carbon-language/carbon-lang
1
0
Fork 0
mirror of https://github.com/carbon-language/carbon-lang.git synced 2026-10-06 10:54:49 +01:00
Code Issues Packages Projects Releases 10 Wiki Activity

[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/function/full_semir.carbon
Vendored
+25 -41
View File
@@ -71,19 +71,14 @@ fn F() {
// CHECK:STDOUT: %F.type: type = fn_type @F [concrete]
// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
// CHECK:STDOUT: %F: %F.type = struct_value () [concrete]
// CHECK:STDOUT: %.c5d: type = cpp_overload_set_type @As.Convert [concrete]
// CHECK:STDOUT: %empty_struct: %.c5d = struct_value () [concrete]
// CHECK:STDOUT: %int_1.5b8: Core.IntLiteral = int_value 1 [concrete]
// CHECK:STDOUT: %int_16: Core.IntLiteral = int_value 16 [concrete]
// CHECK:STDOUT: %Int.type: type = generic_class_type @Int [concrete]
// CHECK:STDOUT: %Int.generic: %Int.type = struct_value () [concrete]
// CHECK:STDOUT: %N: Core.IntLiteral = bind_symbolic_name N, 0 [symbolic]
// CHECK:STDOUT: %i16: type = class_type @Int, @Int(%int_16) [concrete]
// CHECK:STDOUT: %pattern_type.2f8: type = pattern_type %i16 [concrete]
// CHECK:STDOUT: %foo.type: type = fn_type @foo [concrete]
// CHECK:STDOUT: %foo: %foo.type = struct_value () [concrete]
// CHECK:STDOUT: %ptr.251: type = ptr_type %i16 [concrete]
// CHECK:STDOUT: %pattern_type.54c: type = pattern_type %ptr.251 [concrete]
// CHECK:STDOUT: %foo__carbon_thunk.type: type = fn_type @foo__carbon_thunk [concrete]
// CHECK:STDOUT: %foo__carbon_thunk: %foo__carbon_thunk.type = struct_value () [concrete]
// CHECK:STDOUT: %int_1.5b8: Core.IntLiteral = int_value 1 [concrete]
// CHECK:STDOUT: %As.type.90f: type = generic_interface_type @As [concrete]
// CHECK:STDOUT: %As.generic: %As.type.90f = struct_value () [concrete]
// CHECK:STDOUT: %As.type.359: type = facet_type <@As, @As(%i16)> [concrete]
@@ -100,6 +95,10 @@ fn F() {
// CHECK:STDOUT: %Core.IntLiteral.as.As.impl.Convert.specific_fn: <specific function> = specific_function %Core.IntLiteral.as.As.impl.Convert.3d5, @Core.IntLiteral.as.As.impl.Convert(%int_16) [concrete]
// CHECK:STDOUT: %bound_method.0a7: <bound method> = bound_method %int_1.5b8, %Core.IntLiteral.as.As.impl.Convert.specific_fn [concrete]
// CHECK:STDOUT: %int_1.f90: %i16 = int_value 1 [concrete]
// CHECK:STDOUT: %ptr.251: type = ptr_type %i16 [concrete]
// CHECK:STDOUT: %pattern_type.54c: type = pattern_type %ptr.251 [concrete]
// CHECK:STDOUT: %foo__carbon_thunk.type: type = fn_type @foo__carbon_thunk [concrete]
// CHECK:STDOUT: %foo__carbon_thunk: %foo__carbon_thunk.type = struct_value () [concrete]
// CHECK:STDOUT: %Copy.type: type = facet_type <@Copy> [concrete]
// CHECK:STDOUT: %Copy.Op.type: type = fn_type @Copy.Op [concrete]
// CHECK:STDOUT: %Int.as.Copy.impl.Op.type.857: type = fn_type @Int.as.Copy.impl.Op, @Int.as.Copy.impl(%N) [symbolic]
@@ -128,21 +127,14 @@ fn F() {
// CHECK:STDOUT: import Core//prelude/...
// CHECK:STDOUT: }
// CHECK:STDOUT: %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
// CHECK:STDOUT: .foo = %foo.decl
// CHECK:STDOUT: .foo = %.a21
// CHECK:STDOUT: import Cpp//...
