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[Carbon/C++ interop] Add support for C++ overloaded functions (#5891)

Browse Source 
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
This commit is contained in:
Ivana Ivanovska
2025-09-15 12:29:49 +00:00
committed by GitHub
parent 20ac6b9270
commit 12ddfb9c7c
61 changed files with 4633 additions and 2252 deletions
Download Patch File Download Diff File Expand all files Collapse all files
toolchain/check/testdata/interop/cpp/enum/anonymous.carbon
Vendored
+48 -54
View File
@@ -10,6 +10,8 @@
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/interop/cpp/enum/anonymous.carbon
// TODO: Tests marked as `fail_todo_5891_` to fixed as a follow-up of https://github.com/carbon-language/carbon-lang/pull/5891.
// --- anon.h
enum { a, b, c };
@@ -23,7 +25,7 @@ class C {
void F(decltype(d));
};
// --- copy_enum.carbon
// --- fail_todo_5891_copy_enum.carbon
library "[[@TEST_NAME]]";
@@ -33,36 +35,41 @@ import Cpp library "anon.h";
fn G() {
Cpp.F(Cpp.b);
// CHECK:STDERR: fail_todo_5891_copy_enum.carbon:[[@LINE+5]]:3: error: missing object argument in method call [MissingObjectInMethodCall]
// CHECK:STDERR: Cpp.C.C().F(Cpp.C.e);
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_todo_5891_copy_enum.carbon: note: calling function declared here [InCallToFunction]
// CHECK:STDERR:
Cpp.C.C().F(Cpp.C.e);
}
//@dump-sem-ir-end
// CHECK:STDOUT: --- copy_enum.carbon
// CHECK:STDOUT: --- fail_todo_5891_copy_enum.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %G.type: type = fn_type @G [concrete]
// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
// CHECK:STDOUT: %G: %G.type = struct_value () [concrete]
// CHECK:STDOUT: %.4f0: type = class_type @.1 [concrete]
// CHECK:STDOUT: %F.type: type = fn_type @F [concrete]
// CHECK:STDOUT: %F: %F.type = struct_value () [concrete]
// CHECK:STDOUT: %.557: type = cpp_overload_set_type @C.C [concrete]
// CHECK:STDOUT: %empty_struct.56a: %.557 = struct_value () [concrete]
// CHECK:STDOUT: %int_1.81a: %.4f0 = int_value 1 [concrete]
// CHECK:STDOUT: %ptr.793: type = ptr_type %.4f0 [concrete]
// CHECK:STDOUT: %F__carbon_thunk.type.eda1ac.1: type = fn_type @F__carbon_thunk.1 [concrete]
// CHECK:STDOUT: %F__carbon_thunk.0cd6a8.1: %F__carbon_thunk.type.eda1ac.1 = struct_value () [concrete]
// CHECK:STDOUT: %int_1.81a: %.4f0 = int_value 1 [concrete]
// CHECK:STDOUT: %C: type = class_type @C [concrete]
// CHECK:STDOUT: %C.C.type: type = fn_type @C.C [concrete]
// CHECK:STDOUT: %C.C: %C.C.type = struct_value () [concrete]
// CHECK:STDOUT: %.d40: type = cpp_overload_set_type @C__carbon_thunk [concrete]
// CHECK:STDOUT: %empty_struct.e73: %.d40 = struct_value () [concrete]
// CHECK:STDOUT: %ptr.d9e: type = ptr_type %C [concrete]
// CHECK:STDOUT: %C__carbon_thunk.type: type = fn_type @C__carbon_thunk [concrete]
// CHECK:STDOUT: %C__carbon_thunk: %C__carbon_thunk.type = struct_value () [concrete]
// CHECK:STDOUT: %.bb7: type = class_type @.2 [concrete]
