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Allow incomplete return types in function declarations. (#3875)

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Move completeness check to the point where the function is defined or
first called. This means we also defer deciding whether the function has
a return slot until that point. Instead of storing a return slot per
function, store the location of the return storage, which may or may not
be used, and compute and store a separate flag saying whether to use it
at the point of first use or definition.

This is the final piece in supporting simple `Make` functions in classes
as a replacement for constructors.
This commit is contained in:
Richard Smith
2024-04-11 07:23:56 +00:00
committed by GitHub
parent 28ceb4dd4e
commit 1b335402d1
173 changed files with 980 additions and 615 deletions
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toolchain/check/handle_function.cpp
+17 -23
View File
@@ -79,26 +79,16 @@ static auto BuildFunctionDecl(Context& context,
auto decl_block_id = context.inst_block_stack().Pop();
auto return_type_id = SemIR::TypeId::Invalid;
auto return_slot_id = SemIR::InstId::Invalid;
if (auto [return_node, return_storage_id] =
auto return_storage_id = SemIR::InstId::Invalid;
auto return_slot = SemIR::Function::ReturnSlot::NotComputed;
if (auto [return_node, maybe_return_storage_id] =
context.node_stack().PopWithNodeIdIf<Parse::NodeKind::ReturnType>();
return_storage_id) {
return_type_id = context.insts().Get(*return_storage_id).type_id();
return_type_id = context.AsCompleteType(return_type_id, [&] {
CARBON_DIAGNOSTIC(IncompleteTypeInFunctionReturnType, Error,
"Function returns incomplete type `{0}`.",
SemIR::TypeId);
return context.emitter().Build(
return_node, IncompleteTypeInFunctionReturnType, return_type_id);
});
if (!SemIR::GetInitRepr(context.sem_ir(), return_type_id)
.has_return_slot()) {
// The function only has a return slot if it uses in-place initialization.
} else {
return_slot_id = *return_storage_id;
}
maybe_return_storage_id) {
return_type_id = context.insts().Get(*maybe_return_storage_id).type_id();
return_storage_id = *maybe_return_storage_id;
} else {
// If there's no return type, there's no return slot.
return_slot = SemIR::Function::ReturnSlot::Absent;
}
SemIR::InstBlockId param_refs_id =
@@ -144,8 +134,9 @@ static auto BuildFunctionDecl(Context& context,
.implicit_param_refs_id = implicit_param_refs_id,
.param_refs_id = param_refs_id,
.return_type_id = return_type_id,
.return_slot_id = return_slot_id,
.is_extern = is_extern};
.return_storage_id = return_storage_id,
.is_extern = is_extern,
.return_slot = return_slot};
if (is_definition) {
function_info.definition_id = function_info.decl_id;
}
@@ -201,9 +192,9 @@ static auto BuildFunctionDecl(Context& context,
// TODO: Update this once valid signatures for the entry point are decided.
if (!context.inst_blocks().Get(implicit_param_refs_id).empty() ||
!context.inst_blocks().Get(param_refs_id).empty() ||
(return_slot_id.is_valid() &&
(return_type_id.is_valid() &&
return_type_id !=
context.GetBuiltinType(SemIR::BuiltinKind::BoolType) &&
context.GetBuiltinType(SemIR::BuiltinKind::IntType) &&
return_type_id != context.GetTupleType({}))) {
CARBON_DIAGNOSTIC(InvalidMainRunSignature, Error,
"Invalid signature for `Main.Run` function. Expected "
@@ -236,6 +227,9 @@ static auto HandleFunctionDefinitionAfterSignature(
context.scope_stack().Push(decl_id);
context.AddCurrentCodeBlockToFunction();
// Check the return type is complete.
CheckFunctionReturnType(context, function.return_storage_id, function);
// Check the parameter types are complete.
for (auto param_id : llvm::concat<SemIR::InstId>(
context.inst_blocks().Get(function.implicit_param_refs_id),