// CHECK:STDOUT: }
// CHECK:STDOUT: %.a21: %.c5d = cpp_overload_set_value @As.Convert [concrete = constants.%empty_struct]
// CHECK:STDOUT: %Core.Int: %Int.type = import_ref Core//prelude/parts/int, Int, loaded [concrete = constants.%Int.generic]
// CHECK:STDOUT: %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
// CHECK:STDOUT: %a.patt: %pattern_type.2f8 = binding_pattern a [concrete]
// CHECK:STDOUT: %a.param_patt: %pattern_type.2f8 = value_param_pattern %a.patt, call_param0 [concrete]
// CHECK:STDOUT: } {
// CHECK:STDOUT: %a.param: %i16 = value_param call_param0
// CHECK:STDOUT: %.1: type = splice_block %i16 [concrete = constants.%i16] {
// CHECK:STDOUT: %int_16: Core.IntLiteral = int_value 16 [concrete = constants.%int_16]
// CHECK:STDOUT: %i16: type = class_type @Int, @Int(constants.%int_16) [concrete = constants.%i16]
// CHECK:STDOUT: }
// CHECK:STDOUT: %a: %i16 = bind_name a, %a.param
// CHECK:STDOUT: }
// CHECK:STDOUT: %Core.As: %As.type.90f = import_ref Core//prelude/parts/as, As, loaded [concrete = constants.%As.generic]
// CHECK:STDOUT: %Core.import_ref.52c: @Core.IntLiteral.as.As.impl.%Core.IntLiteral.as.As.impl.Convert.type (%Core.IntLiteral.as.As.impl.Convert.type.676) = import_ref Core//prelude/parts/int, loc32_39, loaded [symbolic = @Core.IntLiteral.as.As.impl.%Core.IntLiteral.as.As.impl.Convert (constants.%Core.IntLiteral.as.As.impl.Convert.086)]
// CHECK:STDOUT: %As.impl_witness_table.3fe = impl_witness_table (%Core.import_ref.52c), @Core.IntLiteral.as.As.impl [concrete]
// CHECK:STDOUT: %foo__carbon_thunk.decl: %foo__carbon_thunk.type = fn_decl @foo__carbon_thunk [concrete = constants.%foo__carbon_thunk] {
// CHECK:STDOUT: %a.patt: %pattern_type.54c = binding_pattern a [concrete]
// CHECK:STDOUT: %a.param_patt: %pattern_type.54c = value_param_pattern %a.patt, call_param0 [concrete]
@@ -154,9 +146,6 @@ fn F() {
// CHECK:STDOUT: }
// CHECK:STDOUT: %a: %ptr.251 = bind_name a, %a.param
// CHECK:STDOUT: }
// CHECK:STDOUT: %Core.As: %As.type.90f = import_ref Core//prelude/parts/as, As, loaded [concrete = constants.%As.generic]
// CHECK:STDOUT: %Core.import_ref.52c: @Core.IntLiteral.as.As.impl.%Core.IntLiteral.as.As.impl.Convert.type (%Core.IntLiteral.as.As.impl.Convert.type.676) = import_ref Core//prelude/parts/int, loc32_39, loaded [symbolic = @Core.IntLiteral.as.As.impl.%Core.IntLiteral.as.As.impl.Convert (constants.%Core.IntLiteral.as.As.impl.Convert.086)]
// CHECK:STDOUT: %As.impl_witness_table.3fe = impl_witness_table (%Core.import_ref.52c), @Core.IntLiteral.as.As.impl [concrete]
// CHECK:STDOUT: %Core.Copy: type = import_ref Core//prelude/parts/copy, Copy, loaded [concrete = constants.%Copy.type]
// CHECK:STDOUT: %Core.import_ref.b3c: @Int.as.Copy.impl.%Int.as.Copy.impl.Op.type (%Int.as.Copy.impl.Op.type.857) = import_ref Core//prelude/parts/int, loc17_31, loaded [symbolic = @Int.as.Copy.impl.%Int.as.Copy.impl.Op (constants.%Int.as.Copy.impl.Op.6aa)]
// CHECK:STDOUT: %Copy.impl_witness_table.f59 = impl_witness_table (%Core.import_ref.b3c), @Int.as.Copy.impl [concrete]
@@ -179,7 +168,7 @@ fn F() {
// CHECK:STDOUT: fn @F() {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
