mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-10-01 14:55:52 +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
81 lines
2.8 KiB
Plaintext
81 lines
2.8 KiB
Plaintext
// 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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//
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// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/int.carbon
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// EXTRA-ARGS: --clang-arg=-std=c++26
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//
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// AUTOUPDATE
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// TIP: To test this file alone, run:
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// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/lower/testdata/interop/cpp/method.carbon
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// TIP: To dump output, run:
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// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/lower/testdata/interop/cpp/method.carbon
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// TODO: Tests marked as `fail_todo_5891_` to fixed as a follow-up of https://github.com/carbon-language/carbon-lang/pull/5891.
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// --- methods.h
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struct A {
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int by_val() const { return n; }
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int by_ref() { return n; }
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int n;
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};
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// --- fail_todo_5891_call_by_val.carbon
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library "[[@TEST_NAME]]";
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import Cpp library "methods.h";
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fn UseVal(a: Cpp.A) -> i32 {
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// CHECK:STDERR: fail_todo_5891_call_by_val.carbon:[[@LINE+5]]:10: error: missing object argument in method call [MissingObjectInMethodCall]
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// CHECK:STDERR: return a.by_val();
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// CHECK:STDERR: ^~~~~~~~~~
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// CHECK:STDERR: fail_todo_5891_call_by_val.carbon: note: calling function declared here [InCallToFunction]
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// CHECK:STDERR:
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return a.by_val();
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}
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// --- fail_todo_5891_call_by_ref.carbon
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library "[[@TEST_NAME]]";
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import Cpp library "methods.h";
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fn UseVal(a: Cpp.A*) -> i32 {
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// CHECK:STDERR: fail_todo_5891_call_by_ref.carbon:[[@LINE+5]]:10: error: missing object argument in method call [MissingObjectInMethodCall]
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// CHECK:STDERR: return a->by_ref();
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// CHECK:STDERR: ^~~~~~~~~~~
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// CHECK:STDERR: fail_todo_5891_call_by_ref.carbon: note: calling function declared here [InCallToFunction]
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// CHECK:STDERR:
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return a->by_ref();
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}
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// --- thunk.h
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struct NeedThunk {
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void Implicit(signed char c) const;
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void Explicit(this NeedThunk, signed char c);
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};
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// --- fail_todo_5891_call_thunk.carbon
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library "[[@TEST_NAME]]";
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import Cpp library "thunk.h";
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fn Call(n: Cpp.NeedThunk) {
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// CHECK:STDERR: fail_todo_5891_call_thunk.carbon:[[@LINE+5]]:3: error: missing object argument in method call [MissingObjectInMethodCall]
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// CHECK:STDERR: n.Implicit(1);
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// CHECK:STDERR: ^~~~~~~~~~~~~
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// CHECK:STDERR: fail_todo_5891_call_thunk.carbon: note: calling function declared here [InCallToFunction]
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// CHECK:STDERR:
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n.Implicit(1);
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// CHECK:STDERR: fail_todo_5891_call_thunk.carbon:[[@LINE+5]]:3: error: missing object argument in method call [MissingObjectInMethodCall]
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// CHECK:STDERR: n.Explicit(1);
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// CHECK:STDERR: ^~~~~~~~~~~~~
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// CHECK:STDERR: fail_todo_5891_call_thunk.carbon: note: calling function declared here [InCallToFunction]
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// CHECK:STDERR:
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n.Explicit(1);
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}
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