        expression: normalized_expression,
        arms: normalized_arms.map do |pattern_setup, value_setup, arm|
          AST::MatchArm.new(
            pattern: arm.pattern,
            binding_name: arm.binding_name,
            binding_line: arm.binding_line,
            binding_column: arm.binding_column,
            body: pattern_setup + value_setup + [AST::Assignment.new(target: AST::Identifier.new(name: temp_name), operator: "=", value: arm.value)],
          )
        end,
        line: expression.line,
        column: expression.column,
        length: expression.length,
      ),
    ]
    [setup, AST::Identifier.new(name: temp_name)]
  when AST::UnsafeExpr
    normalize_async_expression(expression.expression, counter, env:, expected_type:)
  when AST::MemberAccess
    setup, receiver = normalize_async_expression(expression.receiver, counter, env:)
    [setup, AST::MemberAccess.new(receiver: receiver, member: expression.member)]
  when AST::IndexAccess
    receiver_setup, receiver = normalize_async_expression(expression.receiver, counter, env:)
    index_setup, index = normalize_async_expression(expression.index, counter, env:)
    [receiver_setup + index_setup, AST::IndexAccess.new(receiver: receiver, index: index)]
  when AST::RangeExpr
    start_setup, start_expr = normalize_async_expression(expression.start_expr, counter, env:)
    end_setup, end_expr = normalize_async_expression(expression.end_expr, counter, env:)
    [start_setup + end_setup, AST::RangeExpr.new(start_expr:, end_expr:, line: expression.line, column: expression.column)]
  when AST::FormatString
    setup = []
    parts = expression.parts.map do |part|
      if part.is_a?(AST::FormatExprPart)
        expression_setup, inner_expression = normalize_async_expression(part.expression, counter, env:)
        setup.concat(expression_setup)
        AST::FormatExprPart.new(expression: inner_expression, format_spec: part.format_spec)
      else
        part
      end
    end
    [setup, AST::FormatString.new(parts: parts)]
  else
    [[], expression]
  end
end

#normalize_async_if_branches(branches, else_body, counter, env, return_type:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/normalization.rb', line 179

def normalize_async_if_branches(branches, else_body, counter, env, return_type:)
  return else_body || [] if branches.empty?

  branch = branches.first
  condition_setup, condition = normalize_async_expression(branch.condition, counter, env:, expected_type: @ctx.types.fetch("bool"))
  then_env = duplicate_env(env)
  then_body = normalize_async_statements(branch.body, counter, then_env, return_type:)
  chained_else = normalize_async_if_branches(branches.drop(1), else_body, counter, env, return_type:)
  condition_setup + [AST::IfStmt.new(branches: [AST::IfBranch.new(condition:, body: then_body)], else_body: chained_else)]
end

#normalize_async_if_statement(statement, counter, env, return_type:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/normalization.rb', line 171

def normalize_async_if_statement(statement, counter, env, return_type:)
  else_body = if statement.else_body
                else_env = duplicate_env(env)
                normalize_async_statements(statement.else_body, counter, else_env, return_type:)
              end
  normalize_async_if_branches(statement.branches, else_body, counter, env, return_type:)
end

#normalize_async_statement(statement, counter, env, return_type:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/normalization.rb', line 29

def normalize_async_statement(statement, counter, env, return_type:)
  case statement
  when AST::LocalDecl
    if statement.value
      local_type, storage_type = async_local_decl_types(statement, env:)
      expected_type = statement.else_body ? storage_type : (statement.type ? resolve_type_ref(statement.type) : nil)
      setup, value = if statement.value.is_a?(AST::AwaitExpr)
        inner_setup, inner_expr = normalize_async_expression(statement.value.expression, counter, env:, expected_type: expected_type)
        [inner_setup, AST::AwaitExpr.new(expression: inner_expr)]
      else
        normalize_async_expression(statement.value, counter, env:, expected_type: expected_type)
      end
      else_body = if statement.else_body
        else_env = duplicate_env(env)
        normalize_async_statements(statement.else_body, counter, else_env, return_type:)
      end
      normalized = AST::LocalDecl.new(kind: statement.kind, name: statement.name, type: statement.type, value: value, else_binding: statement.else_binding, else_body:, line: statement.line)
      if bind_let_else_local?(statement)
        current_actual_scope(env[:scopes])[statement.name] = local_binding(
          type: local_type,
          storage_type:,
          linkage_name: statement.name,
          mutable: statement.kind == :var,
          pointer: false,
          projection: statement.else_body ? let_else_binding_projection(storage_type) : nil,
          const_value: statement.else_body ? nil : statement.kind == :let ? compile_time_const_value(statement.value, env:) : nil,
        )
      end
      return setup + [normalized]
    end

