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Code Issues Packages Projects Releases 10 Wiki Activity

ImplWitness (#4679)

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* Change `InterfaceWitness` -> `ImplWitness`
* Include a `SpecificId` in the `ImplWitness`. This allows the
`InstBlock` it contains to have its own identity, allowing it to be
changed as the impl is processed. Evaluation only updates the specific.
* Create the `ImplWitness` at the start of the impl definition. In the
future, this will be populated with the values of non-function
associated constants. For now, it starts full of invalid instruction
ids.
* Implements the model suggested in #4672 .

Note that the non-SemIR testdata changes are to these file:
* `toolchain/check/testdata/impl/lookup/fail_todo_undefined_impl.carbon`
* `toolchain/check/testdata/struct/import.carbon`
* `toolchain/check/testdata/tuple/import.carbon`

The last two are due to an import of generics bug exposed by this PR,
which will be fixed in a follow-on.

---------

Co-authored-by: Josh L <josh11b@users.noreply.github.com>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
This commit is contained in:
josh11b
2025-01-02 23:03:11 +00:00
committed by GitHub
co-authored by Josh L Richard Smith
parent 4a7aefefaa
commit c5fd8f42b8
256 changed files with 3060 additions and 2616 deletions
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toolchain/check/impl.cpp
+104 -54
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@@ -34,8 +34,8 @@ static auto NoteAssociatedFunction(Context& context,
// given a specific for an enclosing generic, plus a type to use as `Self`.
static auto GetSelfSpecificForInterfaceMemberWithSelfType(
Context& context, SemIRLoc loc, SemIR::SpecificId enclosing_specific_id,
SemIR::GenericId generic_id, SemIR::TypeId self_type_id)
-> SemIR::SpecificId {
SemIR::GenericId generic_id, SemIR::TypeId self_type_id,
SemIR::InstId witness_inst_id) -> SemIR::SpecificId {
const auto& generic = context.generics().Get(generic_id);
auto bindings = context.inst_blocks().Get(generic.bindings_id);
@@ -61,12 +61,9 @@ static auto GetSelfSpecificForInterfaceMemberWithSelfType(
"Expected a Self binding, found {0}", self_binding);
// Create a facet value to be the value of `Self` in the interface.
// This facet value consists of the type `self_type_id` and a witness that the
// type implements `self_binding.type_id`. The witness needs to be symbolic
// type implements `self_binding.type_id`. Note that the witness is incomplete
// since we haven't finished defining the implementation here.
auto type_inst_id = context.types().GetInstId(self_type_id);
// TODO: Make a symbolic interface witness here. For the moment, the witness
// is never used.
auto witness_inst_id = type_inst_id;
auto facet_value_const_id =
TryEvalInst(context, SemIR::InstId::Invalid,
SemIR::FacetValue{.type_id = self_binding.type_id,
@@ -93,7 +90,8 @@ static auto GetSelfSpecificForInterfaceMemberWithSelfType(
// `BuiltinErrorInst` if the function is not usable.
static auto CheckAssociatedFunctionImplementation(
Context& context, SemIR::FunctionType interface_function_type,
SemIR::InstId impl_decl_id, SemIR::TypeId self_type_id) -> SemIR::InstId {
SemIR::InstId impl_decl_id, SemIR::TypeId self_type_id,
SemIR::InstId witness_inst_id) -> SemIR::InstId {
auto impl_function_decl =
context.insts().TryGetAs<SemIR::FunctionDecl>(impl_decl_id);
if (!impl_function_decl) {
@@ -119,7 +117,7 @@ static auto CheckAssociatedFunctionImplementation(
context.functions()
.Get(interface_function_type.function_id)
.generic_id,
self_type_id);
self_type_id, witness_inst_id);
// TODO: This should be a semantic check rather than a syntactic one. The
// functions should be allowed to have different signatures as long as we can
@@ -134,8 +132,11 @@ static auto CheckAssociatedFunctionImplementation(
return impl_decl_id;
}
// Builds an initial empty witness.
