Files
carbon-lang/toolchain/check/impl.h
T
5abe5a3c21 Stop allowing impl redeclarations to differ syntactically in where clause (#4850)
Based on [the lastest thinking on
#4672](https://github.com/carbon-language/carbon-lang/issues/4672#issuecomment-2606209281)
, require a full syntactic match for impl redeclaration, instead of
excluding the `where` restriction. This means no updates to the impl
witness on redeclaration, and no diagnostics that those updates are
consistent.

Not included in this PR, but will need to be done in the future:
* Support for assigning values to associated constants in the body of
the impl definition. This will require moving the checking that
non-function associated constants are set from the definition start to
definition end.
* Identify semantic redeclarations that are not syntactic matches to
give a failed redeclaration diagnostic. This should be done once we are
already identifying impl declarations with the same type structure in
order to require they be identified in an impl_priority/match_first
block.
* Merging of the functions in `check/impl.cpp` that are now always
called together.

Also add some test coverage of `where` parsing I developed in PR I've
now abandoned because of this new simplification of the impl
redeclaration semantics.

---------

Co-authored-by: Josh L <josh11b@users.noreply.github.com>
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
2025-01-28 06:00:34 +00:00

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// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#ifndef CARBON_TOOLCHAIN_CHECK_IMPL_H_
#define CARBON_TOOLCHAIN_CHECK_IMPL_H_
#include "toolchain/check/context.h"
#include "toolchain/sem_ir/ids.h"
namespace Carbon::Check {
// Returns the initial witness value for a new impl declaration.
auto ImplWitnessForDeclaration(Context& context, const SemIR::Impl& impl)
-> SemIR::InstId;
auto AddConstantsToImplWitnessFromConstraint(Context& context,
const SemIR::Impl& impl,
SemIR::InstId witness_id) -> void;
// Update `impl`'s witness at the start of a definition.
auto ImplWitnessStartDefinition(Context& context, SemIR::Impl& impl) -> void;
// Adds the function members to the witness for `impl`.
auto FinishImplWitness(Context& context, SemIR::Impl& impl) -> void;
// Sets all unset members of the witness for `impl` to the error instruction.
auto FillImplWitnessWithErrors(Context& context, SemIR::Impl& impl) -> void;
} // namespace Carbon::Check
#endif // CARBON_TOOLCHAIN_CHECK_IMPL_H_