    local_type = resolve_type_ref(statement.type)
    current_actual_scope(env[:scopes])[statement.name] = local_binding(
      type: local_type,
      storage_type: local_type,
      linkage_name: statement.name,
      mutable: statement.kind == :var,
      pointer: false,
      const_value: nil,
    )
    [statement]
  when AST::Assignment
    target_setup, target = normalize_async_assignment_target(statement.target, counter, env:)
    return target_setup + [AST::Assignment.new(target:, operator: statement.operator, value: statement.value)] if statement.value.is_a?(AST::AwaitExpr)

    target_type = infer_expression_type(statement.target, env:)
    setup, value = normalize_async_expression(statement.value, counter, env:, expected_type: target_type)
    target_setup + setup + [AST::Assignment.new(target:, operator: statement.operator, value: value)]
  when AST::ExpressionStmt
    return [statement] if statement.expression.is_a?(AST::AwaitExpr)

    setup, expression = normalize_async_expression(statement.expression, counter, env:)
    setup + [AST::ExpressionStmt.new(expression: expression, line: statement.line)]
  when AST::ReturnStmt
    return [statement] unless statement.value
    return [statement] if statement.value.is_a?(AST::AwaitExpr)

    setup, value = normalize_async_expression(statement.value, counter, env:, expected_type: return_type)
    setup + [AST::ReturnStmt.new(value: value, line: statement.line)]
  when AST::IfStmt
    normalize_async_if_statement(statement, counter, env, return_type:)
  when AST::MatchStmt
    expr_setup, expression = normalize_async_expression(statement.expression, counter, env:)
    scrutinee_type = infer_expression_type(statement.expression, env:)
    arms = statement.arms.map do |arm|
      arm_env = duplicate_env(env)
      bind_async_variant_match_arm_env!(arm_env, scrutinee_type, arm)
      AST::MatchArm.new(pattern: arm.pattern, binding_name: arm.binding_name, body: normalize_async_statements(arm.body, counter, arm_env, return_type:))
    end
    expr_setup + [AST::MatchStmt.new(expression:, arms:)]
  when AST::WhileStmt
    condition_setup, condition = normalize_async_expression(statement.condition, counter, env:, expected_type: @ctx.types.fetch("bool"))
    body_env = duplicate_env(env)
    body = normalize_async_statements(statement.body, counter, body_env, return_type:)
    if condition_setup.empty?
      [AST::WhileStmt.new(condition:, body:)]
    else
      cond_name = fresh_async_temp_name(counter)
      condition_eval = condition_setup + [AST::LocalDecl.new(kind: :let, name: cond_name, type: ast_type_ref_for(@ctx.types.fetch("bool")), value: condition)]
      [
        AST::WhileStmt.new(
          condition: AST::BooleanLiteral.new(value: true),
          body: condition_eval + [
            AST::IfStmt.new(
              branches: [AST::IfBranch.new(condition: AST::UnaryOp.new(operator: "not", operand: AST::Identifier.new(name: cond_name)), body: [AST::BreakStmt.new])],
              else_body: nil,
            ),
            *body,
          ],
        ),
      ]
    end
  when AST::ForStmt
    original_iterable = statement.iterable
    loop_type = if range_iterable?(original_iterable)
                  infer_range_loop_type(original_iterable, env:)
                else
                  iterable_type = infer_expression_type(original_iterable, env:)
                  collection_loop_type(iterable_type)
                end
    for_env = duplicate_env(env)
    if statement.parallel?
      iterable_setups = []
      normalized_iterables = statement.iterables.map do |iterable|
        setup, normalized_iterable = normalize_async_expression(iterable, counter, env:)
        iterable_setups.concat(setup)
        normalized_iterable
      end
      statement.bindings.each_with_index do |binding, index|
        iterable_type = infer_expression_type(statement.iterables[index], env:)
        element_type = collection_loop_type(iterable_type)
        binding_type = collection_loop_binding_type(iterable_type, element_type) || element_type
        current_actual_scope(for_env[:scopes])[binding.name] = local_binding(type: binding_type, linkage_name: binding.name, mutable: false, pointer: false)
      end
      body = normalize_async_statements(statement.body, counter, for_env, return_type:)
      return iterable_setups + [AST::ForStmt.new(bindings: statement.bindings, iterables: normalized_iterables, body:, line: statement.line, column: statement.column)]
    end

