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carbon-lang/toolchain/check/testdata/interop/cpp/impls/copy.carbon
T
372f632d9d Implement support for copying C++ classes. (#6434)
When performing impl lookup for `Core.Copy` for a C++ class type, look
for a copy constructor. If we find one, synthesize an impl witness that
calls the constructor.

This adds initial support for impl lookup to delegate to the C++ interop
logic for queries involving C++ types. For now, we don't implement the
rules from #6166 that compare a synthesized type structure for the C++
impl against the best Carbon type structure, but the framework for
building that support is established here.

Currently there is no caching of the lookup here, and we build unique
`ImplWitnessTable`s for each lookup, which leads to each impl lookup
producing a distinct facet value. This results in some errors in generic
contexts; this will be addressed in follow-up changes. This PR aims only
to support the non-generic case.

---------

Co-authored-by: Dana Jansens <danakj@orodu.net>
Co-authored-by: Carbon Infra Bot <carbon-external-infra@google.com>
2025-12-02 02:52:23 +00:00

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// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/convert.carbon
//
// AUTOUPDATE
// TIP: To test this file alone, run:
// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/interop/cpp/impls/copy.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/interop/cpp/impls/copy.carbon
// --- types.h
class Copyable {
public:
Copyable(const Copyable&);
};
class ExplicitCopy {
public:
explicit ExplicitCopy(const ExplicitCopy&);
};
class DeletedCopy {
public:
DeletedCopy(const DeletedCopy&) = delete;
};
class MoveOnly {
public:
MoveOnly(MoveOnly&&);
};
class DeletedMove {
public:
DeletedMove(DeletedMove&&) = delete;
};
class NonConstCopy {
public:
NonConstCopy(NonConstCopy&);
};
class AmbiguousCopy {
public:
AmbiguousCopy(const AmbiguousCopy&, int = 0);
AmbiguousCopy(const AmbiguousCopy&, char = 0);
};
class PrivateCopy {
private:
PrivateCopy(const PrivateCopy&);
};
class ProtectedCopy {
protected:
ProtectedCopy(const ProtectedCopy&);
};
// --- copy_copyable.carbon
library "[[@TEST_NAME]]";
import Cpp library "types.h";
fn CopyCopyable(c: Cpp.Copyable) -> Cpp.Copyable {
//@dump-sem-ir-begin
return c;
//@dump-sem-ir-end
}
fn CopyExplicitCopy(c: Cpp.ExplicitCopy) -> Cpp.ExplicitCopy {
//@dump-sem-ir-begin
return c;
//@dump-sem-ir-end
}
// --- fail_copy_noncopyable.carbon
library "[[@TEST_NAME]]";
import Cpp library "types.h";
fn CopyDeletedCopy(c: Cpp.DeletedCopy) -> Cpp.DeletedCopy {
// CHECK:STDERR: fail_copy_noncopyable.carbon:[[@LINE+8]]:10: error: attempt to use a deleted function [CppInteropParseError]
// CHECK:STDERR: 15 | return c;
// CHECK:STDERR: | ^
// CHECK:STDERR: fail_copy_noncopyable.carbon:[[@LINE-6]]:10: in file included here [InCppInclude]
// CHECK:STDERR: ./types.h:14:3: note: 'DeletedCopy' has been explicitly marked deleted here [CppInteropParseNote]
// CHECK:STDERR: 14 | DeletedCopy(const DeletedCopy&) = delete;
// CHECK:STDERR: | ^
// CHECK:STDERR:
return c;
}
fn CopyMoveOnly(c: Cpp.MoveOnly) -> Cpp.MoveOnly {
// CHECK:STDERR: fail_copy_noncopyable.carbon:[[@LINE+8]]:10: error: attempt to use a deleted function [CppInteropParseError]
// CHECK:STDERR: 27 | return c;
// CHECK:STDERR: | ^
// CHECK:STDERR: fail_copy_noncopyable.carbon:[[@LINE-18]]:10: in file included here [InCppInclude]
// CHECK:STDERR: ./types.h:19:3: note: copy constructor is implicitly deleted because 'MoveOnly' has a user-declared move constructor [CppInteropParseNote]
// CHECK:STDERR: 19 | MoveOnly(MoveOnly&&);
// CHECK:STDERR: | ^
// CHECK:STDERR:
return c;
}
fn CopyDeletedMove(c: Cpp.DeletedMove) -> Cpp.DeletedMove {
// CHECK:STDERR: fail_copy_noncopyable.carbon:[[@LINE+8]]:10: error: attempt to use a deleted function [CppInteropParseError]
// CHECK:STDERR: 39 | return c;
// CHECK:STDERR: | ^
// CHECK:STDERR: fail_copy_noncopyable.carbon:[[@LINE-30]]:10: in file included here [InCppInclude]
// CHECK:STDERR: ./types.h:24:3: note: copy constructor is implicitly deleted because 'DeletedMove' has a user-declared move constructor [CppInteropParseNote]
// CHECK:STDERR: 24 | DeletedMove(DeletedMove&&) = delete;
// CHECK:STDERR: | ^
// CHECK:STDERR:
return c;
}
fn CopyNonConstCopy(c: Cpp.NonConstCopy) -> Cpp.NonConstCopy {
// TODO: List candidates here.
