Module: MilkTea::LowererBlock

Included in:
Lowerer
Defined in:
lib/milk_tea/core/lowering/block.rb

Instance Method Summary collapse

Instance Method Details

#dereference_if_self_ref(field_expr, field_type, scrutinee_type) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 375

def dereference_if_self_ref(field_expr, field_type, scrutinee_type)
  if variant_self_referencing_field?(field_type, scrutinee_type)
    IR::Unary.new(operator: "*", operand: field_expr, type: field_type)
  else
    field_expr
  end
end

#inline_loop_element_type(element) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 263

def inline_loop_element_type(element)
  if element.is_a?(Types::FieldHandle)
    @ctx.types.fetch("field_handle")
  elsif element.is_a?(Types::CallableHandle)
    @ctx.types.fetch("callable_handle")
  elsif element.is_a?(Types::AttributeHandle)
    @ctx.types.fetch("attribute_handle")
  elsif element.is_a?(Types::MemberHandle)
    @ctx.types.fetch("member_handle")
  elsif element.is_a?(Types::StructHandle)
    @ctx.types.fetch("struct_handle")
  else
    @ctx.types.fetch("int")
  end
end

#lower_block(statements, env:, active_defers:, return_type:, loop_flow:, allow_return: true) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 14

def lower_block(statements, env:, active_defers:, return_type:, loop_flow:, allow_return: true)
  local_env = duplicate_env(env)
  lowered = []
  local_defers = []
  local_env[:return_context] = {
    return_type:,
    active_defers:,
    local_defers:,
    allow_return:,
  }

  statements.each do |statement|
    case statement
    when AST::DeferStmt
      local_defers << lower_defer_cleanup_body(statement.body, env: local_env, return_type:)
    when AST::UnsafeStmt
      lower_block_unsafe_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
    when AST::LocalDecl
      lower_block_local_decl_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
    when AST::Assignment
      lower_block_assignment_stmt(statement, lowered:, local_defers:, local_env:)
    when AST::IfStmt
      lower_block_if_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
    when AST::MatchStmt
      lower_block_match_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
    when AST::StaticAssert
      lowered << lower_static_assert(statement, env: local_env)
    when AST::ForStmt
      if statement.inline
        lowered.concat(lower_inline_for_stmt(statement, env: local_env, active_defers:, return_type:, allow_return:))
      else
        lowered << lower_for_stmt(statement, env: local_env, active_defers: active_defers + local_defers, return_type:, allow_return:)
      end
    when AST::ParallelBlockStmt
      lowered << lower_parallel_block_stmt(statement, env: local_env, active_defers: active_defers + local_defers)
    when AST::GatherStmt
      lowered << lower_gather_stmt(statement, env: local_env)
    when AST::WhileStmt
      if statement.inline
        lowered.concat(lower_inline_while_stmt(statement, env: local_env, active_defers:, return_type:, allow_return:))
      else
        lowered << lower_while_stmt(statement, env: local_env, active_defers: active_defers + local_defers, return_type:, allow_return:)
      end
    when AST::PassStmt
      nil
    when AST::BreakStmt
      raise LoweringError.new("break must be inside a loop",
        line: statement.line, column: statement.column, path: @ctx.current_analysis_path) unless loop_flow

      lowered.concat(lower_loop_exit(loop_flow[:break_target], local_defers, loop_flow[:break_defers]))
    when AST::ContinueStmt
      raise LoweringError.new("continue must be inside a loop",
        line: statement.line, column: statement.column, path: @ctx.current_analysis_path) unless loop_flow

      lowered.concat(lower_loop_exit(loop_flow[:continue_target], local_defers, loop_flow[:continue_defers]))
    when AST::ReturnStmt
      lower_block_return_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, allow_return:)
    when AST::ExpressionStmt
      lower_block_expression_stmt(statement, lowered:, local_defers:, local_env:)
    when AST::EmitStmt
      lowered.concat(lower_emit_stmt(statement, env: local_env))
    when AST::WhenStmt
      lower_block_when_stmt(statement, lowered:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
    else
      raise LoweringError.new("unsupported statement #{statement.class.name}",
        line: statement.line, column: statement.column, path: @ctx.current_analysis_path)
    end
  end

  unless terminating_ir_statement?(lowered.last)
    lowered.concat(cleanup_statements(local_defers, []))
  end
  lowered
end

#lower_block_assignment_stmt(statement, lowered:, local_defers:, local_env:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 509

def lower_block_assignment_stmt(statement, lowered:, local_defers:, local_env:)
  if statement.operator == "=" &&
     statement.target.is_a?(AST::IndexAccess) &&
     statement.target.index.is_a?(AST::RangeExpr) &&
     statement.value.is_a?(AST::ExpressionList)
    lowered.concat(lower_range_index_assignment(statement, env: local_env))
    return
  end
  target = lower_assignment_target(statement.target, env: local_env)
  prepared_cleanups = []
  prepared_setup, prepared_value, prepared_cleanups = prepare_expression_with_cleanups(
    statement.value,
    env: local_env,
    expected_type: target.type,
    allow_root_statement_foreign: true,
    materialize_array_calls: !array_type?(target.type),
  )
  lowered.concat(prepared_setup)
  if (foreign_call = foreign_call_info(prepared_value, local_env))
    setup, value, call_type, release_assignments, cleanup_statements = lower_foreign_call_components(
      foreign_call,
      env: local_env,
      expected_type: target.type,
      statement_position: false,
    )
    lowered.concat(setup)
    raise LoweringError.new("foreign call used in assignment must return a value",
      line: statement.line, column: statement.column, path: @ctx.current_analysis_path) if call_type == @ctx.types.fetch("void")
    raise LoweringError.new("consuming foreign calls must return void",
      line: statement.line, column: statement.column, 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, local_env)
    local_defers.concat(suppress_format_releases_for_assignment(prepared_cleanups, target.type))
    return
  else
    value = if statement.operator == "="
      lower_contextual_expression(
        prepared_value,
        env: local_env,
        expected_type: target.type,
        external_numeric: external_numeric_assignment_target?(statement.target, env: local_env),
        contextual_int_to_float: contextual_int_to_float_target?(target.type),
      )
    elsif ["+=", "-=", "*=", "/="].include?(statement.operator)
      lower_contextual_expression(
        prepared_value,
        env: local_env,
        expected_type: target.type,
        contextual_int_to_float: contextual_int_to_float_target?(target.type),
      )
    else
      lower_expression(prepared_value, env: local_env, expected_type: target.type)
    end
  end
  if target.type.is_a?(Types::Nullable) && value && !value.type.is_a?(Types::Nullable) && !pointer_like_type?(target.type.base)
    value = nullable_some_literal(target.type, value)
  end
  update_cstr_metadata_for_assignment!(statement, prepared_value, local_env)
  local_defers.concat(suppress_format_releases_for_assignment(prepared_cleanups, target.type))
  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(local_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
end

