mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 22:02:23 +01:00
Jon Ross-Perkins
9c0faf007e
This is a followup from #4834, I searched for "invalid" uses in our codebase. This is mostly changing comments, and a couple debug functions, but shouldn't affect testable behavior. Note a couple things I'll highlight as not changing (but could) are: - `ReturnTypeInfo::is_valid` - `"invalid"` uses in the formatter - `AddInvalid` for `!has_value` in `inst_fingerprinter` (because the cases it's called sound invalid-ish)
557 lines
22 KiB
C++
557 lines
22 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "toolchain/check/deduce.h"
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#include "llvm/ADT/SmallBitVector.h"
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#include "toolchain/base/kind_switch.h"
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#include "toolchain/check/context.h"
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#include "toolchain/check/convert.h"
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#include "toolchain/check/generic.h"
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#include "toolchain/check/subst.h"
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#include "toolchain/sem_ir/ids.h"
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#include "toolchain/sem_ir/impl.h"
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#include "toolchain/sem_ir/typed_insts.h"
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namespace Carbon::Check {
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namespace {
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// A list of pairs of (instruction from generic, corresponding instruction from
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// call to of generic) for which we still need to perform deduction, along with
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// methods to add and pop pending deductions from the list. Deductions are
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// popped in order from most- to least-recently pushed, with the intent that
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// they are visited in depth-first order, although the order is not expected to
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// matter except when it influences which error is diagnosed.
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class DeductionWorklist {
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public:
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explicit DeductionWorklist(Context& context) : context_(context) {}
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struct PendingDeduction {
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SemIR::InstId param;
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SemIR::InstId arg;
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bool needs_substitution;
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};
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// Adds a single (param, arg) deduction.
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auto Add(SemIR::InstId param, SemIR::InstId arg, bool needs_substitution)
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-> void {
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deductions_.push_back(
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{.param = param, .arg = arg, .needs_substitution = needs_substitution});
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}
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// Adds a single (param, arg) type deduction.
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auto Add(SemIR::TypeId param, SemIR::TypeId arg, bool needs_substitution)
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-> void {
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Add(context_.types().GetInstId(param), context_.types().GetInstId(arg),
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needs_substitution);
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}
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// Adds a single (param, arg) deduction of a specific.
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auto Add(SemIR::SpecificId param, SemIR::SpecificId arg,
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bool needs_substitution) -> void {
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if (!param.has_value() || !arg.has_value()) {
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return;
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}
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auto& param_specific = context_.specifics().Get(param);
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auto& arg_specific = context_.specifics().Get(arg);
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if (param_specific.generic_id != arg_specific.generic_id) {
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// TODO: Decide whether to error on this or just treat the specific as
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// non-deduced. For now we treat it as non-deduced.
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return;
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}
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AddAll(param_specific.args_id, arg_specific.args_id, needs_substitution);
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}
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// Adds a list of (param, arg) deductions. These are added in reverse order so
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// they are popped in forward order.
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template <typename ElementId>
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auto AddAll(llvm::ArrayRef<ElementId> params, llvm::ArrayRef<ElementId> args,
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bool needs_substitution) -> void {
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if (params.size() != args.size()) {
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// TODO: Decide whether to error on this or just treat the parameter list
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// as non-deduced. For now we treat it as non-deduced.
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return;
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}
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for (auto [param, arg] : llvm::reverse(llvm::zip_equal(params, args))) {
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Add(param, arg, needs_substitution);
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}
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}
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auto AddAll(SemIR::InstBlockId params, llvm::ArrayRef<SemIR::InstId> args,
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bool needs_substitution) -> void {
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AddAll(context_.inst_blocks().Get(params), args, needs_substitution);
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}
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auto AddAll(SemIR::StructTypeFieldsId params, SemIR::StructTypeFieldsId args,
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bool needs_substitution) -> void {
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const auto& param_fields = context_.struct_type_fields().Get(params);
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const auto& arg_fields = context_.struct_type_fields().Get(args);
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if (param_fields.size() != arg_fields.size()) {
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// TODO: Decide whether to error on this or just treat the parameter list
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// as non-deduced. For now we treat it as non-deduced.