// CHECK:STDERR: fail_copy_noncopyable.carbon:[[@LINE+7]]:10: error: cannot copy value of type `Cpp.NonConstCopy` [CopyOfUncopyableType]
// CHECK:STDERR: return c;
// CHECK:STDERR: ^
// CHECK:STDERR: fail_copy_noncopyable.carbon:[[@LINE+4]]:10: note: type `Cpp.NonConstCopy` does not implement interface `Core.Copy` [MissingImplInMemberAccessNote]
// CHECK:STDERR: return c;
// CHECK:STDERR: ^
// CHECK:STDERR:
return c;
}
fn CopyAmbiguousCopy(c: Cpp.AmbiguousCopy) -> Cpp.AmbiguousCopy {
// TODO: List candidates here.
// CHECK:STDERR: fail_copy_noncopyable.carbon:[[@LINE+7]]:10: error: cannot copy value of type `Cpp.AmbiguousCopy` [CopyOfUncopyableType]
// CHECK:STDERR: return c;
// CHECK:STDERR: ^
// CHECK:STDERR: fail_copy_noncopyable.carbon:[[@LINE+4]]:10: note: type `Cpp.AmbiguousCopy` does not implement interface `Core.Copy` [MissingImplInMemberAccessNote]
// CHECK:STDERR: return c;
// CHECK:STDERR: ^
// CHECK:STDERR:
return c;
}
fn CopyPrivateCopy(c: Cpp.PrivateCopy) -> Cpp.PrivateCopy {
// TODO: Note is missing location.
// CHECK:STDERR: fail_copy_noncopyable.carbon:[[@LINE+5]]:10: error: cannot access private member `PrivateCopy` of type `Cpp.PrivateCopy` [ClassInvalidMemberAccess]
// CHECK:STDERR: return c;
// CHECK:STDERR: ^
// CHECK:STDERR: fail_copy_noncopyable.carbon: note: declared here [ClassMemberDeclaration]
// CHECK:STDERR:
return c;
}
fn CopyProtectedCopy(c: Cpp.ProtectedCopy) -> Cpp.ProtectedCopy {
// TODO: Note is missing location.
// CHECK:STDERR: fail_copy_noncopyable.carbon:[[@LINE+5]]:10: error: cannot access protected member `ProtectedCopy` of type `Cpp.ProtectedCopy` [ClassInvalidMemberAccess]
// CHECK:STDERR: return c;
// CHECK:STDERR: ^
// CHECK:STDERR: fail_copy_noncopyable.carbon: note: declared here [ClassMemberDeclaration]
// CHECK:STDERR:
return c;
}
// --- fail_todo_copy_generically.carbon
library "[[@TEST_NAME]]";
import Cpp library "types.h";
fn Copy[T:! Core.Copy](c: T) -> T {
return c;
}
fn DoCopy(c: Cpp.Copyable) -> Cpp.Copyable {
// TODO: We perform multiple impl lookups for `Cpp.Copyable as Core.Copy`
// here, and each one produces a different impl witness, resulting in a
// deduction failure.
// CHECK:STDERR: fail_todo_copy_generically.carbon:[[@LINE+7]]:10: error: inconsistent deductions for value of generic parameter `T` [DeductionInconsistent]
// CHECK:STDERR: return Copy(c);
// CHECK:STDERR: ^~~~~~~
// CHECK:STDERR: fail_todo_copy_generically.carbon:[[@LINE-11]]:1: note: while deducing parameters of generic declared here [DeductionGenericHere]
// CHECK:STDERR: fn Copy[T:! Core.Copy](c: T) -> T {
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
return Copy(c);
}
class Wrap(T:! Core.Copy) {}
// TODO: This should type-check: each conversion of `Cpp.Copyable` to
// `Core.Copy` should produce the same value.