#lower_block_expression_stmt(statement, lowered:, local_defers:, local_env:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 422

def lower_block_expression_stmt(statement, lowered:, local_defers:, local_env:)
  if (format_sink_statements = lower_explicit_format_sink_expression_statement(statement.expression, env: local_env, line: statement.line))
    lowered.concat(format_sink_statements)
    return
  end

  expression_expected_type = if statement.expression.is_a?(AST::UnaryOp) && statement.expression.operator == "?"
    nil
  else
    infer_expression_type(statement.expression, env: local_env)
  end
  prepared_setup, prepared_expression, prepared_cleanups = prepare_expression_with_cleanups(
    statement.expression,
    env: local_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, local_env))
    setup, _value = lower_foreign_call_statement(
      foreign_call,
      env: local_env,
      expected_type: foreign_call[:binding].type.return_type,
      statement_position: true,
      discard_result: true,
    )
    lowered.concat(setup)
    lowered.concat(prepared_cleanups.flat_map(&:itself))
    local_env[:scopes] = scopes_with_refinements(local_env[:scopes], consuming_foreign_call_refinements(foreign_call, local_env))
  elsif prepared_expression
    lowered << IR::ExpressionStmt.new(expression: lower_expression(prepared_expression, env: local_env), line: statement.line, path: @ctx.current_analysis_path)
    lowered.concat(prepared_cleanups.flat_map(&:itself))
  else
    lowered.concat(prepared_cleanups.flat_map(&:itself))
  end
end

#lower_block_if_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 590

def lower_block_if_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
  if statement.inline
    lowered.concat(lower_inline_if_stmt(statement, env: local_env, active_defers:, return_type:, allow_return:))
    return
  end

  false_refinements = {}
  branch_entries = []

  unless statement.branches.empty?
    if @bypass_sema_type_cache
      ct_cond = compile_time_const_value(statement.branches.first.condition, env: local_env)
      if ct_cond == true
        lowered.concat(lower_block(
          statement.branches.first.body,
          env: local_env,
          active_defers: active_defers + local_defers,
          return_type:,
          loop_flow: nested_loop_flow(loop_flow, local_defers),
          allow_return:,
        ))
        return
      elsif ct_cond == false
        if statement.else_body
          lowered.concat(lower_block(
            statement.else_body,
            env: local_env,
            active_defers: active_defers + local_defers,
            return_type:,
            loop_flow: nested_loop_flow(loop_flow, local_defers),
            allow_return:,
          ))
        end
        return
      end
    end
  end

  statement.branches.each do |branch|
    branch_env = env_with_refinements(local_env, false_refinements)
    condition_setup, prepared_condition, condition_cleanups = prepare_expression_with_cleanups(
      branch.condition,
      env: branch_env,
      expected_type: @ctx.types.fetch("bool"),
    )
    true_refinements = merge_refinements(false_refinements, flow_refinements(branch.condition, truthy: true, env: branch_env))

    branch_entries << [
      condition_setup,
      condition_cleanups,
      lower_expression(prepared_condition, env: branch_env, expected_type: @ctx.types.fetch("bool")),
      lower_block(
        branch.body,
        env: env_with_refinements(local_env, true_refinements),
        active_defers: active_defers + local_defers,
        return_type:,
        loop_flow: nested_loop_flow(loop_flow, local_defers),
        allow_return:,
      ),
    ]

    false_refinements = merge_refinements(false_refinements, flow_refinements(branch.condition, truthy: false, env: branch_env))
  end

  nested_else_body = statement.else_body ? lower_block(
    statement.else_body,
    env: env_with_refinements(local_env, false_refinements),
    active_defers: active_defers + local_defers,
    return_type:,
    loop_flow: nested_loop_flow(loop_flow, local_defers),
    allow_return:,
  ) : []

  nested_if = nested_else_body
  branch_entries.reverse_each do |condition_setup, condition_cleanups, condition, then_body|
    condition_cleanup_statements = condition_cleanups.flat_map(&:itself)
    nested_if = [
      *condition_setup,
      IR::IfStmt.new(
        condition:,
        then_body: condition_cleanup_statements + then_body,
        else_body: condition_cleanup_statements + nested_if,
      ),
    ]
  end
  lowered.concat(nested_if)

  merge_cstr_metadata_after_if_statement!(statement, local_env)

  if statement.else_body.nil? && statement.branches.all? { |branch| cfg_block_always_terminates?(branch.body) }
    local_env[:scopes] = scopes_with_refinements(local_env[:scopes], false_refinements)
  end
end

#lower_block_local_decl_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 684

def lower_block_local_decl_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
  if statement.destructure_bindings
    lower_destructure_decl(statement, env: local_env, lowered:, local_defers:, active_defers:, return_type:, loop_flow:, allow_return:)
    return
  end

  storage_type = if statement.else_body
    infer_expression_type(statement.value, env: local_env)
  elsif statement.type
    resolve_type_ref(statement.type)
  else
    infer_expression_type(statement.value, env: local_env)
  end
  type = if statement.else_body
    statement.type ? resolve_type_ref(statement.type) : let_else_success_type(storage_type)
  else
    storage_type
  end
  linkage_name = let_else_storage_c_name(statement, local_env)
  decl_name = bind_let_else_local?(statement) ? statement.name : linkage_name
  prepared_setup = []
  prepared_value = statement.value
  prepared_cleanups = []
  emitted_decl = false
  if statement.value
    local_env[:current_local_name] = linkage_name
    prepared_setup, prepared_value, prepared_cleanups = prepare_expression_with_cleanups(
      statement.value,
      env: local_env,
      expected_type: storage_type,
      allow_root_statement_foreign: true,
      materialize_array_calls: !array_type?(storage_type),
    )
    lowered.concat(prepared_setup)
  end
  if prepared_value && (foreign_call = foreign_call_info(prepared_value, local_env))
    setup, value, call_type, release_assignments, cleanup_statements = lower_foreign_call_components(
      foreign_call,
      env: local_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: statement.line, column: statement.column, path: @ctx.current_analysis_path) if call_type == @ctx.types.fetch("void")
    raise LoweringError.new("consuming foreign calls must return void",
      line: statement.line, column: statement.column, path: @ctx.current_analysis_path) unless release_assignments.empty?

