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https://github.com/carbon-language/carbon-lang.git
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Jon Ross-Perkins
b34e349792
This delays the conversion of `query_self_const_id` until the actual witness creation, mainly so that users of `BuildCustomWitness` don't need to do extra work to ensure `GetFacetAsType` logic is shared/applied. This is coming up for destroy logic.
47 lines
2.3 KiB
C++
47 lines
2.3 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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#ifndef CARBON_TOOLCHAIN_CHECK_CPP_IMPL_LOOKUP_H_
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#define CARBON_TOOLCHAIN_CHECK_CPP_IMPL_LOOKUP_H_
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#include "toolchain/check/context.h"
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#include "toolchain/check/custom_witness.h"
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#include "toolchain/check/impl_lookup.h"
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#include "toolchain/check/type_structure.h"
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#include "toolchain/sem_ir/ids.h"
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#include "toolchain/sem_ir/specific_interface.h"
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namespace Carbon::Check {
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// Performs lookup for an impl witness for a query involving C++ types. Returns
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// a witness value, or `None` if a synthesized C++ witness should not be used.
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//
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// Given a known `core_interface`, we can synthesize a witness based on C++
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// operator overloads or special member functions. Performs the suitable C++
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// lookup to determine if this interface should be considered implemented for
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// the specified type, and if so, synthesizes and returns a suitable witness.
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//
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// `best_impl_type_structure` provides the type structure of the best-matching
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// impl declaration. If this is better than every viable C++ candidate, a "none"
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// result will be returned. If this is worse than the best viable C++ candidate
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// according to C++ rules, a witness for the C++ candidate will be returned.
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// Otherwise, it is at least as good as the best viable C++ candidate, but there
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// is some C++ candidate that has a better type structure, in which case the
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// result is ambiguous and we diagnose an error. This parameter can be null if
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// there is no usable impl for this query.
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//
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// `best_impl_loc_id` gives the location of the impl corresponding to the best
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// type structure, and can be `None` if `best_impl_type_structure` is null. This
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// parameter is used only for ambiguity diagnostics.
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auto LookupCppImpl(Context& context, SemIR::LocId loc_id,
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CoreInterface core_interface,
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SemIR::ConstantId query_self_const_id,
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SemIR::SpecificInterface specific_interface,
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const TypeStructure* best_impl_type_structure,
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SemIR::LocId best_impl_loc_id) -> SemIR::InstId;
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} // namespace Carbon::Check
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#endif // CARBON_TOOLCHAIN_CHECK_CPP_IMPL_LOOKUP_H_
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