Files
carbon-lang/toolchain/check/testdata/interop/cpp/enum/convert.carbon
T
Chandler CarruthandChristopher Di Bella 8a59f2a76b Fix mangling collision for C++ class template specializations (#7269)
Carbon-side thunks (for example the `Copy`/`Destroy` witness thunks
generated for imported C++ types) are mangled by Carbon, and their names
incorporate a fingerprint of the involved types. The instruction
fingerprinter identifies a class only by its name and parent scope,
which is sufficient for Carbon classes but not for imported C++ classes:
different specializations of one class template (and other cases such as
types in anonymous namespaces) share a Carbon name and parent scope. As
a result, the thunks for two distinct specializations could mangle to
the same name, producing a single LLVM function with two definitions and
failing `verifyModule` during lowering.

When fingerprinting a class imported from C++, also include the Clang
mangled name of its type.

Test: toolchain/lower/testdata/interop/cpp/thunks.carbon gains a split
with two specializations of one class template, each requiring a thunk;
their thunks now get distinct mangled names instead of colliding.

Assisted-by: Claude Code

---------

Co-authored-by: Christopher Di Bella <cjdb.ns@gmail.com>
2026-05-30 08:13:00 +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/int.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/enum/convert.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/interop/cpp/enum/convert.carbon
// --- enum.h
enum Enum : short { a, b, c };
enum Other : short {};
enum DifferentSize : long {};
// --- convert_enum.carbon
library "[[@TEST_NAME]]";
import Cpp library "enum.h";
//@dump-sem-ir-begin
fn F() {
let unused a: i16 = Cpp.Enum.a as i16;
let unused b: Cpp.Enum = (42 as i16) as Cpp.Enum;
let unused c: Cpp.Other = Cpp.a as Cpp.Other;
}
//@dump-sem-ir-end
// --- fail_wrong_type.carbon
library "[[@TEST_NAME]]";
import Cpp library "enum.h";
fn F() {
// CHECK:STDERR: fail_wrong_type.carbon:[[@LINE+7]]:3: error: cannot convert expression of type `Cpp.Enum` to `i8` with `as` [ConversionFailure]
// CHECK:STDERR: Cpp.Enum.a as i8;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_wrong_type.carbon:[[@LINE+4]]:3: note: type `Cpp.Enum` does not implement interface `Core.As(i8)` [MissingImplInMemberAccessInContext]
// CHECK:STDERR: Cpp.Enum.a as i8;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~
// CHECK:STDERR:
Cpp.Enum.a as i8;
// CHECK:STDERR: fail_wrong_type.carbon:[[@LINE+7]]:3: error: cannot convert expression of type `Cpp.Enum` to `i32` with `as` [ConversionFailure]
// CHECK:STDERR: Cpp.Enum.a as i32;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_wrong_type.carbon:[[@LINE+4]]:3: note: type `Cpp.Enum` does not implement interface `Core.As(i32)` [MissingImplInMemberAccessInContext]
// CHECK:STDERR: Cpp.Enum.a as i32;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~
// CHECK:STDERR:
Cpp.Enum.a as i32;
// CHECK:STDERR: fail_wrong_type.carbon:[[@LINE+7]]:3: error: cannot convert expression of type `i8` to `Cpp.Enum` with `as` [ConversionFailure]
// CHECK:STDERR: (42 as i8) as Cpp.Enum;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_wrong_type.carbon:[[@LINE+4]]:3: note: type `i8` does not implement interface `Core.As(Cpp.Enum)` [MissingImplInMemberAccessInContext]
// CHECK:STDERR: (42 as i8) as Cpp.Enum;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
(42 as i8) as Cpp.Enum;
// CHECK:STDERR: fail_wrong_type.carbon:[[@LINE+7]]:3: error: cannot convert expression of type `i32` to `Cpp.Enum` with `as` [ConversionFailure]
// CHECK:STDERR: (42 as i32) as Cpp.Enum;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_wrong_type.carbon:[[@LINE+4]]:3: note: type `i32` does not implement interface `Core.As(Cpp.Enum)` [MissingImplInMemberAccessInContext]
// CHECK:STDERR: (42 as i32) as Cpp.Enum;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
(42 as i32) as Cpp.Enum;
// CHECK:STDERR: fail_wrong_type.carbon:[[@LINE+7]]:3: error: cannot convert expression of type `Cpp.Enum` to `Cpp.DifferentSize` with `as` [ConversionFailure]
// CHECK:STDERR: Cpp.a as Cpp.DifferentSize;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR: fail_wrong_type.carbon:[[@LINE+4]]:3: note: type `Cpp.Enum` does not implement interface `Core.As(Cpp.DifferentSize)` [MissingImplInMemberAccessInContext]
// CHECK:STDERR: Cpp.a as Cpp.DifferentSize;
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
Cpp.a as Cpp.DifferentSize;
}
// CHECK:STDOUT: --- convert_enum.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %F.type: type = fn_type @F [concrete]
// CHECK:STDOUT: %F: %F.type = struct_value () [concrete]
// CHECK:STDOUT: %int_16: Core.IntLiteral = int_value 16 [concrete]
// CHECK:STDOUT: %i16: type = class_type @Int, @Int(%int_16) [concrete]
// CHECK:STDOUT: %pattern_type.0cb: type = pattern_type %i16 [concrete]
// CHECK:STDOUT: %Enum: type = class_type @Enum [concrete]
// CHECK:STDOUT: %int_0.167: %Enum = int_value 0 [concrete]
// CHECK:STDOUT: %int_0.713: %i16 = int_value 0 [concrete]
// CHECK:STDOUT: %pattern_type.361: type = pattern_type %Enum [concrete]
// CHECK:STDOUT: %int_42.20e: Core.IntLiteral = int_value 42 [concrete]
// CHECK:STDOUT: %As.type.457: type = facet_type <@As, @As(%i16)> [concrete]
// CHECK:STDOUT: %To: Core.IntLiteral = symbolic_binding To, 0 [symbolic]
// CHECK:STDOUT: %Core.IntLiteral.as.As.impl.Convert.type.fc5: type = fn_type @Core.IntLiteral.as.As.impl.Convert, @Core.IntLiteral.as.As.impl(%To) [symbolic]
// CHECK:STDOUT: %Core.IntLiteral.as.As.impl.Convert.3a8: %Core.IntLiteral.as.As.impl.Convert.type.fc5 = struct_value () [symbolic]
// CHECK:STDOUT: %As.impl_witness.bca: <witness> = impl_witness imports.%As.impl_witness_table.2e6, @Core.IntLiteral.as.As.impl(%int_16) [concrete]
// CHECK:STDOUT: %Core.IntLiteral.as.As.impl.Convert.type.36d: type = fn_type @Core.IntLiteral.as.As.impl.Convert, @Core.IntLiteral.as.As.impl(%int_16) [concrete]
// CHECK:STDOUT: %Core.IntLiteral.as.As.impl.Convert.036: %Core.IntLiteral.as.As.impl.Convert.type.36d = struct_value () [concrete]
// CHECK:STDOUT: %As.facet: %As.type.457 = facet_value Core.IntLiteral, (%As.impl_witness.bca) [concrete]
// CHECK:STDOUT: %As.WithSelf.Convert.type.9f1: type = fn_type @As.WithSelf.Convert, @As.WithSelf(%i16, %As.facet) [concrete]
// CHECK:STDOUT: %.3ca: type = fn_type_with_self_type %As.WithSelf.Convert.type.9f1, %As.facet [concrete]
// CHECK:STDOUT: %Core.IntLiteral.as.As.impl.Convert.bound: <bound method> = bound_method %int_42.20e, %Core.IntLiteral.as.As.impl.Convert.036 [concrete]
// CHECK:STDOUT: %Core.IntLiteral.as.As.impl.Convert.specific_fn: <specific function> = specific_function %Core.IntLiteral.as.As.impl.Convert.036, @Core.IntLiteral.as.As.impl.Convert(%int_16) [concrete]
// CHECK:STDOUT: %bound_method: <bound method> = bound_method %int_42.20e, %Core.IntLiteral.as.As.impl.Convert.specific_fn [concrete]
// CHECK:STDOUT: %int_42.50d: %i16 = int_value 42 [concrete]
// CHECK:STDOUT: %int_42.3d1: %Enum = int_value 42 [concrete]
// CHECK:STDOUT: %Other: type = class_type @Other [concrete]
// CHECK:STDOUT: %pattern_type.7cb: type = pattern_type %Other [concrete]
// CHECK:STDOUT: %int_0.10c: %Other = int_value 0 [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: imports {
// CHECK:STDOUT: %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
// CHECK:STDOUT: .Enum = %Enum.decl
// CHECK:STDOUT: .Other = %Other.decl
// CHECK:STDOUT: .a = %int_0
// CHECK:STDOUT: import Cpp//...
// CHECK:STDOUT: }
// CHECK:STDOUT: %Enum.decl: type = class_decl @Enum [concrete = constants.%Enum] {} {}
// CHECK:STDOUT: %int_0: %Enum = int_value 0 [concrete = constants.%int_0.167]
// CHECK:STDOUT: %Core.import_ref.6c4: @Core.IntLiteral.as.As.impl.%Core.IntLiteral.as.As.impl.Convert.type (%Core.IntLiteral.as.As.impl.Convert.type.fc5) = import_ref Core//prelude/parts/int, loc{{\d+_\d+}}, loaded [symbolic = @Core.IntLiteral.as.As.impl.%Core.IntLiteral.as.As.impl.Convert (constants.%Core.IntLiteral.as.As.impl.Convert.3a8)]
// CHECK:STDOUT: %As.impl_witness_table.2e6 = impl_witness_table (%Core.import_ref.6c4), @Core.IntLiteral.as.As.impl [concrete]
// CHECK:STDOUT: %Other.decl: type = class_decl @Other [concrete = constants.%Other] {} {}
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: file {
// CHECK:STDOUT: %F.decl: %F.type = fn_decl @F [concrete = constants.%F] {} {}
