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Initial support for return forms (#6556)

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The main changes here are:
- Introducing `InitForm` and `RefForm` to represent initializing and
reference forms (the two return forms currently supported by the
parser).
- Introducing the `FormType` singleton inst to represent their type
(i.e. `Core.Form`).
- Emitting an inst representing a function's declared return form as
part of handling the function signature.

The return form inst is currently ignored. Subsequent PRs will expose it
in `SemIR::Function` and use it to determine the form of call
expressions.
This commit is contained in:
Geoff Romer
2026-01-07 00:54:18 +00:00
committed by GitHub
parent 444c18dfa3
commit 505b1c86b9
225 changed files with 4164 additions and 2583 deletions
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toolchain/check/handle_function.cpp
+39 -19
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@@ -53,10 +53,7 @@ auto HandleParseNode(Context& context, Parse::FunctionIntroducerId node_id)
}
auto HandleParseNode(Context& context, Parse::ReturnTypeId node_id) -> bool {
// Propagate the type expression.
auto [type_node_id, type_inst_id] = context.node_stack().PopExprWithNodeId();
auto as_type = ExprAsType(context, type_node_id, type_inst_id);
context.PushReturnTypeInstId(as_type.inst_id);
// If the previous node was `IdentifierNameBeforeParams`, then it would have
// caused these entries to be pushed to the pattern stacks. But it's possible
@@ -71,16 +68,40 @@ auto HandleParseNode(Context& context, Parse::ReturnTypeId node_id) -> bool {
FullPatternStack::Kind::ExplicitParamList);
}
auto pattern_type_id = GetPatternType(context, as_type.type_id);
auto return_slot_pattern_id = AddPatternInst<SemIR::ReturnSlotPattern>(
context, node_id,
{.type_id = pattern_type_id, .type_inst_id = as_type.inst_id});
auto param_pattern_id = AddPatternInst<SemIR::OutParamPattern>(
context, node_id,
{.type_id = pattern_type_id,
.subpattern_id = return_slot_pattern_id,
.index = context.full_pattern_stack().NextCallParamIndex()});
context.node_stack().Push(node_id, param_pattern_id);
// Propagate the type expression.
auto form_expr = ExprAsReturnForm(context, type_node_id, type_inst_id);
context.PushReturnForm(form_expr);
llvm::SmallVector<SemIR::InstId, 1> return_patterns;
auto form_inst = context.insts().Get(form_expr.form_inst_id);
CARBON_KIND_SWITCH(form_inst) {
case SemIR::RefForm::Kind: {
break;
}
case CARBON_KIND(SemIR::InitForm init_form): {
auto pattern_type_id = GetPatternType(context, form_expr.type_id);
auto return_slot_pattern_id = AddPatternInst<SemIR::ReturnSlotPattern>(
context, node_id,
{.type_id = pattern_type_id,
.type_inst_id = form_expr.type_component_id});
return_patterns.push_back(AddPatternInst(
context,
SemIR::LocIdAndInst::UncheckedLoc(
type_node_id,
SemIR::OutParamPattern{.type_id = pattern_type_id,
.subpattern_id = return_slot_pattern_id,
.index = init_form.index})));
break;
}
case SemIR::ErrorInst::Kind: {
break;
}
default:
CARBON_FATAL("unexpected inst kind: {0}", form_inst);
}
context.node_stack().Push(
node_id, context.inst_blocks().AddCanonical(return_patterns));
return true;
}
@@ -385,17 +406,16 @@ static auto BuildFunctionDecl(Context& context,
Parse::AnyFunctionDeclId node_id,
bool is_definition)
-> std::pair<SemIR::FunctionId, SemIR::InstId> {
llvm::SmallVector<SemIR::InstId> return_patterns;
auto return_patterns_id = SemIR::InstBlockId::None;
auto return_type_inst_id = SemIR::TypeInstId::None;
if (auto [return_node, maybe_return_slot_pattern_id] =
if (auto [return_node, maybe_return_patterns_id] =
context.node_stack().PopWithNodeIdIf<Parse::NodeKind::ReturnType>();
maybe_return_slot_pattern_id) {
return_patterns.push_back(*maybe_return_slot_pattern_id);
return_type_inst_id = context.PopReturnTypeInstId();
maybe_return_patterns_id) {
return_patterns_id = *maybe_return_patterns_id;
return_type_inst_id = context.PopReturnForm().type_component_id;
CARBON_CHECK(return_type_inst_id.has_value());
}
auto return_patterns_id = context.inst_blocks().Add(return_patterns);
auto name = PopNameComponent(context, return_patterns_id);
auto name_context = context.decl_name_stack().FinishName(name);