auto ImplWitnessForDeclaration(Context& context, const SemIR::Impl& impl)
-> SemIR::InstId {
CARBON_CHECK(!impl.has_definition_started());
auto facet_type_id = context.GetTypeIdForTypeInst(impl.constraint_id);
if (facet_type_id == SemIR::ErrorInst::SingletonTypeId) {
return SemIR::ErrorInst::SingletonInstId;
@@ -158,6 +159,7 @@ auto ImplWitnessForDeclaration(Context& context, const SemIR::Impl& impl)
}
const auto& interface =
context.interfaces().Get(interface_type->interface_id);
// TODO: This is going to try and define all the interfaces for this facet
// type, and so once we support impl of a facet type with more than one
// interface, it might give the wrong name in the diagnostic.
@@ -172,17 +174,6 @@ auto ImplWitnessForDeclaration(Context& context, const SemIR::Impl& impl)
})) {
return SemIR::ErrorInst::SingletonInstId;
}
return SemIR::InstId::Invalid;
}
// Builds a witness that the specified impl implements the given interface.
static auto BuildInterfaceWitness(
Context& context, const SemIR::Impl& impl,
SemIR::FacetTypeInfo::ImplsConstraint interface_type,
llvm::SmallVectorImpl<SemIR::InstId>& used_decl_ids) -> SemIR::InstId {
const auto& interface = context.interfaces().Get(interface_type.interface_id);
auto& impl_scope = context.name_scopes().Get(impl.scope_id);
auto self_type_id = context.GetTypeIdForTypeInst(impl.self_id);
llvm::SmallVector<SemIR::InstId> table;
auto assoc_entities =
@@ -193,45 +184,29 @@ static auto BuildInterfaceWitness(
LoadImportRef(context, decl_id);
decl_id =
context.constant_values().GetInstId(SemIR::GetConstantValueInSpecific(
context.sem_ir(), interface_type.specific_id, decl_id));
context.sem_ir(), interface_type->specific_id, decl_id));
CARBON_CHECK(decl_id.is_valid(), "Non-constant associated entity");
auto decl = context.insts().Get(decl_id);
CARBON_KIND_SWITCH(decl) {
case CARBON_KIND(SemIR::StructValue struct_value): {
if (struct_value.type_id == SemIR::ErrorInst::SingletonTypeId) {
return SemIR::ErrorInst::SingletonInstId;
table.push_back(SemIR::ErrorInst::SingletonInstId);
break;
}
auto type_inst = context.types().GetAsInst(struct_value.type_id);
auto fn_type = type_inst.TryAs<SemIR::FunctionType>();
if (!fn_type) {
CARBON_FATAL("Unexpected type: {0}", type_inst);
}
auto& fn = context.functions().Get(fn_type->function_id);
auto [impl_decl_id, _] = context.LookupNameInExactScope(
decl_id, fn.name_id, impl.scope_id, impl_scope);
if (impl_decl_id.is_valid()) {
used_decl_ids.push_back(impl_decl_id);
table.push_back(CheckAssociatedFunctionImplementation(
context, *fn_type, impl_decl_id, self_type_id));
} else {
CARBON_DIAGNOSTIC(
ImplMissingFunction, Error,
"missing implementation of {0} in impl of interface {1}",
SemIR::NameId, SemIR::NameId);
auto builder =
context.emitter().Build(impl.definition_id, ImplMissingFunction,
fn.name_id, interface.name_id);
NoteAssociatedFunction(context, builder, fn_type->function_id);
builder.Emit();
table.push_back(SemIR::ErrorInst::SingletonInstId);
}
table.push_back(SemIR::InstId::Invalid);
break;
}
case CARBON_KIND(SemIR::AssociatedConstantDecl associated): {
// TODO: Check we have a value for this constant in the constraint.
// TODO: Allow these using:
// table.push_back(SemIR::InstId::Invalid);
// break;
context.TODO(
impl.definition_id,
impl.latest_decl_id(),
"impl of interface with associated constant " +
context.names().GetFormatted(associated.name_id).str());
return SemIR::ErrorInst::SingletonInstId;
@@ -245,17 +220,27 @@ static auto BuildInterfaceWitness(
}
auto table_id = context.inst_blocks().Add(table);
return context.AddInst<SemIR::InterfaceWitness>(
context.insts().GetLocId(impl.definition_id),
return context.AddInst<SemIR::ImplWitness>(
context.insts().GetLocId(impl.latest_decl_id()),
{.type_id = context.GetSingletonType(SemIR::WitnessType::SingletonInstId),
.elements_id = table_id});
.elements_id = table_id,
.specific_id = context.generics().GetSelfSpecific(impl.generic_id)});