// CHECK:STDOUT: %C.F.type: type = fn_type @C.F [concrete]
// CHECK:STDOUT: %C.F: %C.F.type = struct_value () [concrete]
// CHECK:STDOUT: %.9a3: type = cpp_overload_set_type @C.F [concrete]
// CHECK:STDOUT: %empty_struct.acc: %.9a3 = struct_value () [concrete]
// CHECK:STDOUT: %int_1.1d6: %.bb7 = int_value 1 [concrete]
// CHECK:STDOUT: %ptr.73d: type = ptr_type %.bb7 [concrete]
// CHECK:STDOUT: %F__carbon_thunk.type.eda1ac.2: type = fn_type @F__carbon_thunk.2 [concrete]
// CHECK:STDOUT: %F__carbon_thunk.0cd6a8.2: %F__carbon_thunk.type.eda1ac.2 = struct_value () [concrete]
// CHECK:STDOUT: %int_1.1d6: %.bb7 = int_value 1 [concrete]
// CHECK:STDOUT: %T.as.Destroy.impl.Op.type.bf8: type = fn_type @T.as.Destroy.impl.Op, @T.as.Destroy.impl(%.bb7) [concrete]
// CHECK:STDOUT: %T.as.Destroy.impl.Op.823: %T.as.Destroy.impl.Op.type.bf8 = struct_value () [concrete]
// CHECK:STDOUT: %T.as.Destroy.impl.Op.type.140: type = fn_type @T.as.Destroy.impl.Op, @T.as.Destroy.impl(%C) [concrete]
@@ -73,44 +80,32 @@ fn G() {
// CHECK:STDOUT:
// CHECK:STDOUT: imports {
// CHECK:STDOUT: %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
// CHECK:STDOUT: .F = %F.decl
// CHECK:STDOUT: .F = %.4a9
// CHECK:STDOUT: .b = %int_1.81a
// CHECK:STDOUT: .C = %C.decl
// CHECK:STDOUT: import Cpp//...
// CHECK:STDOUT: }
// CHECK:STDOUT: %F.decl: %F.type = fn_decl @F [concrete = constants.%F] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: %.4a9: %.557 = cpp_overload_set_value @C.C [concrete = constants.%empty_struct.56a]
// CHECK:STDOUT: %int_1.81a: %.4f0 = int_value 1 [concrete = constants.%int_1.81a]
// CHECK:STDOUT: %F__carbon_thunk.decl.e1b8ec.1: %F__carbon_thunk.type.eda1ac.1 = fn_decl @F__carbon_thunk.1 [concrete = constants.%F__carbon_thunk.0cd6a8.1] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: %int_1.81a: %.4f0 = int_value 1 [concrete = constants.%int_1.81a]
// CHECK:STDOUT: %C.decl: type = class_decl @C [concrete = constants.%C] {} {}
// CHECK:STDOUT: %C.C.decl: %C.C.type = fn_decl @C.C [concrete = constants.%C.C] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: %.40b: %.d40 = cpp_overload_set_value @C__carbon_thunk [concrete = constants.%empty_struct.e73]
// CHECK:STDOUT: %C__carbon_thunk.decl: %C__carbon_thunk.type = fn_decl @C__carbon_thunk [concrete = constants.%C__carbon_thunk] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: %C.F.decl: %C.F.type = fn_decl @C.F [concrete = constants.%C.F] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: %.951: %.9a3 = cpp_overload_set_value @C.F [concrete = constants.%empty_struct.acc]
// CHECK:STDOUT: %int_1.1d6: %.bb7 = int_value 1 [concrete = constants.%int_1.1d6]
// CHECK:STDOUT: %F__carbon_thunk.decl.e1b8ec.2: %F__carbon_thunk.type.eda1ac.2 = fn_decl @F__carbon_thunk.2 [concrete = constants.%F__carbon_thunk.0cd6a8.2] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: %int_1.1d6: %.bb7 = int_value 1 [concrete = constants.%int_1.1d6]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: file {