// CHECK:STDOUT: %foo.ref: %.c5d = name_ref foo, imports.%.a21 [concrete = constants.%empty_struct]
// CHECK:STDOUT: %int_1: Core.IntLiteral = int_value 1 [concrete = constants.%int_1.5b8]
// CHECK:STDOUT: %int_16: Core.IntLiteral = int_value 16 [concrete = constants.%int_16]
// CHECK:STDOUT: %i16: type = class_type @Int, @Int(constants.%int_16) [concrete = constants.%i16]
@@ -217,6 +206,9 @@ fn F() {
// CHECK:STDOUT: %F.type: type = fn_type @F [concrete]
// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
// CHECK:STDOUT: %F: %F.type = struct_value () [concrete]
// CHECK:STDOUT: %.c5d: type = cpp_overload_set_type @foo [concrete]
// CHECK:STDOUT: %empty_struct: %.c5d = struct_value () [concrete]
// CHECK:STDOUT: %int_1.5b8: Core.IntLiteral = int_value 1 [concrete]
// CHECK:STDOUT: %int_32: Core.IntLiteral = int_value 32 [concrete]
// CHECK:STDOUT: %Int.type: type = generic_class_type @Int [concrete]
// CHECK:STDOUT: %Int.generic: %Int.type = struct_value () [concrete]
@@ -224,7 +216,6 @@ fn F() {
// CHECK:STDOUT: %pattern_type.7ce: type = pattern_type %i32 [concrete]
// CHECK:STDOUT: %foo.type: type = fn_type @foo [concrete]
// CHECK:STDOUT: %foo: %foo.type = struct_value () [concrete]
// CHECK:STDOUT: %int_1.5b8: Core.IntLiteral = int_value 1 [concrete]
// CHECK:STDOUT: %ImplicitAs.type.cc7: type = generic_interface_type @ImplicitAs [concrete]
// CHECK:STDOUT: %ImplicitAs.generic: %ImplicitAs.type.cc7 = struct_value () [concrete]
// CHECK:STDOUT: %ImplicitAs.type.e8c: type = facet_type <@ImplicitAs, @ImplicitAs(%i32)> [concrete]
@@ -251,9 +242,10 @@ fn F() {
// CHECK:STDOUT: import Core//prelude/...
// CHECK:STDOUT: }
// CHECK:STDOUT: %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
// CHECK:STDOUT: .foo = %foo.decl
// CHECK:STDOUT: .foo = %.a21
// CHECK:STDOUT: import Cpp//...
// CHECK:STDOUT: }
// CHECK:STDOUT: %.a21: %.c5d = cpp_overload_set_value @foo [concrete = constants.%empty_struct]
// CHECK:STDOUT: %Core.Int: %Int.type = import_ref Core//prelude/parts/int, Int, loaded [concrete = constants.%Int.generic]
// CHECK:STDOUT: %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
// CHECK:STDOUT: %a.patt: %pattern_type.7ce = binding_pattern a [concrete]
@@ -287,7 +279,7 @@ fn F() {
// CHECK:STDOUT: fn @F() {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
// CHECK:STDOUT: %foo.ref: %.c5d = name_ref foo, imports.%.a21 [concrete = constants.%empty_struct]
// CHECK:STDOUT: %int_1: Core.IntLiteral = int_value 1 [concrete = constants.%int_1.5b8]
// CHECK:STDOUT: %impl.elem0: %.7ea = impl_witness_access constants.%ImplicitAs.impl_witness.acc, element0 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.592]
// CHECK:STDOUT: %bound_method.loc7_11.1: <bound method> = bound_method %int_1, %impl.elem0 [concrete = constants.%Core.IntLiteral.as.ImplicitAs.impl.Convert.bound]
@@ -296,7 +288,7 @@ fn F() {
// CHECK:STDOUT: %Core.IntLiteral.as.ImplicitAs.impl.Convert.call: init %i32 = call %bound_method.loc7_11.2(%int_1) [concrete = constants.%int_1.5d2]
// CHECK:STDOUT: %.loc7_11.1: %i32 = value_of_initializer %Core.IntLiteral.as.ImplicitAs.impl.Convert.call [concrete = constants.%int_1.5d2]
// CHECK:STDOUT: %.loc7_11.2: %i32 = converted %int_1, %.loc7_11.1 [concrete = constants.%int_1.5d2]