    lowered << IR::LocalDecl.new(name: decl_name, linkage_name:, type: storage_type, value:, line: statement.line, path: @ctx.current_analysis_path)
    lowered.concat(cleanup_statements)
    emitted_decl = true
  elsif prepared_value.is_a?(AST::ProcExpr)
    setup, value = lower_proc_expression_for_local(prepared_value, env: local_env, local_name: statement.name, proc_type: storage_type)
    lowered.concat(setup)
  elsif prepared_value
    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
  if value && storage_type.is_a?(Types::Nullable) && !value.type.is_a?(Types::Nullable) && !pointer_like_type?(storage_type.base)
    value = nullable_some_literal(storage_type, value)
  end
  if bind_let_else_local?(statement)
    current_actual_scope(local_env[:scopes])[statement.name] = local_binding(
      type:,
      storage_type:,
      linkage_name:,
      mutable: statement.kind == :var,
      pointer: false,
      projection: statement.else_body ? let_else_binding_projection(storage_type) : nil,
      cstr_backed: cstr_backed_storage_value?(storage_type, prepared_value, local_env),
      cstr_list_backed: cstr_list_backed_storage_value?(storage_type, prepared_value, local_env),
      const_value: statement.else_body ? nil : statement.kind == :let && prepared_value ? compile_time_const_value(prepared_value, env: local_env) : nil,
    )
  end
  lowered << IR::LocalDecl.new(name: decl_name, linkage_name:, type: storage_type, value:, line: statement.line, path: @ctx.current_analysis_path) unless emitted_decl
  if statement.else_body
    else_env = if statement.else_binding
      duplicate_env(local_env).tap do |env_with_error|
        current_actual_scope(env_with_error[:scopes])[statement.else_binding.name] = local_binding(
          type: let_else_error_type(storage_type),
          storage_type:,
          linkage_name:,
          mutable: false,
          pointer: false,
          projection: :result_failure_error,
        )
      end
    else
      local_env
    end
    else_body = lower_block(
      statement.else_body,
      env: else_env,
      active_defers: active_defers + local_defers + prepared_cleanups,
      return_type:,
      loop_flow: nested_loop_flow(loop_flow, local_defers),
      allow_return:,
    )
    local_ref = IR::Name.new(name: linkage_name, type: storage_type, pointer: false)
    lowered << IR::IfStmt.new(
      condition: let_else_failure_condition(local_ref, storage_type),
      then_body: else_body,
      else_body: nil,
    )
  end
  local_defers.concat(prepared_cleanups)
  if contains_proc_storage_type?(storage_type)
    local_value = IR::Name.new(name: linkage_name, type: storage_type, pointer: false)
    local_defers << lower_proc_contained_guarded_release_statements(local_value, storage_type)
    if statement.value && !expression_contains_proc_expr?(statement.value)
      lowered.concat(lower_proc_contained_retain_statements(local_value, storage_type))
    end
  end
end

#lower_block_match_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 805

def lower_block_match_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
  if statement.inline
    lowered.concat(lower_inline_match_stmt(statement, env: local_env, active_defers:, return_type:, allow_return:))
    return
  end
  scrutinee_type = infer_expression_type(statement.expression, env: local_env)
  expression_setup, prepared_expression, expression_cleanups = prepare_expression_with_cleanups(
    statement.expression,
    env: local_env,
    expected_type: scrutinee_type,
  )
  lowered.concat(expression_setup)
  expression = lower_expression(prepared_expression, env: local_env, expected_type: scrutinee_type)

  if scrutinee_type.is_a?(Types::Variant) &&
     statement.arms.any? { |arm| arm.binding_name && !wildcard_arm_pattern?(arm.pattern) } &&
     !duplicable_foreign_argument_expression?(expression)
    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: expression)
    expression = IR::Name.new(name: scrutinee_linkage_name, type: scrutinee_type, pointer: false)
  end

  if scrutinee_type.is_a?(Types::Variant)
    if statement.arms.any? { |arm| arm.pattern.is_a?(AST::Call) }
      lower_block_variant_struct_pattern_match(statement, scrutinee_type:, expression:, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
    else
      kind_type = @ctx.types.fetch("int")
      kind_expr = IR::Member.new(receiver: expression, member: "kind", type: kind_type)
      arm_loop_flow = switch_loop_flow(loop_flow, local_defers)
      cases = statement.arms.map do |arm|
        arm_local_env = duplicate_env(local_env)
        binding_decl = 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)
            data_expr = IR::Member.new(receiver: expression, 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_local_env[:scopes].last[arm.binding_name] = local_binding(type: payload_type, linkage_name: binding_c, mutable: true, pointer: false)
            IR::LocalDecl.new(name: arm.binding_name, linkage_name: binding_c, type: payload_type, value: arm_expr)
          end
        end
        body = lower_block(
          arm.body,
          env: arm_local_env,
          active_defers: active_defers + local_defers,
          return_type:,
          loop_flow: arm_loop_flow,
          allow_return:,
        )
        body = [binding_decl, *body].compact if binding_decl
        if wildcard_arm_pattern?(arm.pattern)
          IR::SwitchDefaultCase.new(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:)
        end
      end
      lowered << IR::SwitchStmt.new(expression: kind_expr, cases:, exhaustive: true)
    end
  elsif scrutinee_type.is_a?(Types::StringView)
    lower_block_string_match_stmt(statement, scrutinee_type:, expression:, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
  elsif scrutinee_type.is_a?(Types::Tuple)
    lower_block_tuple_match_stmt(statement, scrutinee_type:, expression:, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
  else
    has_range_arms = statement.arms.any? { |arm| arm.pattern.is_a?(AST::RangeExpr) }

    if has_range_arms
      lower_block_range_match_stmt(statement, scrutinee_type:, expression:, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
    else
      arm_loop_flow = switch_loop_flow(loop_flow, local_defers)
      cases = statement.arms.map do |arm|
        body = lower_block(
          arm.body,
          env: local_env,
          active_defers: active_defers + local_defers,
          return_type:,
          loop_flow: arm_loop_flow,
          allow_return:,
        )
        if wildcard_arm_pattern?(arm.pattern)
          IR::SwitchDefaultCase.new(body:)
        else
          value = lower_expression(arm.pattern, env: local_env, expected_type: scrutinee_type)
          IR::SwitchCase.new(value:, body:)
        end
      end
      lowered << IR::SwitchStmt.new(expression:, cases:, exhaustive: true)
    end
  end
  lowered.concat(expression_cleanups.flat_map(&:itself))
end

#lower_block_range_match_stmt(statement, scrutinee_type:, expression:, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 1119

def lower_block_range_match_stmt(statement, scrutinee_type:, expression:, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
  arm_loop_flow = switch_loop_flow(loop_flow, local_defers)
  bool_type = @ctx.types.fetch("bool")
  non_wildcard = statement.arms.reject { |arm| wildcard_arm_pattern?(arm.pattern) }
  wildcard = statement.arms.find { |arm| wildcard_arm_pattern?(arm.pattern) }
  else_body = if wildcard
    lower_block(wildcard.body, env: local_env, active_defers: active_defers + local_defers, return_type:, loop_flow: arm_loop_flow, allow_return:)
  else
    []
  end
  non_wildcard.reverse_each do |arm|
    arm_body = lower_block(
      arm.body,
      env: local_env,
      active_defers: active_defers + local_defers,
      return_type:,
      loop_flow: arm_loop_flow,
      allow_return:,
    )
    cond = if arm.pattern.is_a?(AST::RangeExpr)
      lower_range_match_condition(arm.pattern, expression, bool_type, env: local_env)
    else
      lit = lower_expression(arm.pattern, env: local_env, expected_type: scrutinee_type)
      IR::Binary.new(operator: "==", left: expression, right: lit, type: bool_type)
    end
    else_body = [IR::IfStmt.new(condition: cond, then_body: arm_body, else_body:)]
  end
  lowered.concat(else_body)
end

#lower_block_return_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, allow_return:) ⇒ Object

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# File 'lib/milk_tea/core/lowering/block.rb', line 460

def lower_block_return_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, allow_return:)
  raise LoweringError.new("return is not allowed inside defer blocks",
    line: statement.line, column: statement.column, path: @ctx.current_analysis_path) unless allow_return

  value = nil
  prepared_setup = []
  prepared_value = statement.value
  prepared_cleanups = []
  if statement.value
    prepared_setup, prepared_value, prepared_cleanups = prepare_expression_with_cleanups(
      statement.value,
      env: local_env,
      expected_type: return_type,
      allow_root_statement_foreign: true,
      materialize_array_calls: !array_type?(return_type),
    )
    lowered.concat(prepared_setup)
  end
  if prepared_value && (foreign_call = foreign_call_info(prepared_value, local_env))
    setup, value = lower_foreign_call_statement(foreign_call, env: local_env, expected_type: return_type, statement_position: false)
    lowered.concat(setup)
  end
  value ||= prepared_value ? lower_contextual_expression(
    prepared_value,
    env: local_env,
    expected_type: return_type,
    contextual_int_to_float: contextual_int_to_float_target?(return_type),
  ) : nil
  if prepared_cleanups.any? && cstr_trackable_type?(return_type)
    raise LoweringError.new("formatted string temporaries cannot be returned as borrowed text; use std.fmt.format(f\"...\") when ownership must escape",
      line: statement.line, column: statement.column, path: @ctx.current_analysis_path)
  end

  prepared_cleanup_list = prepared_cleanups.flat_map(&:itself)
  if prepared_cleanup_list.any? && return_type.is_a?(Types::Struct) && struct_contains_string_field?(return_type)
    prepared_cleanup_list = prepared_cleanup_list.reject { |stmt| stmt.is_a?(IR::ExpressionStmt) && stmt.expression.is_a?(IR::Call) && stmt.expression.callee == "mt_format_str_release" }
  end
  cleanup = prepared_cleanup_list + cleanup_statements(local_defers, active_defers)
  needs_proc_retain = value && contains_proc_storage_type?(return_type) && !local_defers.empty? && !expression_contains_proc_expr?(prepared_value)
  if value && (!cleanup.empty? && !cleanup_safe_return_expression?(prepared_value) || needs_proc_retain)
    return_value_name = fresh_c_temp_name(local_env, "return_value")
    lowered << IR::LocalDecl.new(name: return_value_name, linkage_name: return_value_name, type: return_type, value:)
    value = IR::Name.new(name: return_value_name, type: return_type, pointer: false)
  end
  lowered.concat(lower_proc_contained_retain_statements(value, return_type)) if needs_proc_retain
  lowered.concat(cleanup)
  lowered << IR::ReturnStmt.new(value:, line: statement.line, path: @ctx.current_analysis_path)
end

#lower_block_string_match_stmt(statement, scrutinee_type:, expression:, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 1054

def lower_block_string_match_stmt(statement, scrutinee_type:, expression:, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
  arm_loop_flow = switch_loop_flow(loop_flow, local_defers)
  bool_type = @ctx.types.fetch("bool")
  non_wildcard = statement.arms.reject { |arm| wildcard_arm_pattern?(arm.pattern) }
  wildcard = statement.arms.find { |arm| wildcard_arm_pattern?(arm.pattern) }
  else_body = if wildcard
    lower_block(
      wildcard.body,
      env: local_env,
      active_defers: active_defers + local_defers,
      return_type:,
      loop_flow: arm_loop_flow,
      allow_return:,
    )
  else
    []
  end
  non_wildcard.reverse_each do |arm|
    arm_body = lower_block(
      arm.body,
      env: local_env,
      active_defers: active_defers + local_defers,
      return_type:,
      loop_flow: arm_loop_flow,
      allow_return:,
    )
    lit = lower_expression(arm.pattern, env: local_env, expected_type: scrutinee_type)
    cond = IR::Binary.new(operator: "==", left: expression, right: lit, type: bool_type)
    else_body = [IR::IfStmt.new(condition: cond, then_body: arm_body, else_body:)]
  end
  lowered.concat(else_body)
end

#lower_block_tuple_match_stmt(statement, scrutinee_type:, expression:, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 1087

def lower_block_tuple_match_stmt(statement, scrutinee_type:, expression:, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
  arm_loop_flow = switch_loop_flow(loop_flow, local_defers)
  bool_type = @ctx.types.fetch("bool")
  non_wildcard = statement.arms.reject { |arm| wildcard_arm_pattern?(arm.pattern) }
  wildcard = statement.arms.find { |arm| wildcard_arm_pattern?(arm.pattern) }
  else_body = if wildcard
    lower_block(
      wildcard.body,
      env: local_env,
      active_defers: active_defers + local_defers,
      return_type:,
      loop_flow: arm_loop_flow,
      allow_return:,
    )
  else
    []
  end
  non_wildcard.reverse_each do |arm|
    arm_body = lower_block(
      arm.body,
      env: local_env,
      active_defers: active_defers + local_defers,
      return_type:,
      loop_flow: arm_loop_flow,
      allow_return:,
    )
    cond = tuple_arm_condition(arm, expression, scrutinee_type, bool_type, env: local_env)
    else_body = [IR::IfStmt.new(condition: cond, then_body: arm_body, else_body:)]
  end
  lowered.concat(else_body)
end

#lower_block_unsafe_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 383

def lower_block_unsafe_stmt(statement, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
  body = lower_block(
    statement.body,
    env: local_env,
    active_defers: active_defers + local_defers,
    return_type:,
    loop_flow: nested_loop_flow(loop_flow, local_defers),
    allow_return:,
  )
  lowered << IR::BlockStmt.new(body:)
end

#lower_block_variant_struct_pattern_match(statement, scrutinee_type:, expression:, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 899

def lower_block_variant_struct_pattern_match(statement, scrutinee_type:, expression:, lowered:, local_defers:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
  kind_type = @ctx.types.fetch("int")
  arm_loop_flow = switch_loop_flow(loop_flow, local_defers)
  @match_label_counter ||= 0
  @match_label_counter += 1
  m = @match_label_counter
  match_end_label = "__mt_match_#{m}_end"
  arm_next_label = "__mt_match_#{m}_arm_next"

  statement.arms.each_with_index do |arm, arm_index|
    arm_local_env = duplicate_env(local_env)
    arm_name = variant_match_arm_name_from_pattern(arm.pattern) unless wildcard_arm_pattern?(arm.pattern)

    if arm_index > 0
      lowered << IR::LabelStmt.new(name: "__mt_match_#{m}_arm_#{arm_index}")
    end

    if arm_name && !wildcard_arm_pattern?(arm.pattern)
      tag_value = IR::Name.new(name: enum_member_c_name(scrutinee_type, "kind_#{arm_name}"), type: kind_type, pointer: false)
      tag_expr = IR::Member.new(receiver: expression, member: "kind", type: kind_type)
      goto_label = if arm_index < statement.arms.length - 1
        "__mt_match_#{m}_arm_#{arm_index + 1}"
      else
        arm_next_label
      end
      tag_check = IR::Binary.new(operator: "!=", left: tag_expr, right: tag_value, type: @ctx.types.fetch("bool"))
      lowered << IR::IfStmt.new(condition: tag_check, then_body: [IR::GotoStmt.new(label: goto_label)], else_body: [])
    end

    if arm_name && !wildcard_arm_pattern?(arm.pattern) && scrutinee_type.has_payload?(arm_name)
      fields = scrutinee_type.arm(arm_name)
      payload_type = Types::VariantArmPayload.new(scrutinee_type, arm_name, fields)
      data_expr = IR::Member.new(receiver: expression, member: "data", type: nil)
      arm_expr = IR::Member.new(receiver: data_expr, member: arm_name, type: payload_type)
      payload_c_name = fresh_c_temp_name(arm_local_env, "match_payload")
      arm_local_env[:scopes].last["__mt_payload"] = local_binding(type: payload_type, linkage_name: payload_c_name, mutable: true, pointer: false)

      arm_body_ir = []
      arm_body_ir << IR::LocalDecl.new(name: payload_c_name, linkage_name: payload_c_name, type: payload_type, value: arm_expr)

      nested_struct_fields = nil
      nested_struct_c_name = nil
      nested_struct_type = nil
      if fields.size == 1 && fields.values.first.is_a?(Types::Struct)
        native_field = fields.keys.first
        has_native_reference = arm.pattern.arguments.any? do |arg|
          next false if !arg.name && arg.value.is_a?(AST::Identifier) && arg.value.name == "_"

          name = arg.name || (arg.value.is_a?(AST::Identifier) ? arg.value.name : nil)
          name == native_field
        end
        unless has_native_reference
          nested_struct_type = fields.values.first
          nested_struct_fields = nested_struct_type.fields
          single_field_name = fields.keys.first
          nested_struct_c_name = fresh_c_temp_name(arm_local_env, "match_struct")
          struct_expr = IR::Member.new(
            receiver: IR::Name.new(name: payload_c_name, type: payload_type, pointer: false),
            member: single_field_name,
            type: nested_struct_type,
          )
          arm_body_ir << IR::LocalDecl.new(name: nested_struct_c_name, linkage_name: nested_struct_c_name, type: nested_struct_type, value: struct_expr)
        end
      end

      if arm.pattern.is_a?(AST::Call) && !arm.pattern.arguments.empty?
        pattern_fields = nested_struct_fields || fields
        pattern_receiver_name = nested_struct_c_name || payload_c_name
        pattern_receiver_type = nested_struct_type || payload_type