}
auto BuildImplWitness(Context& context, const SemIR::Impl& impl)
-> SemIR::InstId {
auto ImplWitnessStartDefinition(Context& /*context*/, SemIR::Impl& impl)
-> void {
CARBON_CHECK(impl.is_being_defined());
// TODO: Check we have a value for all non-function associated constants in
// the constraint, and fill the witness with them.
return;
}
// Adds functions to the witness that the specified impl implements the given
// interface.
auto FinishImplWitness(Context& context, SemIR::Impl& impl) -> void {
CARBON_CHECK(impl.is_being_defined());
if (impl.witness_id == SemIR::ErrorInst::SingletonInstId) {
return SemIR::ErrorInst::SingletonInstId;
return;
}
auto facet_type_id = context.GetTypeIdForTypeInst(impl.constraint_id);
@@ -264,16 +249,81 @@ auto BuildImplWitness(Context& context, const SemIR::Impl& impl)
const SemIR::FacetTypeInfo& facet_type_info =
context.facet_types().Get(facet_type.facet_type_id);
auto interface = facet_type_info.TryAsSingleInterface();
CARBON_CHECK(interface.has_value());
auto interface_type = facet_type_info.TryAsSingleInterface();
CARBON_CHECK(interface_type.has_value());
const auto& interface =
context.interfaces().Get(interface_type->interface_id);
auto witness = context.insts().GetAs<SemIR::ImplWitness>(impl.witness_id);
auto witness_block = context.inst_blocks().GetMutable(witness.elements_id);
auto& impl_scope = context.name_scopes().Get(impl.scope_id);
auto self_type_id = context.GetTypeIdForTypeInst(impl.self_id);
auto assoc_entities =
context.inst_blocks().Get(interface.associated_entities_id);
llvm::SmallVector<SemIR::InstId> used_decl_ids;
auto witness_id =
BuildInterfaceWitness(context, impl, *interface, used_decl_ids);
for (auto index : llvm::seq(assoc_entities.size())) {
auto decl_id = assoc_entities[index];
decl_id =
context.constant_values().GetInstId(SemIR::GetConstantValueInSpecific(
context.sem_ir(), interface_type->specific_id, decl_id));
CARBON_CHECK(decl_id.is_valid(), "Non-constant associated entity");
auto decl = context.insts().Get(decl_id);
CARBON_KIND_SWITCH(decl) {
case CARBON_KIND(SemIR::StructValue struct_value): {
if (struct_value.type_id == SemIR::ErrorInst::SingletonTypeId) {
break;
}
auto type_inst = context.types().GetAsInst(struct_value.type_id);
auto fn_type = type_inst.As<SemIR::FunctionType>();
auto& fn = context.functions().Get(fn_type.function_id);
auto [impl_decl_id, _] = context.LookupNameInExactScope(
decl_id, fn.name_id, impl.scope_id, impl_scope);
if (impl_decl_id.is_valid()) {
used_decl_ids.push_back(impl_decl_id);
witness_block[index] = CheckAssociatedFunctionImplementation(
context, fn_type, impl_decl_id, self_type_id, impl.witness_id);
} else {
CARBON_DIAGNOSTIC(
ImplMissingFunction, Error,
"missing implementation of {0} in impl of interface {1}",
SemIR::NameId, SemIR::NameId);
auto builder =
context.emitter().Build(impl.definition_id, ImplMissingFunction,
fn.name_id, interface.name_id);
NoteAssociatedFunction(context, builder, fn_type.function_id);
builder.Emit();
witness_block[index] = SemIR::ErrorInst::SingletonInstId;
}
break;
}
case SemIR::AssociatedConstantDecl::Kind: {
// These are set to their final values already.
break;
}
default:
CARBON_CHECK(decl_id == SemIR::ErrorInst::SingletonInstId,
"Unexpected kind of associated entity {0}", decl);
// These are set to their final values already.
break;
}
}
// TODO: Diagnose if any declarations in the impl are not in used_decl_ids.
}
return witness_id;
auto FillImplWitnessWithErrors(Context& context, SemIR::Impl& impl) -> void {
if (impl.witness_id.is_valid() &&
impl.witness_id != SemIR::ErrorInst::SingletonInstId) {
auto witness = context.insts().GetAs<SemIR::ImplWitness>(impl.witness_id);
auto witness_block = context.inst_blocks().GetMutable(witness.elements_id);
for (auto& elem : witness_block) {
if (!elem.is_valid()) {
elem = SemIR::ErrorInst::SingletonInstId;
}
}
}
}
} // namespace Carbon::Check