// CHECK:STDOUT: %foo.call: init %empty_tuple.type = call %foo.ref(%.loc7_11.2)
// CHECK:STDOUT: %foo.call: init %empty_tuple.type = call imports.%foo.decl(%.loc7_11.2)
// CHECK:STDOUT: return
// CHECK:STDOUT: }
// CHECK:STDOUT:
@@ -313,8 +305,8 @@ fn F() {
// CHECK:STDOUT: %Int.generic: %Int.type = struct_value () [concrete]
// CHECK:STDOUT: %i16: type = class_type @Int, @Int(%int_16) [concrete]
// CHECK:STDOUT: %pattern_type.2f8: type = pattern_type %i16 [concrete]
// CHECK:STDOUT: %foo_short.type: type = fn_type @foo_short [concrete]
// CHECK:STDOUT: %foo_short: %foo_short.type = struct_value () [concrete]
// CHECK:STDOUT: %.f28: type = cpp_overload_set_type @foo_short [concrete]
// CHECK:STDOUT: %empty_struct: %.f28 = struct_value () [concrete]
// CHECK:STDOUT: %ptr: type = ptr_type %i16 [concrete]
// CHECK:STDOUT: %pattern_type.54c: type = pattern_type %ptr [concrete]
// CHECK:STDOUT: %foo_short__carbon_thunk.type: type = fn_type @foo_short__carbon_thunk [concrete]
@@ -328,19 +320,11 @@ fn F() {
// CHECK:STDOUT: import Core//prelude/...
// CHECK:STDOUT: }
// CHECK:STDOUT: %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
// CHECK:STDOUT: .foo_short = %foo_short.decl
// CHECK:STDOUT: .foo_short = %.3be
// CHECK:STDOUT: import Cpp//...
// CHECK:STDOUT: }
// CHECK:STDOUT: %Core.Int: %Int.type = import_ref Core//prelude/parts/int, Int, loaded [concrete = constants.%Int.generic]
// CHECK:STDOUT: %foo_short.decl: %foo_short.type = fn_decl @foo_short [concrete = constants.%foo_short] {
// CHECK:STDOUT: %return.patt: %pattern_type.2f8 = return_slot_pattern [concrete]
// CHECK:STDOUT: %return.param_patt: %pattern_type.2f8 = out_param_pattern %return.patt, call_param0 [concrete]
// CHECK:STDOUT: } {
// CHECK:STDOUT: %int_16: Core.IntLiteral = int_value 16 [concrete = constants.%int_16]
// CHECK:STDOUT: %i16: type = class_type @Int, @Int(constants.%int_16) [concrete = constants.%i16]
// CHECK:STDOUT: %return.param: ref %i16 = out_param call_param0
// CHECK:STDOUT: %return: ref %i16 = return_slot %return.param
// CHECK:STDOUT: }
// CHECK:STDOUT: %.3be: %.f28 = cpp_overload_set_value @foo_short [concrete = constants.%empty_struct]
// CHECK:STDOUT: %foo_short__carbon_thunk.decl: %foo_short__carbon_thunk.type = fn_decl @foo_short__carbon_thunk [concrete = constants.%foo_short__carbon_thunk] {
// CHECK:STDOUT: %return.patt: %pattern_type.54c = binding_pattern r#return [concrete]
// CHECK:STDOUT: %return.param_patt: %pattern_type.54c = value_param_pattern %return.patt, call_param0 [concrete]
@@ -373,7 +357,7 @@ fn F() {
// CHECK:STDOUT: %x.patt: %pattern_type.2f8 = binding_pattern x [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT: %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %foo_short.ref: %foo_short.type = name_ref foo_short, imports.%foo_short.decl [concrete = constants.%foo_short]
// CHECK:STDOUT: %foo_short.ref: %.f28 = name_ref foo_short, imports.%.3be [concrete = constants.%empty_struct]
// CHECK:STDOUT: %.loc7_30.1: ref %i16 = temporary_storage
// CHECK:STDOUT: %addr: %ptr = addr_of %.loc7_30.1
// CHECK:STDOUT: %foo_short__carbon_thunk.call: init %empty_tuple.type = call imports.%foo_short__carbon_thunk.decl(%addr)