    iterable_setup, iterable = normalize_async_expression(statement.iterable, counter, env:)
    current_actual_scope(for_env[:scopes])[statement.name] = local_binding(type: loop_type, linkage_name: statement.name, mutable: false, pointer: false)
    body = normalize_async_statements(statement.body, counter, for_env, return_type:)
    iterable_setup + [AST::ForStmt.new(bindings: statement.bindings, iterables: [iterable], body:, line: statement.line, column: statement.column)]
  when AST::UnsafeStmt
    unsafe_env = duplicate_env(env)
    [AST::UnsafeStmt.new(body: normalize_async_statements(statement.body, counter, unsafe_env, return_type:), line: statement.line, column: statement.column, length: statement.length)]
  when AST::DeferStmt
    cleanup_env = duplicate_env(env)
    cleanup_env[:return_context] = cleanup_env[:return_context]&.merge(allow_return: false)
    cleanup_body = if statement.body
                     normalize_async_statements(statement.body, counter, cleanup_env, return_type:)
                   else
                     expression_setup, expression = normalize_async_expression(statement.expression, counter, env: cleanup_env)
                     expression_setup + [AST::ExpressionStmt.new(expression:, line: statement.line)]
                   end
    [AST::DeferStmt.new(expression: nil, body: cleanup_body, line: statement.line, column: statement.column, length: statement.length)]
  when AST::BreakStmt, AST::ContinueStmt, AST::StaticAssert, AST::PassStmt
    [statement]
  else
    raise LoweringError.new("unsupported async statement #{statement.class.name}", line: 0, column: 0, path: @ctx.current_analysis_path)
  end
end

#normalize_async_statements(statements, counter, env, return_type:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/normalization.rb', line 25

def normalize_async_statements(statements, counter, env, return_type:)
  statements.flat_map { |statement| normalize_async_statement(statement, counter, env, return_type:) }
end

#reusable_async_await_task_field_name(task_expression, param_fields:, local_fields:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async/analysis.rb', line 209

def reusable_async_await_task_field_name(task_expression, param_fields:, local_fields:)
  return unless task_expression.is_a?(AST::Identifier)
  return local_fields.fetch(task_expression.name)[:field_name] if local_fields.key?(task_expression.name)
  return param_fields.fetch(task_expression.name)[:field_name] if param_fields.key?(task_expression.name)

  nil
end

#root_main_entrypoint_signature(binding) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/async.rb', line 235

def root_main_entrypoint_signature(binding)
  return nil unless @ctx.analysis == @program.root_analysis
  return nil unless binding.type.receiver_type.nil?
  return nil unless binding.name == "main"
  return nil unless binding.type_arguments.empty?

  return_type = binding.body_return_type
  return nil unless return_type == @ctx.types.fetch("int") || return_type == @ctx.types.fetch("void")

  params = binding.type.params
  return { kind: :none } if params.empty?

  if params.length == 1 && params.first.type.is_a?(Types::Span) && params.first.type.element_type == @ctx.types.fetch("str")
    return { kind: :span_str, args_type: params.first.type }
  end

  return nil unless params.length == 2
  return nil unless params[0].type == @ctx.types.fetch("int")

  argv_type = params[1].type
  return { kind: :raw_cstr_ptr, argv_type: } if argv_type == pointer_to(@ctx.types.fetch("cstr"))
  return { kind: :raw_char_ptr_ptr, argv_type: } if argv_type == pointer_to(pointer_to(@ctx.types.fetch("char")))

  nil
end

#statements_contain_await?(statements, async_info) ⇒ Boolean

Lowers a list of statements that contain no await anywhere, but live inside an async resume function. Return statements are lowered as async completions. All other control flow is lowered recursively.

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/lowering/async/lowering.rb', line 174

def statements_contain_await?(statements, async_info)
  statements.any? do |s|
    case s
    when AST::LocalDecl
      async_info[:await_fields].key?(s.value&.object_id) || async_expression_contains_await?(s.value) || (s.else_body && statements_contain_await?(s.else_body, async_info))
    when AST::Assignment
      async_info[:await_fields].key?(s.value&.object_id) || async_expression_contains_await?(s.target) || async_expression_contains_await?(s.value)
    when AST::ExpressionStmt
      async_info[:await_fields].key?(s.expression&.object_id) || async_expression_contains_await?(s.expression)
    when AST::ReturnStmt
      async_info[:await_fields].key?(s.value&.object_id) || async_expression_contains_await?(s.value)
    when AST::IfStmt
      s.branches.any? { |b| statements_contain_await?(b.body, async_info) } ||
        (s.else_body && statements_contain_await?(s.else_body, async_info))
    when AST::WhileStmt
      statements_contain_await?(s.body, async_info)
    when AST::ForStmt
      statements_contain_await?(s.body, async_info)
    when AST::MatchStmt
      s.arms.any? { |arm| statements_contain_await?(arm.body, async_info) }
    when AST::UnsafeStmt
      statements_contain_await?(s.body, async_info)
    when AST::DeferStmt
      (s.body && statements_contain_await?(s.body, async_info)) || (s.expression && async_expression_contains_await?(s.expression))
    else
      false
    end
  end
end