@@ -120,41 +115,40 @@ fn G() {
// CHECK:STDOUT: fn @G() {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: %Cpp.ref.loc8_3: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %F.ref.loc8: %F.type = name_ref F, imports.%F.decl [concrete = constants.%F]
// CHECK:STDOUT: %F.ref.loc8: %.557 = name_ref F, imports.%.4a9 [concrete = constants.%empty_struct.56a]
// CHECK:STDOUT: %Cpp.ref.loc8_9: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %b.ref: %.4f0 = name_ref b, imports.%int_1.81a [concrete = constants.%int_1.81a]
// CHECK:STDOUT: %.loc8_12.1: ref %.4f0 = temporary_storage
// CHECK:STDOUT: %.loc8_12.2: ref %.4f0 = temporary %.loc8_12.1, %b.ref
// CHECK:STDOUT: %addr.loc8_14: %ptr.793 = addr_of %.loc8_12.2
// CHECK:STDOUT: %F__carbon_thunk.call.loc8: init %empty_tuple.type = call imports.%F__carbon_thunk.decl.e1b8ec.1(%addr.loc8_14)
// CHECK:STDOUT: %Cpp.ref.loc10_3: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %C.ref.loc10_6: type = name_ref C, imports.%C.decl [concrete = constants.%C]
// CHECK:STDOUT: %C.ref.loc10_8: %C.C.type = name_ref C, imports.%C.C.decl [concrete = constants.%C.C]
// CHECK:STDOUT: %.loc10_11.1: ref %C = temporary_storage
// CHECK:STDOUT: %addr.loc10_11.1: %ptr.d9e = addr_of %.loc10_11.1
// CHECK:STDOUT: %C__carbon_thunk.call: init %empty_tuple.type = call imports.%C__carbon_thunk.decl(%addr.loc10_11.1)
// CHECK:STDOUT: %.loc10_11.2: init %C = in_place_init %C__carbon_thunk.call, %.loc10_11.1
// CHECK:STDOUT: %.loc10_11.3: ref %C = temporary %.loc10_11.1, %.loc10_11.2
// CHECK:STDOUT: %F.ref.loc10: %C.F.type = name_ref F, imports.%C.F.decl [concrete = constants.%C.F]
// CHECK:STDOUT: %C.F.bound: <bound method> = bound_method %.loc10_11.3, %F.ref.loc10
// CHECK:STDOUT: %Cpp.ref.loc10_15: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %C.ref.loc10_18: type = name_ref C, imports.%C.decl [concrete = constants.%C]
// CHECK:STDOUT: %Cpp.ref.loc15_3: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %C.ref.loc15_6: type = name_ref C, imports.%C.decl [concrete = constants.%C]
// CHECK:STDOUT: %C.ref.loc15_8: %.d40 = name_ref C, imports.%.40b [concrete = constants.%empty_struct.e73]
// CHECK:STDOUT: %.loc15_11.1: ref %C = temporary_storage
// CHECK:STDOUT: %addr.loc15_11.1: %ptr.d9e = addr_of %.loc15_11.1
// CHECK:STDOUT: %C__carbon_thunk.call: init %empty_tuple.type = call imports.%C__carbon_thunk.decl(%addr.loc15_11.1)
// CHECK:STDOUT: %.loc15_11.2: init %C = in_place_init %C__carbon_thunk.call, %.loc15_11.1
// CHECK:STDOUT: %.loc15_11.3: ref %C = temporary %.loc15_11.1, %.loc15_11.2
// CHECK:STDOUT: %F.ref.loc15: %.9a3 = name_ref F, imports.%.951 [concrete = constants.%empty_struct.acc]
// CHECK:STDOUT: %Cpp.ref.loc15_15: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %C.ref.loc15_18: type = name_ref C, imports.%C.decl [concrete = constants.%C]
// CHECK:STDOUT: %e.ref: %.bb7 = name_ref e, imports.%int_1.1d6 [concrete = constants.%int_1.1d6]
