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Import C++ vtables (#7174)

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This correctly renders the vtable in SemIR, including allowing overrides
in
Carbon-derived-from-C++ classes.

It doesn't work in lowering because clang walks the methods of the
CXXRecordDecl - and we currently don't export anything into the
CXXRecordDecl's methods (we do export the fields) - so that's next.

This also doesn't teach Clang to affirmatively emit the vtable
regardless of the types use in C++ code - or to have Carbon use the
vtable in an object's initialization.
This commit is contained in:
David Blaikie
2026-05-11 17:33:08 +00:00
committed by GitHub
parent 0f5de499d6
commit df8b25522e
8 changed files with 508 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files
toolchain/check/testdata/interop/cpp/class/import/abstract.carbon
Vendored
+27 -5
View File
@@ -38,7 +38,7 @@ class C {
extend base: Cpp.A;
}
// --- fail_todo_impl_abstract_member.carbon
// --- impl_abstract_member.carbon
library "[[@TEST_NAME]]";
@@ -46,13 +46,24 @@ import Cpp library "abstract.h";
class C {
extend base: Cpp.A;
// CHECK:STDERR: fail_todo_impl_abstract_member.carbon:[[@LINE+4]]:3: error: override without compatible virtual in base class [OverrideWithoutVirtualInBase]
// CHECK:STDERR: override fn f[unused ref self: Self]() {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
override fn f[unused ref self: Self]() {}
}
// --- fail_impl_mismatch_member.carbon
library "[[@TEST_NAME]]";
import Cpp library "abstract.h";
class C {
extend base: Cpp.A;
// CHECK:STDERR: fail_impl_mismatch_member.carbon:[[@LINE+4]]:3: error: override without compatible virtual in base class [OverrideWithoutVirtualInBase]
// CHECK:STDERR: override fn invalid[unused ref self: Self]() {}
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// CHECK:STDERR:
override fn invalid[unused ref self: Self]() {}
}
// --- abstract_final.h
// C++ allows a class to be both abstract and final.
@@ -98,6 +109,8 @@ fn F() -> Cpp.AbstractFinal {
// CHECK:STDOUT: %pattern_type: type = pattern_type %AbstractFinal [concrete]
// CHECK:STDOUT: %F.type: type = fn_type @F [concrete]
// CHECK:STDOUT: %F: %F.type = struct_value () [concrete]
// CHECK:STDOUT: %AbstractFinal.f.type: type = fn_type @AbstractFinal.f [concrete]
// CHECK:STDOUT: %AbstractFinal.f: %AbstractFinal.f.type = struct_value () [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: imports {
@@ -106,6 +119,11 @@ fn F() -> Cpp.AbstractFinal {
// CHECK:STDOUT: import Cpp//...
// CHECK:STDOUT: }
// CHECK:STDOUT: %AbstractFinal.decl: type = class_decl @AbstractFinal [concrete = constants.%AbstractFinal] {} {}
// CHECK:STDOUT: %AbstractFinal.f.decl: %AbstractFinal.f.type = fn_decl @AbstractFinal.f [concrete = constants.%AbstractFinal.f] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: file {
@@ -121,6 +139,10 @@ fn F() -> Cpp.AbstractFinal {
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: vtable @AbstractFinal.vtable {
// CHECK:STDOUT: imports.%AbstractFinal.f.decl
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: fn @F() -> out %return.param: %AbstractFinal {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: %F.ref: %F.type = name_ref F, file.%F.decl [concrete = constants.%F]
toolchain/check/testdata/interop/cpp/class/import/class.carbon
Vendored
+7 -3
View File
@@ -486,10 +486,10 @@ fn GenericUse(p2: Generic(Cpp.Class1)) {
// CHECK:STDOUT: %MyF.type: type = fn_type @MyF [concrete]
// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
// CHECK:STDOUT: %MyF: %MyF.type = struct_value () [concrete]
// CHECK:STDOUT: %Bar.f.cpp_overload_set.type: type = cpp_overload_set_type @Bar.f.cpp_overload_set [concrete]
// CHECK:STDOUT: %Bar.f.cpp_overload_set.value: %Bar.f.cpp_overload_set.type = cpp_overload_set_value @Bar.f.cpp_overload_set [concrete]
// CHECK:STDOUT: %Bar.f.type: type = fn_type @Bar.f [concrete]
// CHECK:STDOUT: %Bar.f: %Bar.f.type = struct_value () [concrete]
// CHECK:STDOUT: %Bar.f.cpp_overload_set.type: type = cpp_overload_set_type @Bar.f.cpp_overload_set [concrete]
// CHECK:STDOUT: %Bar.f.cpp_overload_set.value: %Bar.f.cpp_overload_set.type = cpp_overload_set_value @Bar.f.cpp_overload_set [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: imports {
@@ -498,12 +498,12 @@ fn GenericUse(p2: Generic(Cpp.Class1)) {
// CHECK:STDOUT: import Cpp//...
// CHECK:STDOUT: }
// CHECK:STDOUT: %Bar.decl: type = class_decl @Bar [concrete = constants.%Bar] {} {}
// CHECK:STDOUT: %Bar.f.cpp_overload_set.value: %Bar.f.cpp_overload_set.type = cpp_overload_set_value @Bar.f.cpp_overload_set [concrete = constants.%Bar.f.cpp_overload_set.value]
// CHECK:STDOUT: %Bar.f.decl: %Bar.f.type = fn_decl @Bar.f [concrete = constants.%Bar.f] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: %Bar.f.cpp_overload_set.value: %Bar.f.cpp_overload_set.type = cpp_overload_set_value @Bar.f.cpp_overload_set [concrete = constants.%Bar.f.cpp_overload_set.value]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: file {
@@ -521,6 +521,10 @@ fn GenericUse(p2: Generic(Cpp.Class1)) {
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: vtable @Bar.vtable {
// CHECK:STDOUT: imports.%Bar.f.decl
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: fn @MyF(%bar.param: %ptr.f68) {
// CHECK:STDOUT: !entry:
// CHECK:STDOUT: %bar.ref: %ptr.f68 = name_ref bar, %bar
toolchain/check/testdata/interop/cpp/class/import/dynamic.carbon
Vendored
+112
View File
@@ -0,0 +1,112 @@
// 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/primitives.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/class/import/dynamic.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/interop/cpp/class/import/dynamic.carbon
// --- dynamic_base_from_cpp.carbon
library "[[@TEST_NAME]]";
import Cpp;
inline Cpp '''
struct FurtherBase {
virtual auto further_base_func() -> int {
return 11;
}
};
struct Base: FurtherBase {
int i;
virtual auto func() -> int {
return 7;
}
};
auto Use(Base& b) -> int {
return b.func();
}
''';
base class Derived {
extend base: Cpp.Base;
virtual fn other_func[unused self: Self]() -> i32 {
return 3;
}
}
//@dump-sem-ir-begin
inline Cpp '''
// TODO: Carbon lowering should request clang to generate the vtable.
void WorkaroundToEmitCtorAndVtable() {
Carbon::Derived d;
}
// TODO: Carbon lowering should emit initialization that refers to the
// Clang-lowered vtable.
auto DoThing() -> int {
Carbon::Derived d;
return Use(d);
}
''';
//@dump-sem-ir-end
// CHECK:STDOUT: --- dynamic_base_from_cpp.carbon
// CHECK:STDOUT:
// CHECK:STDOUT: constants {
// CHECK:STDOUT: %Base: type = class_type @Base [concrete]
// CHECK:STDOUT: %FurtherBase.further_base_func.type: type = fn_type @FurtherBase.further_base_func [concrete]
// CHECK:STDOUT: %FurtherBase.further_base_func: %FurtherBase.further_base_func.type = struct_value () [concrete]
// CHECK:STDOUT: %Base.func.type: type = fn_type @Base.func [concrete]
// CHECK:STDOUT: %Base.func: %Base.func.type = struct_value () [concrete]
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: imports {
// CHECK:STDOUT: %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
// CHECK:STDOUT: .Base = %Base.decl
// CHECK:STDOUT: import Cpp//...
// CHECK:STDOUT: }
// CHECK:STDOUT: %Base.decl: type = class_decl @Base [concrete = constants.%Base] {} {}
// CHECK:STDOUT: %FurtherBase.further_base_func.decl: %FurtherBase.further_base_func.type = fn_decl @FurtherBase.further_base_func [concrete = constants.%FurtherBase.further_base_func] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: %Base.func.decl: %Base.func.type = fn_decl @Base.func [concrete = constants.%Base.func] {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: } {
// CHECK:STDOUT: <elided>
// CHECK:STDOUT: }
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: file {
// CHECK:STDOUT: %Cpp.ref.loc35: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
// CHECK:STDOUT: inline_cpp "\n// TODO: Carbon lowering should request clang to generate the vtable.\nvoid WorkaroundToEmitCtorAndVtable() {\n Carbon::Derived d;\n}\n\n// TODO: Carbon lowering should emit initialization that refers to the\n// Clang-lowered vtable.\nauto DoThing() -> int {\n Carbon::Derived d;\n return Use(d);\n}\n\n"
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: vtable @Base.vtable {
// CHECK:STDOUT: imports.%FurtherBase.further_base_func.decl
// CHECK:STDOUT: imports.%Base.func.decl
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: vtable @FurtherBase.vtable {
// CHECK:STDOUT: imports.%FurtherBase.further_base_func.decl
// CHECK:STDOUT: }
// CHECK:STDOUT:
// CHECK:STDOUT: vtable @Derived.vtable {
// CHECK:STDOUT: constants.%FurtherBase.further_base_func
// CHECK:STDOUT: constants.%Base.func
// CHECK:STDOUT: @Derived.%Derived.other_func.decl
// CHECK:STDOUT: }
// CHECK:STDOUT: