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First iteration of completing and resolving facet types (#4920)

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* Add `RequireCompleteFacetType` and `ResolveFacetTypeImplWitness` to
`check::Context`. Goal was to move code from `impl.cpp` (mostly) without
functional changes.
* Complete type information is cached with the facet type, and is stored
in a `complete_facet_types()` table.
* Main functional change is to diagnose attempts to use a rewrite
constraint on an associated function. Some existing diagnostics have
been updated.
* Remove `check::Context::RequireDefinedType`:
  * For class types, use `RequireCompleteType`
  * For facet types, use `RequireCompleteFacetType`
* Introduce a `SemIR::SpecificInterface` to hold an interface and
specific id pair.
* Keep the specific interface ids in the impl object.
* Avoid some extra copies in `Dump` functions.
* Future work missing from this PR:
  * Resolving for member access or actions that require impl lookup.
  * Resolving rewrites constraints that refer to non-concrete values.
* Any support for adding implied constraints that result from a `where`
clause (though TODOs have been added).

---------

Co-authored-by: Josh L <josh11b@users.noreply.github.com>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Co-authored-by: Dana Jansens <danakj@orodu.net>
This commit is contained in:
josh11b
2025-02-19 22:10:11 +00:00
committed by GitHub
co-authored by Josh L Richard Smith Dana Jansens
parent 7c7e169994
commit eb69d7420e
46 changed files with 982 additions and 476 deletions
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toolchain/check/impl.cpp
+7 -218
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@@ -6,8 +6,8 @@
#include "toolchain/base/kind_switch.h"
#include "toolchain/check/context.h"
#include "toolchain/check/convert.h"
#include "toolchain/check/eval.h"
#include "toolchain/check/facet_type.h"
#include "toolchain/check/function.h"
#include "toolchain/check/generic.h"
#include "toolchain/check/import_ref.h"
@@ -91,198 +91,11 @@ auto ImplWitnessForDeclaration(Context& context, const SemIR::Impl& impl)
// When 'impl as' is invalid, the self type is an error.
return SemIR::ErrorInst::SingletonInstId;
}
auto facet_type_id =
context.types().GetTypeIdForTypeInstId(impl.constraint_id);
if (facet_type_id == SemIR::ErrorInst::SingletonTypeId) {
return SemIR::ErrorInst::SingletonInstId;
}
auto facet_type = context.types().TryGetAs<SemIR::FacetType>(facet_type_id);
if (!facet_type) {
CARBON_DIAGNOSTIC(ImplAsNonFacetType, Error, "impl as non-facet type {0}",
InstIdAsType);
context.emitter().Emit(impl.latest_decl_id(), ImplAsNonFacetType,
impl.constraint_id);
return SemIR::ErrorInst::SingletonInstId;
}
const SemIR::FacetTypeInfo& facet_type_info =
context.facet_types().Get(facet_type->facet_type_id);
auto interface_type = facet_type_info.TryAsSingleInterface();
if (!interface_type) {
context.TODO(impl.latest_decl_id(), "impl as not 1 interface");
return SemIR::ErrorInst::SingletonInstId;
}
const auto& interface =
context.interfaces().Get(interface_type->interface_id);
// TODO: This should be done as part of facet type resolution.
if (!RequireDefinedType(context, facet_type_id,
context.insts().GetLocId(impl.latest_decl_id()), [&] {
CARBON_DIAGNOSTIC(
ImplOfUndefinedInterface, Error,
"implementation of undefined interface {0}",
SemIR::NameId);
return context.emitter().Build(
impl.latest_decl_id(), ImplOfUndefinedInterface,
interface.name_id);
})) {
return SemIR::ErrorInst::SingletonInstId;
}
auto assoc_entities =
context.inst_blocks().Get(interface.associated_entities_id);
for (auto decl_id : assoc_entities) {
LoadImportRef(context, decl_id);
}
llvm::SmallVector<SemIR::InstId> table(assoc_entities.size(),
SemIR::InstId::None);
auto table_id = context.inst_blocks().Add(table);
return AddInst<SemIR::ImplWitness>(
return ResolveFacetTypeImplWitness(
context, context.insts().GetLocId(impl.latest_decl_id()),
{.type_id =
GetSingletonType(context, SemIR::WitnessType::SingletonInstId),
.elements_id = table_id,
.specific_id = context.generics().GetSelfSpecific(impl.generic_id)});
}
// Returns `true` if the `FacetAccessWitness` of `witness_id` matches
// `interface`.
static auto WitnessAccessMatchesInterface(
Context& context, SemIR::InstId witness_id,
SemIR::FacetTypeInfo::ImplsConstraint interface) -> bool {
auto access = context.insts().GetAs<SemIR::FacetAccessWitness>(witness_id);
auto type_id = context.insts().Get(access.facet_value_inst_id).type_id();
auto facet_type = context.types().GetAs<SemIR::FacetType>(type_id);
const auto& facet_info = context.facet_types().Get(facet_type.facet_type_id);
if (auto impls = facet_info.TryAsSingleInterface()) {
return *impls == interface;
}
return false;
}
// TODO: Merge this function into `ImplWitnessForDeclaration`.
auto AddConstantsToImplWitnessFromConstraint(Context& context,
const SemIR::Impl& impl,
SemIR::InstId witness_id) -> void {
CARBON_CHECK(!impl.has_definition_started());
CARBON_CHECK(witness_id.has_value());
if (witness_id == SemIR::ErrorInst::SingletonInstId) {
return;
}
auto facet_type_id =
context.types().GetTypeIdForTypeInstId(impl.constraint_id);
CARBON_CHECK(facet_type_id != SemIR::ErrorInst::SingletonTypeId);
auto facet_type = context.types().GetAs<SemIR::FacetType>(facet_type_id);
const SemIR::FacetTypeInfo& facet_type_info =
context.facet_types().Get(facet_type.facet_type_id);
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>(witness_id);
auto witness_block = context.inst_blocks().GetMutable(witness.elements_id);
auto assoc_entities =
context.inst_blocks().Get(interface.associated_entities_id);
CARBON_CHECK(witness_block.size() == assoc_entities.size());
// Scan through rewrites, produce map from element index to constant value.
// TODO: Perhaps move this into facet type resolution?
llvm::SmallVector<SemIR::ConstantId> rewrite_values(assoc_entities.size(),
SemIR::ConstantId::None);
for (auto rewrite : facet_type_info.rewrite_constraints) {
auto inst_id = context.constant_values().GetInstId(rewrite.lhs_const_id);
auto access = context.insts().GetAs<SemIR::ImplWitnessAccess>(inst_id);
if (!WitnessAccessMatchesInterface(context, access.witness_id,
*interface_type)) {
// Skip rewrite constraints that apply to associated constants of
// a different interface than the one being implemented.
continue;
}
CARBON_CHECK(access.index.index >= 0);
CARBON_CHECK(access.index.index <
static_cast<int32_t>(rewrite_values.size()));
auto& rewrite_value = rewrite_values[access.index.index];
if (rewrite_value.has_value() &&
rewrite_value != SemIR::ErrorInst::SingletonConstantId) {
if (rewrite_value != rewrite.rhs_const_id &&
rewrite.rhs_const_id != SemIR::ErrorInst::SingletonConstantId) {
// TODO: Do at least this checking as part of facet type resolution
// instead.
// TODO: Figure out how to print the two different values
// `rewrite_value` & `rewrite.rhs_const_id` in the diagnostic message.
CARBON_DIAGNOSTIC(AssociatedConstantWithDifferentValues, Error,
"associated constant {0} given two different values",
SemIR::NameId);
auto decl_id = context.constant_values().GetConstantInstId(
assoc_entities[access.index.index]);
CARBON_CHECK(decl_id.has_value(), "Non-constant associated entity");
auto decl =
context.insts().GetAs<SemIR::AssociatedConstantDecl>(decl_id);
context.emitter().Emit(
impl.constraint_id, AssociatedConstantWithDifferentValues,
context.associated_constants().Get(decl.assoc_const_id).name_id);
}
} else {
rewrite_value = rewrite.rhs_const_id;
}
}
// For each non-function associated constant, set the witness entry.
for (auto index : llvm::seq(assoc_entities.size())) {
auto decl_id =
context.constant_values().GetConstantInstId(assoc_entities[index]);
CARBON_CHECK(decl_id.has_value(), "Non-constant associated entity");
if (auto decl =
context.insts().TryGetAs<SemIR::AssociatedConstantDecl>(decl_id)) {
auto rewrite_value = rewrite_values[index];
// If the associated constant has a symbolic type, convert the rewrite
// value to that type now we know the value of `Self`.