fn EqualWitnesses(p: Wrap(Cpp.Copyable)*) -> Wrap(Cpp.Copyable)* {
// CHECK:STDERR: fail_todo_copy_generically.carbon:[[@LINE+7]]:3: error: cannot implicitly convert expression of type `Wrap(Cpp.Copyable as Core.Copy)*` to `Wrap(Cpp.Copyable as Core.Copy)*` [ConversionFailure]
// CHECK:STDERR: return p;
// CHECK:STDERR: ^~~~~~~~~
// CHECK:STDERR: fail_todo_copy_generically.carbon:[[@LINE+4]]:3: note: type `Wrap(Cpp.Copyable as Core.Copy)*` does not implement interface `Core.ImplicitAs(Wrap(Cpp.Copyable as Core.Copy)*)` [MissingImplInMemberAccessNote]
// CHECK:STDERR: return p;
// CHECK:STDERR: ^~~~~~~~~
// CHECK:STDERR:
return p;
}
// CHECK:STDOUT: --- copy_copyable.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
// CHECK:STDOUT: %Copyable: type = class_type @Copyable [concrete]
// CHECK:STDOUT: %Copy.type: type = facet_type <@Copy> [concrete]
// CHECK:STDOUT: %Copy.Op.type: type = fn_type @Copy.Op [concrete]
// CHECK:STDOUT: %Copyable.Copyable.type: type = fn_type @Copyable.Copyable [concrete]
// CHECK:STDOUT: %Copyable.Copyable: %Copyable.Copyable.type = struct_value () [concrete]
// CHECK:STDOUT: %const.622: type = const_type %Copyable [concrete]
// CHECK:STDOUT: %ptr.29d: type = ptr_type %const.622 [concrete]
// CHECK:STDOUT: %ptr.e47: type = ptr_type %Copyable [concrete]
// CHECK:STDOUT: %Copyable__carbon_thunk.type: type = fn_type @Copyable__carbon_thunk [concrete]
// CHECK:STDOUT: %Copyable__carbon_thunk: %Copyable__carbon_thunk.type = struct_value () [concrete]
// CHECK:STDOUT: %impl_witness.65e: <witness> = impl_witness @CopyCopyable.%impl_witness_table [concrete]
// CHECK:STDOUT: %Copy.facet.26f: %Copy.type = facet_value %Copyable, (%impl_witness.65e) [concrete]
// CHECK:STDOUT: %Copyable.Op.type: type = fn_type @Copyable.Op [concrete]
// CHECK:STDOUT: %Copyable.Op: %Copyable.Op.type = struct_value () [concrete]
// CHECK:STDOUT: %.667: type = fn_type_with_self_type %Copy.Op.type, %Copy.facet.26f [concrete]
// CHECK:STDOUT: %ExplicitCopy: type = class_type @ExplicitCopy [concrete]
// CHECK:STDOUT: %ExplicitCopy.ExplicitCopy.type: type = fn_type @ExplicitCopy.ExplicitCopy [concrete]
// CHECK:STDOUT: %ExplicitCopy.ExplicitCopy: %ExplicitCopy.ExplicitCopy.type = struct_value () [concrete]
// CHECK:STDOUT: %const.d8d: type = const_type %ExplicitCopy [concrete]
// CHECK:STDOUT: %ptr.093: type = ptr_type %const.d8d [concrete]
// CHECK:STDOUT: %ptr.84c: type = ptr_type %ExplicitCopy [concrete]
// CHECK:STDOUT: %ExplicitCopy__carbon_thunk.type: type = fn_type @ExplicitCopy__carbon_thunk [concrete]
// CHECK:STDOUT: %ExplicitCopy__carbon_thunk: %ExplicitCopy__carbon_thunk.type = struct_value () [concrete]
// CHECK:STDOUT: %impl_witness.215: <witness> = impl_witness @CopyExplicitCopy.%impl_witness_table [concrete]
// CHECK:STDOUT: %Copy.facet.cfa: %Copy.type = facet_value %ExplicitCopy, (%impl_witness.215) [concrete]
// CHECK:STDOUT: %ExplicitCopy.Op.type: type = fn_type @ExplicitCopy.Op [concrete]
// CHECK:STDOUT: %ExplicitCopy.Op: %ExplicitCopy.Op.type = struct_value () [concrete]
// CHECK:STDOUT: %.a87: type = fn_type_with_self_type %Copy.Op.type, %Copy.facet.cfa [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: imports {