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return;
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}
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// Don't do deduction unless the names match in order.
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// TODO: Support reordering of names.
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for (auto [param, arg] : llvm::zip_equal(param_fields, arg_fields)) {
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if (param.name_id != arg.name_id) {
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return;
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}
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}
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for (auto [param, arg] :
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llvm::reverse(llvm::zip_equal(param_fields, arg_fields))) {
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Add(param.type_id, arg.type_id, needs_substitution);
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}
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}
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auto AddAll(SemIR::InstBlockId params, SemIR::InstBlockId args,
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bool needs_substitution) -> void {
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AddAll(context_.inst_blocks().Get(params), context_.inst_blocks().Get(args),
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needs_substitution);
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}
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auto AddAll(SemIR::TypeBlockId params, SemIR::TypeBlockId args,
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bool needs_substitution) -> void {
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AddAll(context_.type_blocks().Get(params), context_.type_blocks().Get(args),
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needs_substitution);
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}
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auto AddAll(SemIR::FacetTypeId params, SemIR::FacetTypeId args,
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bool needs_substitution) -> void {
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const auto& param_impls =
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context_.facet_types().Get(params).impls_constraints;
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const auto& arg_impls = context_.facet_types().Get(args).impls_constraints;
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// TODO: Decide whether to error on these or just treat the parameter list
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// as non-deduced. For now we treat it as non-deduced.
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if (param_impls.size() != 1 || arg_impls.size() != 1) {
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return;
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}
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auto param = param_impls.front();
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auto arg = arg_impls.front();
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if (param.interface_id != arg.interface_id) {
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return;
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}
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Add(param.specific_id, arg.specific_id, needs_substitution);
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}
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// Adds a (param, arg) pair for an instruction argument, given its kind.
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auto AddInstArg(SemIR::IdKind kind, int32_t param, int32_t arg,
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bool needs_substitution) -> void {
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switch (kind) {
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case SemIR::IdKind::None:
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case SemIR::IdKind::For<SemIR::ClassId>:
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case SemIR::IdKind::For<SemIR::IntKind>:
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break;
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case SemIR::IdKind::For<SemIR::InstId>:
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Add(SemIR::InstId(param), SemIR::InstId(arg), needs_substitution);
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break;
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case SemIR::IdKind::For<SemIR::TypeId>:
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Add(SemIR::TypeId(param), SemIR::TypeId(arg), needs_substitution);
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break;
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case SemIR::IdKind::For<SemIR::StructTypeFieldsId>:
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AddAll(SemIR::StructTypeFieldsId(param), SemIR::StructTypeFieldsId(arg),
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needs_substitution);
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break;
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case SemIR::IdKind::For<SemIR::InstBlockId>:
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AddAll(SemIR::InstBlockId(param), SemIR::InstBlockId(arg),
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needs_substitution);
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break;
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case SemIR::IdKind::For<SemIR::TypeBlockId>:
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AddAll(SemIR::TypeBlockId(param), SemIR::TypeBlockId(arg),
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needs_substitution);
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break;
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case SemIR::IdKind::For<SemIR::SpecificId>:
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Add(SemIR::SpecificId(param), SemIR::SpecificId(arg),
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needs_substitution);
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break;
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case SemIR::IdKind::For<SemIR::FacetTypeId>:
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AddAll(SemIR::FacetTypeId(param), SemIR::FacetTypeId(arg),
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needs_substitution);
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break;
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default:
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CARBON_FATAL("unexpected argument kind");
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}
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}
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// Returns whether we have completed all deductions.
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auto Done() -> bool { return deductions_.empty(); }
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// Pops the next deduction. Requires `!Done()`.