SemIR::TypeId assoc_const_type_id = decl->type_id;
if (context.types().GetConstantId(assoc_const_type_id).is_symbolic()) {
// Get the type of the associated constant in this interface with this
// value for `Self`.
assoc_const_type_id = GetTypeForSpecificAssociatedEntity(
context, impl.constraint_id, interface_type->specific_id, decl_id,
context.types().GetTypeIdForTypeInstId(impl.self_id), witness_id);
// Perform the conversion of the value to the type. We skipped this when
// forming the facet type because the type of the associated constant
// was symbolic.
auto converted_inst_id = ConvertToValueOfType(
context, context.insts().GetLocId(impl.constraint_id),
context.constant_values().GetInstId(rewrite_value),
assoc_const_type_id);
rewrite_value = context.constant_values().Get(converted_inst_id);
// The result of conversion can be non-constant even if the original
// value was constant.
if (!rewrite_value.is_constant() &&
rewrite_value != SemIR::ErrorInst::SingletonConstantId) {
const auto& assoc_const =
context.associated_constants().Get(decl->assoc_const_id);
CARBON_DIAGNOSTIC(
AssociatedConstantNotConstantAfterConversion, Error,
"associated constant {0} given value that is not constant "
"after conversion to {1}",
SemIR::NameId, SemIR::TypeId);
context.emitter().Emit(impl.constraint_id,
AssociatedConstantNotConstantAfterConversion,
assoc_const.name_id, assoc_const_type_id);
rewrite_value = SemIR::ErrorInst::SingletonConstantId;
}
}
if (rewrite_value.has_value()) {
witness_block[index] =
context.constant_values().GetInstId(rewrite_value);
}
}
}
impl.constraint_id, impl.self_id, impl.interface,
context.generics().GetSelfSpecific(impl.generic_id));
}
auto ImplWitnessStartDefinition(Context& context, SemIR::Impl& impl) -> void {
@@ -291,21 +104,9 @@ auto ImplWitnessStartDefinition(Context& context, SemIR::Impl& impl) -> void {
if (impl.witness_id == SemIR::ErrorInst::SingletonInstId) {
return;
}
auto facet_type_id =
context.types().GetTypeIdForTypeInstId(impl.constraint_id);
CARBON_CHECK(facet_type_id != SemIR::ErrorInst::SingletonTypeId);
auto facet_type = context.types().GetAs<SemIR::FacetType>(facet_type_id);
const SemIR::FacetTypeInfo& facet_type_info =
context.facet_types().Get(facet_type.facet_type_id);
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);
const auto& interface = context.interfaces().Get(impl.interface.interface_id);
auto assoc_entities =
context.inst_blocks().Get(interface.associated_entities_id);
CARBON_CHECK(witness_block.size() == assoc_entities.size());
@@ -349,23 +150,11 @@ auto FinishImplWitness(Context& context, SemIR::Impl& impl) -> void {
if (impl.witness_id == SemIR::ErrorInst::SingletonInstId) {
return;
}
auto facet_type_id =
context.types().GetTypeIdForTypeInstId(impl.constraint_id);
CARBON_CHECK(facet_type_id != SemIR::ErrorInst::SingletonTypeId);
auto facet_type = context.types().GetAs<SemIR::FacetType>(facet_type_id);
const SemIR::FacetTypeInfo& facet_type_info =
context.facet_types().Get(facet_type.facet_type_id);
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.types().GetTypeIdForTypeInstId(impl.self_id);
const auto& interface = context.interfaces().Get(impl.interface.interface_id);
auto assoc_entities =
context.inst_blocks().Get(interface.associated_entities_id);
llvm::SmallVector<SemIR::InstId> used_decl_ids;
@@ -374,7 +163,7 @@ auto FinishImplWitness(Context& context, SemIR::Impl& impl) -> void {
auto decl_id = assoc_entities[index];
decl_id =
context.constant_values().GetInstId(SemIR::GetConstantValueInSpecific(
context.sem_ir(), interface_type->specific_id, decl_id));
context.sem_ir(), impl.interface.specific_id, decl_id));
CARBON_CHECK(decl_id.has_value(), "Non-constant associated entity");
auto decl = context.insts().Get(decl_id);
CARBON_KIND_SWITCH(decl) {