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: fn @F() {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: name_binding_decl {
// CHECK:STDOUT: %a.patt: %pattern_type.0cb = value_binding_pattern a [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT: %Cpp.ref.loc8: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %Enum.ref.loc8: type = name_ref Enum, imports.%Enum.decl [concrete = constants.%Enum]
// CHECK:STDOUT: %a.ref.loc8: %Enum = name_ref a, imports.%int_0 [concrete = constants.%int_0.167]
// CHECK:STDOUT: %i16.loc8_37: type = type_literal constants.%i16 [concrete = constants.%i16]
// CHECK:STDOUT: %.loc8_34.1: %i16 = as_compatible %a.ref.loc8 [concrete = constants.%int_0.713]
// CHECK:STDOUT: %.loc8_34.2: %i16 = converted %a.ref.loc8, %.loc8_34.1 [concrete = constants.%int_0.713]
// CHECK:STDOUT: %i16.loc8_17: type = type_literal constants.%i16 [concrete = constants.%i16]
// CHECK:STDOUT: %a: %i16 = value_binding a, %.loc8_34.2
// CHECK:STDOUT: name_binding_decl {
// CHECK:STDOUT: %b.patt: %pattern_type.361 = value_binding_pattern b [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT: %int_42: Core.IntLiteral = int_value 42 [concrete = constants.%int_42.20e]
// CHECK:STDOUT: %i16.loc9: type = type_literal constants.%i16 [concrete = constants.%i16]
// CHECK:STDOUT: %impl.elem0: %.3ca = impl_witness_access constants.%As.impl_witness.bca, element0 [concrete = constants.%Core.IntLiteral.as.As.impl.Convert.036]
// CHECK:STDOUT: %bound_method.loc9_32.1: <bound method> = bound_method %int_42, %impl.elem0 [concrete = constants.%Core.IntLiteral.as.As.impl.Convert.bound]
// CHECK:STDOUT: %specific_fn: <specific function> = specific_function %impl.elem0, @Core.IntLiteral.as.As.impl.Convert(constants.%int_16) [concrete = constants.%Core.IntLiteral.as.As.impl.Convert.specific_fn]
// CHECK:STDOUT: %bound_method.loc9_32.2: <bound method> = bound_method %int_42, %specific_fn [concrete = constants.%bound_method]
// CHECK:STDOUT: %Core.IntLiteral.as.As.impl.Convert.call: init %i16 = call %bound_method.loc9_32.2(%int_42) [concrete = constants.%int_42.50d]
// CHECK:STDOUT: %.loc9_32.1: %i16 = value_of_initializer %Core.IntLiteral.as.As.impl.Convert.call [concrete = constants.%int_42.50d]
// CHECK:STDOUT: %.loc9_32.2: %i16 = converted %int_42, %.loc9_32.1 [concrete = constants.%int_42.50d]
// CHECK:STDOUT: %Cpp.ref.loc9_43: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %Enum.ref.loc9_46: type = name_ref Enum, imports.%Enum.decl [concrete = constants.%Enum]
// CHECK:STDOUT: %.loc9_40.1: %Enum = as_compatible %.loc9_32.2 [concrete = constants.%int_42.3d1]
// CHECK:STDOUT: %.loc9_40.2: %Enum = converted %.loc9_32.2, %.loc9_40.1 [concrete = constants.%int_42.3d1]
// CHECK:STDOUT: %.loc9_20: type = splice_block %Enum.ref.loc9_20 [concrete = constants.%Enum] {
// CHECK:STDOUT: %Cpp.ref.loc9_17: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %Enum.ref.loc9_20: type = name_ref Enum, imports.%Enum.decl [concrete = constants.%Enum]
// CHECK:STDOUT: }
// CHECK:STDOUT: %b: %Enum = value_binding b, %.loc9_40.2
// CHECK:STDOUT: name_binding_decl {
// CHECK:STDOUT: %c.patt: %pattern_type.7cb = value_binding_pattern c [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT: %Cpp.ref.loc10_29: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %a.ref.loc10: %Enum = name_ref a, imports.%int_0 [concrete = constants.%int_0.167]
// CHECK:STDOUT: %Cpp.ref.loc10_38: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %Other.ref.loc10_41: type = name_ref Other, imports.%Other.decl [concrete = constants.%Other]
// CHECK:STDOUT: %.loc10_35.1: %Other = as_compatible %a.ref.loc10 [concrete = constants.%int_0.10c]
// CHECK:STDOUT: %.loc10_35.2: %Other = converted %a.ref.loc10, %.loc10_35.1 [concrete = constants.%int_0.10c]
// CHECK:STDOUT: %.loc10_20: type = splice_block %Other.ref.loc10_20 [concrete = constants.%Other] {
// CHECK:STDOUT: %Cpp.ref.loc10_17: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: %Other.ref.loc10_20: type = name_ref Other, imports.%Other.decl [concrete = constants.%Other]
// CHECK:STDOUT: }
// CHECK:STDOUT: %c: %Other = value_binding c, %.loc10_35.2
// CHECK:STDOUT: return
// CHECK:STDOUT: }
// CHECK:STDOUT: