mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 22:02:23 +01:00
Ivana Ivanovska
12ddfb9c7c
As proposed in [Carbon: C++ interop for overloaded functions and function templates](https://docs.google.com/document/d/1KUxumZtNe3mY3TsjW2s_ZADOlAaFlrtsLKHVILtqIaM/edit?tab=t.0), Clang is used to perform the overload resolution using C++ rules, when an overloaded C++ set is called from Carbon. Once a function is selected, it's converted into a Carbon function and called using the Carbon rules including argument conversions. A single non-templated function is treated the same way as an overload set and the same rules apply for its call. Template functions are not supported yet. Demo: a) Non-templated function calls: ```c++ // --- overloads.h auto foo(int a, short b) -> void; auto foo(double a) -> void; auto foo(int a) -> void; ``` ```c++ // overloads.cpp #include "overloads.h" #include <cstdio> auto foo(int a, short b) -> void { printf("hello from foo_int_short(%d, %d) \n", a, b); } auto foo(double a) -> void { printf("hello from foo_double(%f) \n", a); } auto foo(int a) -> void { printf("hello from foo_int(%d) \n", a); } ``` ```c++ library "Main"; import Cpp library "overloads.h"; fn Run() -> i32 { Cpp.foo(1.1 as f64); return 0; } ``` ``` $ clang -c overloads.cpp $ bazel-bin/toolchain/carbon compile main.carbon $ bazel-bin/toolchain/carbon link overloads.o main.o --output=demo $ ./demo hello from foo_double(1.100000) ``` b) Constructors: ```c++ // --- constructor_overloads.h class C { public: C(); C(int a, int b); }; ``` ```c++ // constructor_overloads.cpp #include "constructor_overloads.h" #include <cstdio> C::C() { printf("hello from C() \n"); } C::C(int a, int b) { printf("hello from C(%d, %d) \n", a, b); } ``` ```c++ library "Main"; import Cpp library "constructor_overloads.h"; fn Run() -> i32 { let c1: Cpp.C = Cpp.C.C(); let c2: Cpp.C = Cpp.C.C(1, 2); return 0; } ``` ``` $ clang -c constructor_overloads.cpp $ bazel-bin/toolchain/carbon compile main.carbon $ bazel-bin/toolchain/carbon link constructor_overloads.o main.o \--output=demo $ ./demo hello from C() hello from C(1, 2) ``` Follow-ups: - `Cpp.foo({})` - proper handling of struct literals as call args. - Fix access for overloaded sets. - Fix tests: - Method calls: `error: missing object argument in method call [MissingObjectInMethodCall]` in tests. - Fix `toolchain/check/testdata/interop/cpp/import.carbon` test. - Fix `enums` support. - Fix `str` -> `std::string_view` mapping. Part of #5915
39 lines
1.2 KiB
C++
39 lines
1.2 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_SEM_IR_CPP_OVERLOAD_SET_H_
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#define CARBON_TOOLCHAIN_SEM_IR_CPP_OVERLOAD_SET_H_
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#include "clang/AST/Decl.h"
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#include "clang/AST/UnresolvedSet.h"
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#include "common/ostream.h"
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#include "toolchain/base/value_store.h"
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#include "toolchain/sem_ir/ids.h"
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namespace Carbon::SemIR {
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// An overloaded C++ function.
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struct CppOverloadSet : public Printable<CppOverloadSet> {
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// The function's name.
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NameId name_id;
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// The parent scope.
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NameScopeId parent_scope_id;
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// List of all named decls found at name lookup.
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// TODO: Find a good small size for the UnresolvedSet<size> or rework how we
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// store the candidates.
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clang::UnresolvedSet<4> candidate_functions;
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auto Print(llvm::raw_ostream& out) const -> void {
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out << "name: " << name_id << ", parent_scope: " << parent_scope_id;
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}
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};
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using CppOverloadSetStore = ValueStore<CppOverloadSetId, CppOverloadSet>;
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} // namespace Carbon::SemIR
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#endif // CARBON_TOOLCHAIN_SEM_IR_CPP_OVERLOAD_SET_H_
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