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auto PopNext() -> PendingDeduction { return deductions_.pop_back_val(); }
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private:
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Context& context_;
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llvm::SmallVector<PendingDeduction> deductions_;
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};
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// State that is tracked throughout the deduction process.
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class DeductionContext {
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public:
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// Preparse to perform deduction. If an enclosing specific is provided, adds
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// the arguments from the given specific as known arguments that will not be
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// deduced.
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DeductionContext(Context& context, SemIR::LocId loc_id,
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SemIR::GenericId generic_id,
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SemIR::SpecificId enclosing_specific_id, bool diagnose);
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auto context() const -> Context& { return *context_; }
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// Adds a pending deduction of `param` from `arg`. `needs_substitution`
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// indicates whether we need to substitute known generic parameters into
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// `param`.
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template <typename ParamT, typename ArgT>
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auto Add(ParamT param, ArgT arg, bool needs_substitution) -> void {
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worklist_.Add(param, arg, needs_substitution);
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}
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// Same as `Add` but for an array or block of operands.
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template <typename ParamT, typename ArgT>
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auto AddAll(ParamT param, ArgT arg, bool needs_substitution) -> void {
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worklist_.AddAll(param, arg, needs_substitution);
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}
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// Performs all deductions in the deduction worklist. Returns whether
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// deduction succeeded.
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auto Deduce() -> bool;
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// Returns whether every generic parameter has a corresponding deduced generic
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// argument. If not, issues a suitable diagnostic.
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auto CheckDeductionIsComplete() -> bool;
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// Forms a specific corresponding to the deduced generic with the deduced
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// argument list. Must not be called before deduction is complete.
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auto MakeSpecific() -> SemIR::SpecificId;
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private:
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Context* context_;
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SemIR::LocId loc_id_;
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SemIR::GenericId generic_id_;
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bool diagnose_;
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DeductionWorklist worklist_;
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llvm::SmallVector<SemIR::InstId> result_arg_ids_;
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llvm::SmallVector<Substitution> substitutions_;
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SemIR::CompileTimeBindIndex first_deduced_index_;
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// Non-deduced indexes, indexed by parameter index - first_deduced_index_.
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llvm::SmallBitVector non_deduced_indexes_;
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};
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} // namespace
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static auto NoteGenericHere(Context& context, SemIR::GenericId generic_id,
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Context::DiagnosticBuilder& diag) -> void {
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CARBON_DIAGNOSTIC(DeductionGenericHere, Note,
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"while deducing parameters of generic declared here");
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diag.Note(context.generics().Get(generic_id).decl_id, DeductionGenericHere);
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}
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DeductionContext::DeductionContext(Context& context, SemIR::LocId loc_id,
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SemIR::GenericId generic_id,
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SemIR::SpecificId enclosing_specific_id,
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bool diagnose)
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: context_(&context),
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loc_id_(loc_id),
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generic_id_(generic_id),
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diagnose_(diagnose),
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worklist_(context),
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first_deduced_index_(0) {
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CARBON_CHECK(generic_id.has_value(),
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"Performing deduction for non-generic entity");
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// Initialize the deduced arguments to `None`.
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result_arg_ids_.resize(
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context.inst_blocks()
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.Get(context.generics().Get(generic_id_).bindings_id)
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.size(),
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SemIR::InstId::None);
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if (enclosing_specific_id.has_value()) {
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// Copy any outer generic arguments from the specified instance and prepare
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// to substitute them into the function declaration.
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auto args = context.inst_blocks().Get(
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context.specifics().Get(enclosing_specific_id).args_id);
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llvm::copy(args, result_arg_ids_.begin());
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// TODO: Subst is linear in the length of the substitutions list. Change
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// it so we can pass in an array mapping indexes to substitutions instead.