// CHECK:STDOUT: %Copyable.Copyable.decl: %Copyable.Copyable.type = fn_decl @Copyable.Copyable [concrete = constants.%Copyable.Copyable] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: %Copyable__carbon_thunk.decl: %Copyable__carbon_thunk.type = fn_decl @Copyable__carbon_thunk [concrete = constants.%Copyable__carbon_thunk] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: %ExplicitCopy.ExplicitCopy.decl: %ExplicitCopy.ExplicitCopy.type = fn_decl @ExplicitCopy.ExplicitCopy [concrete = constants.%ExplicitCopy.ExplicitCopy] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: %ExplicitCopy__carbon_thunk.decl: %ExplicitCopy__carbon_thunk.type = fn_decl @ExplicitCopy__carbon_thunk [concrete = constants.%ExplicitCopy__carbon_thunk] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: fn @CopyCopyable(%c.param: %Copyable) -> %return.param: %Copyable {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: %c.ref: %Copyable = name_ref c, %c
// CHECK:STDOUT: %impl_witness_table = impl_witness_table (%Copyable.Op.decl), invalid [concrete]
// CHECK:STDOUT: %impl_witness: <witness> = impl_witness %impl_witness_table [concrete = constants.%impl_witness.65e]
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %impl.elem0: %.667 = impl_witness_access constants.%impl_witness.65e, element0 [concrete = constants.%Copyable.Op]
// CHECK:STDOUT: %bound_method: <bound method> = bound_method %c.ref, %impl.elem0
// CHECK:STDOUT: %.loc8_10.1: ref %Copyable = temporary_storage
// CHECK:STDOUT: %Op.ref: %Copyable.Copyable.type = name_ref Op, imports.%Copyable.Copyable.decl [concrete = constants.%Copyable.Copyable]
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %.loc8_10.2: ref %Copyable = value_as_ref %c.ref
// CHECK:STDOUT: %addr.loc8_10.1: %ptr.e47 = addr_of %.loc8_10.2
// CHECK:STDOUT: %.loc8_10.3: %ptr.29d = as_compatible %addr.loc8_10.1
// CHECK:STDOUT: %.loc8_10.4: %ptr.29d = converted %addr.loc8_10.1, %.loc8_10.3
// CHECK:STDOUT: %addr.loc8_10.2: %ptr.e47 = addr_of %.loc6_34
// CHECK:STDOUT: %Copyable__carbon_thunk.call: init %empty_tuple.type = call imports.%Copyable__carbon_thunk.decl(%.loc8_10.4, %addr.loc8_10.2)
// CHECK:STDOUT: %.loc8_10.5: init %Copyable = in_place_init %Copyable__carbon_thunk.call, %.loc6_34
// CHECK:STDOUT: return %.loc8_10.5 to %return
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: fn @CopyExplicitCopy(%c.param: %ExplicitCopy) -> %return.param: %ExplicitCopy {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: %c.ref: %ExplicitCopy = name_ref c, %c
// CHECK:STDOUT: %impl_witness_table = impl_witness_table (%ExplicitCopy.Op.decl), invalid [concrete]
// CHECK:STDOUT: %impl_witness: <witness> = impl_witness %impl_witness_table [concrete = constants.%impl_witness.215]
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %impl.elem0: %.a87 = impl_witness_access constants.%impl_witness.215, element0 [concrete = constants.%ExplicitCopy.Op]
// CHECK:STDOUT: %bound_method: <bound method> = bound_method %c.ref, %impl.elem0
// CHECK:STDOUT: %.loc14_10.1: ref %ExplicitCopy = temporary_storage
// CHECK:STDOUT: %Op.ref: %ExplicitCopy.ExplicitCopy.type = name_ref Op, imports.%ExplicitCopy.ExplicitCopy.decl [concrete = constants.%ExplicitCopy.ExplicitCopy]
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: %.loc14_10.2: ref %ExplicitCopy = value_as_ref %c.ref
// CHECK:STDOUT: %addr.loc14_10.1: %ptr.84c = addr_of %.loc14_10.2
// CHECK:STDOUT: %.loc14_10.3: %ptr.093 = as_compatible %addr.loc14_10.1
// CHECK:STDOUT: %.loc14_10.4: %ptr.093 = converted %addr.loc14_10.1, %.loc14_10.3
// CHECK:STDOUT: %addr.loc14_10.2: %ptr.84c = addr_of %.loc12_42
// CHECK:STDOUT: %ExplicitCopy__carbon_thunk.call: init %empty_tuple.type = call imports.%ExplicitCopy__carbon_thunk.decl(%.loc14_10.4, %addr.loc14_10.2)
// CHECK:STDOUT: %.loc14_10.5: init %ExplicitCopy = in_place_init %ExplicitCopy__carbon_thunk.call, %.loc12_42
// CHECK:STDOUT: return %.loc14_10.5 to %return
// CHECK:STDOUT: }
// CHECK:STDOUT: