carbon-lang/toolchain/check/handle_pattern_binding.cpp

// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#include "toolchain/check/context.h"
#include "toolchain/check/convert.h"
#include "toolchain/sem_ir/node.h"

namespace Carbon::Check {

auto HandleAddress(Context& context, Parse::Node parse_node) -> bool {
  return context.TODO(parse_node, "HandleAddress");
}

auto HandleGenericPatternBinding(Context& context, Parse::Node parse_node)
    -> bool {
  return context.TODO(parse_node, "GenericPatternBinding");
}

auto HandlePatternBinding(Context& context, Parse::Node parse_node) -> bool {
  auto [type_node, parsed_type_id] =
      context.node_stack().PopExpressionWithParseNode();
  auto type_node_copy = type_node;
  auto cast_type_id = ExpressionAsType(context, type_node, parsed_type_id);

  // Get the name.
  auto [name_node, name_id] =
      context.node_stack().PopWithParseNode<Parse::NodeKind::Name>();

  // Allocate a node of the appropriate kind, linked to the name for error
  // locations.
  switch (auto context_parse_node_kind = context.parse_tree().node_kind(
              context.node_stack().PeekParseNode())) {
    case Parse::NodeKind::VariableIntroducer: {
      // A `var` declaration at class scope introduces a field.
      auto enclosing_class_decl =
          context.GetCurrentScopeAs<SemIR::ClassDeclaration>();
      if (!context.TryToCompleteType(cast_type_id, [&] {
            CARBON_DIAGNOSTIC(IncompleteTypeInVarDeclaration, Error,
                              "{0} has incomplete type `{1}`.", llvm::StringRef,
                              std::string);
            return context.emitter().Build(
                type_node_copy, IncompleteTypeInVarDeclaration,
                enclosing_class_decl ? "Field" : "Variable",
                context.sem_ir().StringifyType(cast_type_id, true));
          })) {
        cast_type_id = SemIR::TypeId::Error;
      }
      SemIR::NodeId value_id = SemIR::NodeId::Invalid;
      SemIR::TypeId value_type_id = cast_type_id;
      if (enclosing_class_decl) {
        auto& class_info =
            context.classes().Get(enclosing_class_decl->class_id);
        auto field_type_node_id = context.AddNode(SemIR::UnboundFieldType{
            parse_node, context.GetBuiltinType(SemIR::BuiltinKind::TypeType),
            class_info.self_type_id, cast_type_id});
        value_type_id = context.CanonicalizeType(field_type_node_id);
        value_id =
            context.AddNode(SemIR::Field{parse_node, value_type_id, name_id});

        // Add a corresponding field to the object representation of the class.
        context.args_type_info_stack().AddNode(
            SemIR::StructTypeField{parse_node, name_id, cast_type_id});
      } else {
        value_id = context.AddNode(
            SemIR::VarStorage{name_node, value_type_id, name_id});
      }
      context.AddNodeAndPush(
          parse_node,
          SemIR::BindName{name_node, value_type_id, name_id, value_id});
      break;
    }

    case Parse::NodeKind::ParameterListStart:
      // Parameters can have incomplete types in a function declaration, but not
      // in a function definition. We don't know which kind we have here.
      context.AddNodeAndPush(
          parse_node, SemIR::Parameter{name_node, cast_type_id, name_id});
      // TODO: Create a `BindName` node.
      break;

    case Parse::NodeKind::LetIntroducer:
      if (!context.TryToCompleteType(cast_type_id, [&] {
            CARBON_DIAGNOSTIC(IncompleteTypeInLetDeclaration, Error,
                              "`let` binding has incomplete type `{0}`.",
                              std::string);
            return context.emitter().Build(
                type_node_copy, IncompleteTypeInLetDeclaration,
                context.sem_ir().StringifyType(cast_type_id, true));
          })) {
        cast_type_id = SemIR::TypeId::Error;
      }
      // Create the node, but don't add it to a block until after we've formed
      // its initializer.
      // TODO: For general pattern parsing, we'll need to create a block to hold
      // the `let` pattern before we see the initializer.
      context.node_stack().Push(
          parse_node,
          context.nodes().AddInNoBlock(SemIR::BindName{
              name_node, cast_type_id, name_id, SemIR::NodeId::Invalid}));
      break;

    default:
      CARBON_FATAL() << "Found a pattern binding in unexpected context "
                     << context_parse_node_kind;
  }
  return true;
}

auto HandleTemplate(Context& context, Parse::Node parse_node) -> bool {
  return context.TODO(parse_node, "HandleTemplate");
}

}  // namespace Carbon::Check