clang: Make the type_info builtin declaration a singleton #151277
Merged
+38
−3
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
matts1
force-pushed
the
push-sruqkvlnlwpk
branch
from
3c7dab0 to
b35918a
Compare
matts1
changed the title
matts1
commented
Jul 30, 2025
|
@atetubou FYI |
matts1
changed the title
matts1
force-pushed
the
push-sruqkvlnlwpk
branch
2 times, most recently
from
4e8387c to
47d44b2
Compare
llvmbot
added
clang
|
@llvm/pr-subscribers-clang @llvm/pr-subscribers-clang-modules Author: Matt (matts1) ChangesThis fixes an ambiguous type type_info when you try and reference the Fixes #38400 Full diff: https://github.com/llvm/llvm-project/pull/151277.diff 6 Files Affected:
diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
index 0273109f8a698..3d70654314939 100644
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -1290,6 +1290,9 @@ class ASTContext : public RefCountedBase<ASTContext> {
// Implicitly-declared type 'struct _GUID'.
mutable TagDecl *MSGuidTagDecl = nullptr;
+ // Implicitly-declared type 'struct type_info'.
+ mutable TagDecl *MSTypeInfoTagDecl = nullptr;
+
/// Keep track of CUDA/HIP device-side variables ODR-used by host code.
/// This does not include extern shared variables used by device host
/// functions as addresses of shared variables are per warp, therefore
@@ -2381,6 +2384,15 @@ class ASTContext : public RefCountedBase<ASTContext> {
return getTagDeclType(MSGuidTagDecl);
}
+ /// Retrieve the implicitly-predeclared 'struct type_info' declaration.
+ TagDecl *getMSTypeInfoTagDecl() const {
+ // Lazily create this type on demand - it's only needed for MS builds.
+ if (!MSTypeInfoTagDecl) {
+ MSTypeInfoTagDecl = buildImplicitRecord("type_info");
+ }
+ return MSTypeInfoTagDecl;
+ }
+
/// Return whether a declaration to a builtin is allowed to be
/// overloaded/redeclared.
bool canBuiltinBeRedeclared(const FunctionDecl *) const;
diff --git a/clang/include/clang/AST/DeclID.h b/clang/include/clang/AST/DeclID.h
index 384f7b031e007..47ae05b2747ae 100644
--- a/clang/include/clang/AST/DeclID.h
+++ b/clang/include/clang/AST/DeclID.h
@@ -77,6 +77,9 @@ enum PredefinedDeclIDs {
/// The internal '__NSConstantString' tag type.
PREDEF_DECL_CF_CONSTANT_STRING_TAG_ID,
+ /// The predeclared 'type_info' struct.
+ PREDEF_DECL_BUILTIN_MS_TYPE_INFO_TAG_ID,
+
#define BuiltinTemplate(BTName) PREDEF_DECL##BTName##_ID,
#include "clang/Basic/BuiltinTemplates.inc"
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index d50eeff0e4b3b..a1f707e601db3 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -443,9 +443,7 @@ void Sema::Initialize() {
if (getLangOpts().MSVCCompat) {
if (getLangOpts().CPlusPlus &&
IdResolver.begin(&Context.Idents.get("type_info")) == IdResolver.end())
- PushOnScopeChains(
- Context.buildImplicitRecord("type_info", TagTypeKind::Class),
- TUScope);
+ PushOnScopeChains(Context.getMSTypeInfoTagDecl(), TUScope);
addImplicitTypedef("size_t", Context.getSizeType());
}
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index f896f9f11c2b3..44b48b9b4711a 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -8318,6 +8318,9 @@ Decl *ASTReader::getPredefinedDecl(PredefinedDeclIDs ID) {
NewLoaded = Context.getCFConstantStringTagDecl();
break;
+ case PREDEF_DECL_BUILTIN_MS_TYPE_INFO_TAG_ID:
+ return Context.getMSTypeInfoTagDecl();
+
#define BuiltinTemplate(BTName) \
case PREDEF_DECL##BTName##_ID: \
if (Context.Decl##BTName) \
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index a6957e54b66f1..2b40be3b7349d 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -5618,6 +5618,8 @@ void ASTWriter::PrepareWritingSpecialDecls(Sema &SemaRef) {
PREDEF_DECL_BUILTIN_MS_VA_LIST_ID);
RegisterPredefDecl(Context.MSGuidTagDecl,
PREDEF_DECL_BUILTIN_MS_GUID_ID);
+ RegisterPredefDecl(Context.MSTypeInfoTagDecl,
+ PREDEF_DECL_BUILTIN_MS_TYPE_INFO_TAG_ID);
RegisterPredefDecl(Context.ExternCContext, PREDEF_DECL_EXTERN_C_CONTEXT_ID);
RegisterPredefDecl(Context.CFConstantStringTypeDecl,
PREDEF_DECL_CF_CONSTANT_STRING_ID);
diff --git a/clang/test/Modules/pr151277.cpp b/clang/test/Modules/pr151277.cpp
new file mode 100644
index 0000000000000..2428e854d6edf
--- /dev/null
+++ b/clang/test/Modules/pr151277.cpp
@@ -0,0 +1,15 @@
+// RUN: split-file %s %t
+
+// RUN: %clang_cc1 -I%t -emit-module -o %t/a.pcm -fmodules %t/module.modulemap -fno-implicit-modules -fmodule-name=a -x c++-header -fms-compatibility
+// RUN: %clang_cc1 -I%t -emit-module -o %t/b.pcm -fmodules %t/module.modulemap -fno-implicit-modules -fmodule-name=b -x c++-header -fms-compatibility -fmodule-file=%t/a.pcm
+
+//--- module.modulemap
+module a { header "a.h" }
+module b { header "b.h" }
+
+//--- a.h
+type_info* foo;
+
+//--- b.h
+type_info* bar;
+
|
This solves the "reference to `type_info` is ambiguous" error you get when attempting to reference `type_info` while depending on a module with `-fms-compatibility` enabled. Fixes llvm#38400
matts1
force-pushed
the
push-sruqkvlnlwpk
branch
from
47d44b2 to
ec1e606
Compare
shafik
requested review from
AaronBallman,
erichkeane and
ChuanqiXu9
and removed request for
AaronBallman
erichkeane
reviewed
Jul 30, 2025
shafik
reviewed
Jul 30, 2025
|
What's required to get this merged? It's blocking some of my work so I'd prefer it merged sooner rather than later. |
Sorry, wasn't clear you didn't have commit rights already. I'll merge this for you. |
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/10/builds/10818 Here is the relevant piece of the build log for the reference |
|
I've noticed that this PR changed the tag type kind of the implicit Seems like it is a |
erichkeane
added a commit
that referenced
this pull request
Aug 5, 2025
It was brought up on #151277 that the patch changes type_info from class to struct. While I couldn't find a way to test/notice this, this patch changes it to a class. While I'm here, I am also removing unnecessary/against coding standard curley brackets.
Oh, interesting! class vs struct can mangle differently in certain ABIs (and IIRC, Windows is one that it does!). That said, we mangle type_info special, so there is no real way I could find to notice the difference between class-vs-struct here. Either way, fixed here: 16766b3 |
|
Thanks! |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This fixes an ambiguous type type_info when you try and reference the
type_infotype while using clang modulemaps with-fms-compatibilityenabledFixes #38400