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Make StartImplDecl into a more explicit GetOrAddImpl (Refactor Impl construction 2/7) (#6466)

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The GetOrAddImpl operation looks for an existing `Impl` with a matching
declaration and returns its ImplId, or finished the construction of a
new `Impl`, adds it to the store and returns a fresh `ImplId`.

This makes the case of reusing an existing `Impl` into a short
early-out, demonstrating more clearly that we are reusing existing work,
and avoiding duplicate work such as checking for diagnostics that would
have already been checked in the previous (matching) declaration.

The `ExtendImpl` helper is renamed to be more explicit about its
behaviour, as `ApplyExtendImplAs`, and it constructs the data it needs
from the `Impl` and the `extend_node_id`, eliminating the need for a
`ExtendImplDecl` struct.

This is part of #6420 which is being split up into a chain of smaller
PRs. It is based on #6465.
This commit is contained in:
Dana Jansens
2025-12-09 22:02:50 +00:00
committed by GitHub
parent c7cd24e1b2
commit b07b8a122a
3 changed files with 104 additions and 108 deletions
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toolchain/check/handle_impl.cpp
+25 -19
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@@ -228,28 +228,34 @@ static auto BuildImplDecl(Context& context, Parse::AnyImplDeclId node_id,
SemIR::ImplDecl{.impl_id = SemIR::ImplId::None,
.decl_block_id = decl_block_id});
SemIR::Impl impl_info = {name_context.MakeEntityWithParamsBase(
name, impl_decl_id,
/*is_extern=*/false, SemIR::LibraryNameId::None),
{.self_id = self_type_inst_id,
.constraint_id = constraint_type_inst_id,
// This requires that the facet type is identified.
.interface = CheckConstraintIsInterface(
context, impl_decl_id, constraint_type_inst_id),
.is_final = is_final}};
// This requires that the facet type is identified. It returns None if an
// error was diagnosed.
auto specific_interface = CheckConstraintIsInterface(context, impl_decl_id,
constraint_type_inst_id);
std::optional<ExtendImplDecl> extend_impl;
if (introducer.modifier_set.HasAnyOf(KeywordModifierSet::Extend)) {
extend_impl = ExtendImplDecl{
.self_type_node_id = self_type_node,
.constraint_type_id = constraint_type_id,
.extend_node_id = introducer.modifier_node_id(ModifierOrder::Extend),
};
auto impl_id = SemIR::ImplId::None;
{
SemIR::Impl impl_info = {
name_context.MakeEntityWithParamsBase(name, impl_decl_id,
/*is_extern=*/false,
SemIR::LibraryNameId::None),
{.self_id = self_type_inst_id,
.constraint_id = constraint_type_inst_id,
.interface = specific_interface,
.is_final = is_final}};
auto extend_node = introducer.modifier_node_id(ModifierOrder::Extend);
impl_id = GetOrAddImpl(context, node_id, name.implicit_params_loc_id,
impl_info, is_definition, extend_node);
}
return StartImplDecl(context, SemIR::LocId(node_id),
name.implicit_params_loc_id, impl_info, is_definition,
extend_impl);
// `GetOrAddImpl` either filled in the `impl_info` and returned a fresh
// ImplId, or if we're redeclaring a previous impl, returned an existing
// ImplId. Write that ImplId into the ImplDecl instruction and finish it.
auto impl_decl = context.insts().GetAs<SemIR::ImplDecl>(impl_decl_id);
impl_decl.impl_id = impl_id;
ReplaceInstBeforeConstantUse(context, impl_decl_id, impl_decl);
return {impl_id, impl_decl_id};
}
auto HandleParseNode(Context& context, Parse::ImplDeclId node_id) -> bool {