        arm.pattern.arguments.each do |arg|
          if !arg.name && arg.value.is_a?(AST::BinaryOp) && arg.value.left.is_a?(AST::Identifier)
            field_name = arg.value.left.name
            next unless pattern_fields.key?(field_name)

            field_type = pattern_fields[field_name]
            field_expr = IR::Member.new(receiver: IR::Name.new(name: pattern_receiver_name, type: pattern_receiver_type, pointer: false), member: field_name, type: field_type)
            field_expr = dereference_if_self_ref(field_expr, field_type, scrutinee_type)
            rhs_expr = lower_expression(arg.value.right, env: arm_local_env, expected_type: field_type)
            guard_condition = IR::Binary.new(operator: arg.value.operator, left: field_expr, right: rhs_expr, type: @ctx.types.fetch("bool"))
            arm_body_ir << IR::IfStmt.new(condition: guard_condition, then_body: [], else_body: [IR::GotoStmt.new(label: goto_label)])
          end

          if arg.name
            field_name = arg.name
            next unless pattern_fields.key?(field_name)

            field_type = pattern_fields[field_name]
            field_expr = IR::Member.new(receiver: IR::Name.new(name: pattern_receiver_name, type: pattern_receiver_type, pointer: false), member: field_name, type: field_type)
            field_expr = dereference_if_self_ref(field_expr, field_type, scrutinee_type)
            value_expr = lower_expression(arg.value, env: arm_local_env, expected_type: field_type)
            eq_check = IR::Binary.new(operator: "!=", left: field_expr, right: value_expr, type: @ctx.types.fetch("bool"))
            arm_body_ir << IR::IfStmt.new(condition: eq_check, then_body: [IR::GotoStmt.new(label: goto_label)], else_body: [])
          end
        end

        arm.pattern.arguments.each do |arg|
          next if arg.name
          next unless arg.value.is_a?(AST::Identifier)
          next if arg.value.name == "_"

          field_name = arg.value.name
          next unless pattern_fields.key?(field_name)

          field_type = pattern_fields[field_name]
          binding_c = c_local_name(field_name)
          field_expr = IR::Member.new(receiver: IR::Name.new(name: pattern_receiver_name, type: pattern_receiver_type, pointer: false), member: field_name, type: field_type)
          field_expr = dereference_if_self_ref(field_expr, field_type, scrutinee_type)
          arm_body_ir << IR::LocalDecl.new(name: binding_c, linkage_name: binding_c, type: field_type, value: field_expr)
          arm_local_env[:scopes].last[field_name] = local_binding(type: field_type, linkage_name: binding_c, mutable: false, pointer: false)
        end
      end

      if arm.binding_name && !wildcard_arm_pattern?(arm.pattern)
        binding_c = c_local_name(arm.binding_name)
        if arm_name && scrutinee_type.has_payload?(arm_name)
          payload_key = "__mt_payload"
          if arm_local_env[:scopes].last.key?(payload_key)
            payload_binding = arm_local_env[:scopes].last[payload_key]
            arm_local_env[:scopes].last[arm.binding_name] = local_binding(type: payload_binding[:type], linkage_name: binding_c, mutable: true, pointer: false)
            payload_ref = IR::Name.new(name: payload_binding[:linkage_name], type: payload_binding[:type], pointer: false)
            arm_body_ir << IR::LocalDecl.new(name: arm.binding_name, linkage_name: binding_c, type: payload_binding[:type], value: payload_ref)
          end
        end
      end

      body = lower_block(
        arm.body,
        env: arm_local_env,
        active_defers: active_defers + local_defers,
        return_type:,
        loop_flow: arm_loop_flow,
        allow_return:,
      )
      arm_body_ir.concat(body)
      arm_body_ir << IR::GotoStmt.new(label: match_end_label)

      lowered << IR::BlockStmt.new(body: arm_body_ir)
    else
      body = lower_block(
        arm.body,
        env: arm_local_env,
        active_defers: active_defers + local_defers,
        return_type:,
        loop_flow: arm_loop_flow,
        allow_return:,
      )
      lowered << IR::BlockStmt.new(body: body + [IR::GotoStmt.new(label: match_end_label)])
    end
  end

  lowered << IR::LabelStmt.new(name: arm_next_label)
  lowered << IR::LabelStmt.new(name: match_end_label)
end

#lower_block_when_stmt(statement, lowered:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 395

def lower_block_when_stmt(statement, lowered:, local_env:, active_defers:, return_type:, loop_flow:, allow_return:)
  discriminant = compile_time_const_value(statement.discriminant)
  chosen_branch = statement.branches.find do |branch|
    discriminant == compile_time_const_value(branch.pattern)
  end

  if chosen_branch
    lowered.concat(lower_block(
      chosen_branch.body,
      env: local_env,
      active_defers:,
      return_type:,
      loop_flow:,
      allow_return:,
    ))
  elsif statement.else_body
    lowered.concat(lower_block(
      statement.else_body,
      env: local_env,
      active_defers:,
      return_type:,
      loop_flow:,
      allow_return:,
    ))
  end
end

#lower_destructure_decl(statement, env:, lowered:, local_defers:, active_defers:, return_type:, loop_flow:, allow_return:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 325

def lower_destructure_decl(statement, env:, lowered:, local_defers:, active_defers:, return_type:, loop_flow:, allow_return:)
  value_type = infer_expression_type(statement.value, env:)
  setup, prepared_value, _cleanups = prepare_expression_with_cleanups(statement.value, env:, expected_type: value_type)
  lowered.concat(setup)
  value = lower_contextual_expression(prepared_value, env:, expected_type: value_type)

  temp_name = fresh_c_temp_name(env, "destructure_val")
  lowered << IR::LocalDecl.new(name: temp_name, linkage_name: temp_name, type: value_type, value:)

  if statement.destructure_type_name
    # Struct destructure: find fields by name in the struct type
    destructure_type = value_type
    fields = destructure_type.fields
    statement.destructure_bindings.each do |name|
      next if name == "_"
      field_type = fields[name]
      field_expr = IR::Member.new(receiver: IR::Name.new(name: temp_name, type: destructure_type, pointer: false), member: name, type: field_type)
      decl_c_name = c_local_name(name)
      lowered << IR::LocalDecl.new(name: decl_c_name, linkage_name: decl_c_name, type: field_type, value: field_expr)
      env[:scopes].last[name] = local_binding(type: field_type, linkage_name: decl_c_name, mutable: false, pointer: false)
    end
  else
    # Tuple destructure: index by position
    statement.destructure_bindings.each_with_index do |name, index|
      next if name == "_"
      field_name = value_type.field_names[index]
      field_type = value_type.element_types[index]
      field_expr = IR::Member.new(receiver: IR::Name.new(name: temp_name, type: value_type, pointer: false), member: field_name, type: field_type)
      decl_c_name = c_local_name(name)
      lowered << IR::LocalDecl.new(name: decl_c_name, linkage_name: decl_c_name, type: field_type, value: field_expr)
      env[:scopes].last[name] = local_binding(type: field_type, linkage_name: decl_c_name, mutable: false, pointer: false)
    end
  end
end

#lower_emit_stmt(statement, env:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 279

def lower_emit_stmt(statement, env:)
  decl = statement.declaration
  case decl
  when AST::FunctionDef
    lower_emitted_function(decl, env:)
  when AST::StructDecl
    lower_emitted_struct(decl)
  when AST::ConstDecl
    lower_emitted_const(decl, env:)
  else
    raise LoweringError.new("emit is not supported for #{decl.class.name}",
      line: statement.line, column: statement.column, path: @ctx.current_analysis_path)
  end
end

#lower_emitted_const(decl, env:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 360

def lower_emitted_const(decl, env:)
  value = lower_static_storage_initializer(decl.value, env:, expected_type: decl.type ? resolve_type_ref(decl.type) : nil)
  type = decl.type ? resolve_type_ref(decl.type) : infer_expression_type(decl.value, env:)
  linkage_name = value_c_name(decl.name)
  constant = IR::Constant.new(name: decl.name, linkage_name:, type:, value:, line: decl.line, path: @ctx.current_analysis_path)
  @artifacts.emitted_declarations << constant
  []
end

#lower_emitted_function(decl, env:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 294

def lower_emitted_function(decl, env:)
  params = []
  param_setup = []
  return_type = decl.return_type ? resolve_type_ref(decl.return_type) : @ctx.types.fetch("void")
  linkage_name = "#{@ctx.module_prefix}#{decl.name}"

  decl.params.each do |param|
    param_type = param.type ? resolve_type_ref(param.type) : @ctx.types.fetch("int")
    param_linkage_name = c_local_name(param.name)
    params << IR::Param.new(name: param.name, linkage_name: param_linkage_name, type: param_type, pointer: false)
    env[:scopes].last[param.name] = local_binding(type: param_type, linkage_name: param_linkage_name, mutable: false, pointer: false)
  end

  body = lower_block(decl.body, env:, active_defers: [], return_type:, loop_flow: nil, allow_return: true)
  body = param_setup + body
  func = IR::Function.new(name: decl.name, linkage_name:, params:, return_type:, body:, entry_point: false, method_receiver_param: false)
  @artifacts.emitted_declarations << func
  []
end

#lower_emitted_struct(decl) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 314

def lower_emitted_struct(decl)
  fields = decl.fields.map do |field|
    field_type = field.type ? resolve_type_ref(field.type) : @ctx.types.fetch("int")
    IR::Field.new(name: field.name, type: field_type)
  end
  linkage_name = "#{@ctx.module_prefix}#{decl.name}"
  struct_decl = IR::StructDecl.new(name: decl.name, linkage_name:, fields:, packed: decl.respond_to?(:packed) ? decl.packed : false, alignment: nil)
  @artifacts.emitted_declarations << struct_decl
  []
end

#lower_inline_for_stmt(statement, env:, active_defers:, return_type:, allow_return:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 172

def lower_inline_for_stmt(statement, env:, active_defers:, return_type:, allow_return:)
  iterable = compile_time_const_value(statement.iterables.first, env:)
  return [] unless iterable.is_a?(Array) && !iterable.empty?

  loop_var_name = statement.bindings.first.name
  loop_var_type = inline_loop_element_type(iterable.first)
  lowered = []

  iterable.each do |element|
    iter_env = duplicate_env(env)
    current_actual_scope(iter_env[:scopes])[loop_var_name] = local_binding(
      type: loop_var_type,
      linkage_name: c_local_name(loop_var_name),
      mutable: false,
      pointer: false,
      const_value: element,
    )
    emit_stmts, other_stmts = statement.body.partition { |s| s.is_a?(AST::EmitStmt) }
    emit_stmts.each do |emit_stmt|
      lowered.concat(lower_emit_stmt(emit_stmt, env: iter_env))
    rescue LoweringError
      # emit for compile-time-only constructs — skip
    end

    unless other_stmts.empty?
      saved_type_env = @type_resolution_env
      saved_bypass = @bypass_sema_type_cache
      # Each unrolled iteration may bind the loop var to a different value
      # (e.g. a field whose `.type` differs per field), so expression types
      # must be re-inferred per iteration instead of reusing the single
      # sema-cached type computed for the representative first element.
      @type_resolution_env = iter_env
      @bypass_sema_type_cache = true
      begin
        body = lower_block(other_stmts, env: iter_env, active_defers:, return_type:, loop_flow: nil, allow_return:)
      ensure
        @type_resolution_env = saved_type_env
        @bypass_sema_type_cache = saved_bypass
      end
      lowered << IR::BlockStmt.new(body:) unless body.empty?
    end
  end

  lowered
end

#lower_inline_if_stmt(statement, env:, active_defers:, return_type:, allow_return:) ⇒ Object 



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

def lower_inline_if_stmt(statement, env:, active_defers:, return_type:, allow_return:)
  chosen_branch = statement.branches.find do |branch|
    ct_value = compile_time_const_value(branch.condition, env:)
    ct_value == true
  end

  if chosen_branch
    lower_block(chosen_branch.body, env:, active_defers:, return_type:, loop_flow: nil, allow_return:)
  elsif statement.else_body
    lower_block(statement.else_body, env:, active_defers:, return_type:, loop_flow: nil, allow_return:)
  else
    []
  end
end

#lower_inline_match_stmt(statement, env:, active_defers:, return_type:, allow_return:) ⇒ Object 



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# File 'lib/milk_tea/core/lowering/block.rb', line 250

def lower_inline_match_stmt(statement, env:, active_defers:, return_type:, allow_return:)
  scrutinee = compile_time_const_value(statement.expression, env:)
  return [] unless scrutinee

  chosen_arm = statement.arms.find do |arm|
    scrutinee == compile_time_const_value(arm.pattern, env:)
  end

  return [] unless chosen_arm

  lower_block(chosen_arm.body, env:, active_defers:, return_type:, loop_flow: nil, allow_return:)
end

#lower_inline_while_stmt(statement, env:, active_defers:, return_type:, allow_return:) ⇒ Object 



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

def lower_inline_while_stmt(statement, env:, active_defers:, return_type:, allow_return:)
  condition = compile_time_const_value(statement.condition, env:)
  return [] unless condition

  iterations = 0
  max_iterations = 10_000
  lowered = []

  while compile_time_const_value(statement.condition, env:) && iterations < max_iterations
    body = lower_block(statement.body, env:, active_defers:, return_type:, loop_flow: nil, allow_return:)
    lowered << IR::BlockStmt.new(body:) unless body.empty?
    iterations += 1
  end

  lowered
end

#lower_proc_expression_for_local(expression, env:, local_name:, proc_type:) ⇒ Object 



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

def lower_proc_expression_for_local(expression, env:, local_name:, proc_type:)
  captures = proc_capture_entries(expression, env)
  captures.each do |capture|
    if ref_type?(capture[:type]) || contains_ref_type?(capture[:type])
      raise LoweringError.new("proc capture #{capture[:name]} cannot use ref types",
        line: expression.line, column: expression.column, path: @ctx.current_analysis_path)
    end
  end

  proc_id = fresh_proc_symbol
  invoke_c_name = "#{@ctx.module_prefix}__proc_#{proc_id}__invoke"
  release_linkage_name = "#{@ctx.module_prefix}__proc_#{proc_id}__release"
  retain_c_name = "#{@ctx.module_prefix}__proc_#{proc_id}__retain"
  env_struct_type = nil
  setup = []

  env_value = if captures.empty?
    IR::NullLiteral.new(type: proc_env_pointer_type)
  else
    env_struct_type = Types::Struct.new("#{@ctx.module_prefix}__proc_#{proc_id}__env").define_fields(
      { "__mt_ref_count" => @ctx.types.fetch("ptr_uint") }.merge(captures.each_with_object({}) { |capture, fields| fields[capture[:field_name]] = capture[:type] }),
    )
    @artifacts.synthetic_structs << IR::StructDecl.new(
      name: env_struct_type.name,
      linkage_name: env_struct_type.name,
      fields: [IR::Field.new(name: "__mt_ref_count", type: @ctx.types.fetch("ptr_uint")), *captures.map { |capture| IR::Field.new(name: capture[:field_name], type: capture[:type]) }],
      packed: false,
      alignment: nil,
    )

    env_pointer_type = pointer_to(env_struct_type)
    env_name = fresh_c_temp_name(env, "#{local_name}_env")
    raw_allocation = IR::Call.new(
      callee: "mt_async_alloc",
      arguments: [IR::SizeofExpr.new(target_type: env_struct_type, type: @ctx.types.fetch("ptr_uint"))],
      type: proc_env_pointer_type,
    )
    setup << IR::LocalDecl.new(
      name: env_name,
      linkage_name: env_name,
      type: env_pointer_type,
      value: IR::Cast.new(target_type: env_pointer_type, expression: raw_allocation, type: env_pointer_type),
    )
    env_pointer = IR::Name.new(name: env_name, type: env_pointer_type, pointer: false)
    setup << IR::Assignment.new(
      target: IR::Member.new(receiver: env_pointer, member: "__mt_ref_count", type: @ctx.types.fetch("ptr_uint")),
      operator: "=",
      value: IR::IntegerLiteral.new(value: 1, type: @ctx.types.fetch("ptr_uint")),
    )
    captures.each do |capture|
      setup << IR::Assignment.new(
        target: IR::Member.new(receiver: env_pointer, member: capture[:field_name], type: capture[:type]),
        operator: "=",
        value: lower_expression(AST::Identifier.new(name: capture[:name]), env:, expected_type: capture[:type]),
      )
    end
    captures.each do |capture|
      next unless contains_proc_storage_type?(capture[:type])

      member = IR::Member.new(receiver: env_pointer, member: capture[:field_name], type: capture[:type])
      setup.concat(lower_proc_contained_retain_statements(member, capture[:type]))
    end
    IR::Cast.new(target_type: proc_env_pointer_type, expression: env_pointer, type: proc_env_pointer_type)
  end

  @artifacts.synthetic_functions << build_proc_invoke_function(expression, proc_type, captures, env_struct_type, invoke_c_name)
  @artifacts.synthetic_functions << build_proc_release_function(release_linkage_name, env_struct_type)
  @artifacts.synthetic_functions << build_proc_retain_function(retain_c_name, env_struct_type)

  [
    setup,
    IR::AggregateLiteral.new(
      type: proc_type,
      fields: [
        IR::AggregateField.new(name: "env", value: env_value),
        IR::AggregateField.new(name: "invoke", value: IR::Name.new(name: invoke_c_name, type: proc_invoke_function_type(proc_type), pointer: false)),
        IR::AggregateField.new(name: "release", value: IR::Name.new(name: release_linkage_name, type: proc_release_function_type, pointer: false)),
        IR::AggregateField.new(name: "retain", value: IR::Name.new(name: retain_c_name, type: proc_retain_function_type, pointer: false)),
      ],
    ),
  ]
end

#variant_self_referencing_field?(field_type, scrutinee_type) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/lowering/block.rb', line 369

def variant_self_referencing_field?(field_type, scrutinee_type)
  return false unless field_type.is_a?(Types::Variant) || field_type.is_a?(Types::VariantInstance)
  return false unless scrutinee_type.is_a?(Types::Variant) || scrutinee_type.is_a?(Types::VariantInstance)
  field_type == scrutinee_type
end