// CHECK:STDOUT: %addr.loc10_11.2: %ptr.d9e = addr_of %.loc10_11.3
// CHECK:STDOUT: %.loc10_20.1: ref %.bb7 = temporary_storage
// CHECK:STDOUT: %.loc10_20.2: ref %.bb7 = temporary %.loc10_20.1, %e.ref
// CHECK:STDOUT: %addr.loc10_22: %ptr.73d = addr_of %.loc10_20.2
// CHECK:STDOUT: %F__carbon_thunk.call.loc10: init %empty_tuple.type = call imports.%F__carbon_thunk.decl.e1b8ec.2(%addr.loc10_11.2, %addr.loc10_22)
// CHECK:STDOUT: %T.as.Destroy.impl.Op.bound.loc10_20: <bound method> = bound_method %.loc10_20.2, constants.%T.as.Destroy.impl.Op.823
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %bound_method.loc10_20: <bound method> = bound_method %.loc10_20.2, %T.as.Destroy.impl.Op.specific_fn.1
// CHECK:STDOUT: %addr.loc10_20: %ptr.73d = addr_of %.loc10_20.2
// CHECK:STDOUT: %T.as.Destroy.impl.Op.call.loc10_20: init %empty_tuple.type = call %bound_method.loc10_20(%addr.loc10_20)
// CHECK:STDOUT: %T.as.Destroy.impl.Op.bound.loc10_11: <bound method> = bound_method %.loc10_11.3, constants.%T.as.Destroy.impl.Op.d4e
// CHECK:STDOUT: %.loc15_20.1: ref %.bb7 = temporary_storage
// CHECK:STDOUT: %.loc15_20.2: ref %.bb7 = temporary %.loc15_20.1, %e.ref
// CHECK:STDOUT: %addr.loc15_22: %ptr.73d = addr_of %.loc15_20.2
// CHECK:STDOUT: %F__carbon_thunk.call.loc15: init %empty_tuple.type = call imports.%F__carbon_thunk.decl.e1b8ec.2(<error>, %addr.loc15_22)
// CHECK:STDOUT: %T.as.Destroy.impl.Op.bound.loc15_20: <bound method> = bound_method %.loc15_20.2, constants.%T.as.Destroy.impl.Op.823
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %bound_method.loc10_11: <bound method> = bound_method %.loc10_11.3, %T.as.Destroy.impl.Op.specific_fn.2
// CHECK:STDOUT: %addr.loc10_11.3: %ptr.d9e = addr_of %.loc10_11.3
// CHECK:STDOUT: %T.as.Destroy.impl.Op.call.loc10_11: init %empty_tuple.type = call %bound_method.loc10_11(%addr.loc10_11.3)
// CHECK:STDOUT: %bound_method.loc15_20: <bound method> = bound_method %.loc15_20.2, %T.as.Destroy.impl.Op.specific_fn.1
// CHECK:STDOUT: %addr.loc15_20: %ptr.73d = addr_of %.loc15_20.2
// CHECK:STDOUT: %T.as.Destroy.impl.Op.call.loc15_20: init %empty_tuple.type = call %bound_method.loc15_20(%addr.loc15_20)
// CHECK:STDOUT: %T.as.Destroy.impl.Op.bound.loc15_11: <bound method> = bound_method %.loc15_11.3, constants.%T.as.Destroy.impl.Op.d4e
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %bound_method.loc15_11: <bound method> = bound_method %.loc15_11.3, %T.as.Destroy.impl.Op.specific_fn.2
// CHECK:STDOUT: %addr.loc15_11.2: %ptr.d9e = addr_of %.loc15_11.3
// CHECK:STDOUT: %T.as.Destroy.impl.Op.call.loc15_11: init %empty_tuple.type = call %bound_method.loc15_11(%addr.loc15_11.2)
// CHECK:STDOUT: %T.as.Destroy.impl.Op.bound.loc8: <bound method> = bound_method %.loc8_12.2, constants.%T.as.Destroy.impl.Op.8db
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %bound_method.loc8: <bound method> = bound_method %.loc8_12.2, %T.as.Destroy.impl.Op.specific_fn.3