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substitutions_.reserve(args.size());
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for (auto [i, subst_inst_id] : llvm::enumerate(args)) {
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substitutions_.push_back(
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{.bind_id = SemIR::CompileTimeBindIndex(i),
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.replacement_id = context.constant_values().Get(subst_inst_id)});
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}
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first_deduced_index_ = SemIR::CompileTimeBindIndex(args.size());
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}
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non_deduced_indexes_.resize(result_arg_ids_.size() -
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first_deduced_index_.index);
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}
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auto DeductionContext::Deduce() -> bool {
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while (!worklist_.Done()) {
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auto [param_id, arg_id, needs_substitution] = worklist_.PopNext();
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auto note_initializing_param = [&](auto& builder) {
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if (auto param =
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context().insts().TryGetAs<SemIR::SymbolicBindingPattern>(
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param_id)) {
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CARBON_DIAGNOSTIC(InitializingGenericParam, Note,
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"initializing generic parameter `{0}` declared here",
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SemIR::NameId);
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builder.Note(
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param_id, InitializingGenericParam,
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context().entity_names().Get(param->entity_name_id).name_id);
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} else {
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NoteGenericHere(context(), generic_id_, builder);
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}
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};
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// TODO: Bail out if there's nothing to deduce: if we're not in a pattern
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// and the parameter doesn't have a symbolic constant value.
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// If the parameter has a symbolic type, deduce against that.
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auto param_type_id = context().insts().Get(param_id).type_id();
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if (param_type_id.AsConstantId().is_symbolic()) {
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Add(context().types().GetInstId(param_type_id),
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context().types().GetInstId(context().insts().Get(arg_id).type_id()),
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needs_substitution);
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} else {
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// The argument needs to have the same type as the parameter.
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// TODO: Suppress diagnostics here if diagnose_ is false.
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// TODO: Only do this when deducing against a symbolic pattern.
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DiagnosticAnnotationScope annotate_diagnostics(&context().emitter(),
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note_initializing_param);
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arg_id = ConvertToValueOfType(context(), loc_id_, arg_id, param_type_id);
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if (arg_id == SemIR::ErrorInst::SingletonInstId) {
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return false;
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}
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}
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// Attempt to match `param_inst` against `arg_id`. If the match succeeds,
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// this should `continue` the outer loop. On `break`, we will try to desugar
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// the parameter to continue looking for a match.
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auto param_inst = context().insts().Get(param_id);
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CARBON_KIND_SWITCH(param_inst) {
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// Deducing a symbolic binding pattern from an argument deduces the
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// binding as having that constant value. For example, deducing
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// `(T:! type)` against `(i32)` deduces `T` to be `i32`. This only arises
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// when initializing a generic parameter from an explicitly specified
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// argument, and in this case, the argument is required to be a
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// compile-time constant.
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case CARBON_KIND(SemIR::SymbolicBindingPattern bind): {
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auto& entity_name = context().entity_names().Get(bind.entity_name_id);
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auto index = entity_name.bind_index;
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if (!index.has_value()) {
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break;
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}
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CARBON_CHECK(
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index >= first_deduced_index_ &&
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static_cast<size_t>(index.index) < result_arg_ids_.size(),
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"Unexpected index {0} for symbolic binding pattern; "
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"expected to be in range [{1}, {2})",
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index.index, first_deduced_index_.index, result_arg_ids_.size());
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CARBON_CHECK(!result_arg_ids_[index.index].has_value(),
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"Deduced a value for parameter prior to its declaration");
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auto arg_const_inst_id =
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context().constant_values().GetConstantInstId(arg_id);
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if (!arg_const_inst_id.has_value()) {
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if (diagnose_) {
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CARBON_DIAGNOSTIC(CompTimeArgumentNotConstant, Error,
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"argument for generic parameter is not a "
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"compile-time constant");
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auto diag =
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context().emitter().Build(loc_id_, CompTimeArgumentNotConstant);
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note_initializing_param(diag);
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diag.Emit();
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}
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return false;
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}
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result_arg_ids_[index.index] = arg_const_inst_id;
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// This parameter index should not be deduced if it appears later.
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non_deduced_indexes_[index.index - first_deduced_index_.index] = true;
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continue;
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}
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// Deducing a symbolic binding appearing within an expression against a
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// constant value deduces the binding as having that value. For example,
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// deducing `[T:! type](x: T)` against `("foo")` deduces `T` as `String`.
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case CARBON_KIND(SemIR::BindSymbolicName bind): {
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auto& entity_name = context().entity_names().Get(bind.entity_name_id);
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auto index = entity_name.bind_index;
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if (!index.has_value() || index < first_deduced_index_ ||
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non_deduced_indexes_[index.index - first_deduced_index_.index]) {
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break;
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}
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CARBON_CHECK(static_cast<size_t>(index.index) < result_arg_ids_.size(),
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"Deduced value for unexpected index {0}; expected to "
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"deduce {1} arguments.",
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index, result_arg_ids_.size());
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auto arg_const_inst_id =
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context().constant_values().GetConstantInstId(arg_id);
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if (arg_const_inst_id.has_value()) {
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if (result_arg_ids_[index.index].has_value() &&
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result_arg_ids_[index.index] != arg_const_inst_id) {
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if (diagnose_) {
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// TODO: Include the two different deduced values.
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CARBON_DIAGNOSTIC(DeductionInconsistent, Error,
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"inconsistent deductions for value of generic "
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"parameter `{0}`",
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SemIR::NameId);
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auto diag = context().emitter().Build(
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loc_id_, DeductionInconsistent, entity_name.name_id);
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NoteGenericHere(context(), generic_id_, diag);
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diag.Emit();
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}
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return false;
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}
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result_arg_ids_[index.index] = arg_const_inst_id;
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}
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continue;
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}
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case CARBON_KIND(SemIR::ValueParamPattern pattern): {
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Add(pattern.subpattern_id, arg_id, needs_substitution);
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continue;
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}
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case SemIR::StructValue::Kind:
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// TODO: Match field name order between param and arg.
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break;
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// TODO: Handle more cases.
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default:
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if (param_inst.kind().deduce_through()) {
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// Various kinds of parameter should match an argument of the same
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// form, if the operands all match.
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auto arg_inst = context().insts().Get(arg_id);
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if (arg_inst.kind() != param_inst.kind()) {
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break;
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}
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auto [kind0, kind1] = param_inst.ArgKinds();
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worklist_.AddInstArg(kind0, param_inst.arg0(), arg_inst.arg0(),
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needs_substitution);
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worklist_.AddInstArg(kind1, param_inst.arg1(), arg_inst.arg1(),
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needs_substitution);
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continue;
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}
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break;
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}
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// We didn't manage to deduce against the syntactic form of the parameter.
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// Convert it to a canonical constant value and try deducing against that.
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auto param_const_id = context().constant_values().Get(param_id);
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if (!param_const_id.has_value() || !param_const_id.is_symbolic()) {
|
|
// It's not a symbolic constant. There's nothing here to deduce.
|
|
continue;
|
|
}
|
|
auto param_const_inst_id =
|
|
context().constant_values().GetInstId(param_const_id);
|
|
if (param_const_inst_id != param_id) {
|
|
Add(param_const_inst_id, arg_id, needs_substitution);
|
|
continue;
|
|
}
|
|
|
|
// If we've not yet substituted into the parameter, do so now and try again.
|
|
if (needs_substitution) {
|
|
param_const_id = SubstConstant(context(), param_const_id, substitutions_);
|
|
if (!param_const_id.has_value() || !param_const_id.is_symbolic()) {
|
|
continue;
|
|
}
|
|
Add(context().constant_values().GetInstId(param_const_id), arg_id,
|
|
/*needs_substitution=*/false);
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
auto DeductionContext::CheckDeductionIsComplete() -> bool {
|
|
// Check we deduced an argument value for every parameter.
|
|
for (auto [i, deduced_arg_id] :
|
|
llvm::enumerate(llvm::ArrayRef(result_arg_ids_)
|
|
.drop_front(first_deduced_index_.index))) {
|
|
if (!deduced_arg_id.has_value()) {
|
|
if (diagnose_) {
|
|
auto binding_index = first_deduced_index_.index + i;
|
|
auto binding_id = context().inst_blocks().Get(
|
|
context().generics().Get(generic_id_).bindings_id)[binding_index];
|
|
auto entity_name_id = context()
|
|
.insts()
|
|
.GetAs<SemIR::AnyBindName>(binding_id)
|
|
.entity_name_id;
|
|
CARBON_DIAGNOSTIC(DeductionIncomplete, Error,
|
|
"cannot deduce value for generic parameter `{0}`",
|
|
SemIR::NameId);
|
|
auto diag = context().emitter().Build(
|
|
loc_id_, DeductionIncomplete,
|
|
context().entity_names().Get(entity_name_id).name_id);
|
|
NoteGenericHere(context(), generic_id_, diag);
|
|
diag.Emit();
|
|
}
|
|
return false;
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
auto DeductionContext::MakeSpecific() -> SemIR::SpecificId {
|
|
// TODO: Convert the deduced values to the types of the bindings.
|
|
|
|
return Check::MakeSpecific(
|
|
context(), loc_id_, generic_id_,
|
|
context().inst_blocks().AddCanonical(result_arg_ids_));
|
|
}
|
|
|
|
auto DeduceGenericCallArguments(
|
|
Context& context, SemIR::LocId loc_id, SemIR::GenericId generic_id,
|
|
SemIR::SpecificId enclosing_specific_id,
|
|
[[maybe_unused]] SemIR::InstBlockId implicit_params_id,
|
|
SemIR::InstBlockId params_id, [[maybe_unused]] SemIR::InstId self_id,
|
|
llvm::ArrayRef<SemIR::InstId> arg_ids) -> SemIR::SpecificId {
|
|
DeductionContext deduction(context, loc_id, generic_id, enclosing_specific_id,
|
|
/*diagnose=*/true);
|
|
|
|
// Prepare to perform deduction of the explicit parameters against their
|
|
// arguments.
|
|
// TODO: Also perform deduction for type of self.
|
|
deduction.AddAll(params_id, arg_ids, /*needs_substitution=*/true);
|
|
|
|
if (!deduction.Deduce() || !deduction.CheckDeductionIsComplete()) {
|
|
return SemIR::SpecificId::None;
|
|
}
|
|
|
|
return deduction.MakeSpecific();
|
|
}
|
|
|
|
// Deduces the impl arguments to use in a use of a parameterized impl. Returns
|
|
// `None` if deduction fails.
|
|
auto DeduceImplArguments(Context& context, SemIR::LocId loc_id,
|
|
const SemIR::Impl& impl, SemIR::ConstantId self_id,
|
|
SemIR::ConstantId constraint_id) -> SemIR::SpecificId {
|
|
DeductionContext deduction(context, loc_id, impl.generic_id,
|
|
/*enclosing_specific_id=*/SemIR::SpecificId::None,
|
|
/*diagnose=*/false);
|
|
|
|
// Prepare to perform deduction of the type and interface.
|
|
deduction.Add(impl.self_id, context.constant_values().GetInstId(self_id),
|
|
/*needs_substitution=*/false);
|
|
deduction.Add(impl.constraint_id,
|
|
context.constant_values().GetInstId(constraint_id),
|
|
/*needs_substitution=*/false);
|
|
|
|
if (!deduction.Deduce() || !deduction.CheckDeductionIsComplete()) {
|
|
return SemIR::SpecificId::None;
|
|
}
|
|
|
|
return deduction.MakeSpecific();
|
|
}
|
|
|
|
} // namespace Carbon::Check
|