[clang] 4c2e49d - [C++20] [Modules] Don't profiling the callee of CXXFoldExpr (#190732)

[via cfe-commits]

Author: Chuanqi Xu
Date: 2026-04-07T07:04:49Z
New Revision: 4c2e49dc5ce3125be9fb07dcefe9be970ce739ec

URL: https://github.com/llvm/llvm-project/commit/4c2e49dc5ce3125be9fb07dcefe9be970ce739ec
DIFF: https://github.com/llvm/llvm-project/commit/4c2e49dc5ce3125be9fb07dcefe9be970ce739ec.diff

LOG: [C++20] [Modules] Don't profiling the callee of CXXFoldExpr (#190732)

Close https://github.com/llvm/llvm-project/issues/190333

For the test case, the root cause of the problem is, the compiler
thought the declaration of `operator &&` in consumer.cpp may change the
meaning of '&&' in the requrie clause of `F::operator()`. But it doesn't
make sense. Here we skip profiling the callee to solve the problem. Note
that we've already record the kind of the operator. So '&&' and '||'
won't be confused.

Added: 
    clang/test/Modules/callable-require-clause-merge.cppm

Modified: 
    clang/lib/AST/StmtProfile.cpp
    clang/test/Modules/polluted-operator.cppm

Removed: 
    


################################################################################
diff  --git a/clang/lib/AST/StmtProfile.cpp b/clang/lib/AST/StmtProfile.cpp
index e8c1f8a8ecb5f..af27a928edff6 100644
--- a/clang/lib/AST/StmtProfile.cpp
+++ b/clang/lib/AST/StmtProfile.cpp
@@ -2390,7 +2390,35 @@ void StmtProfiler::VisitMaterializeTemporaryExpr(
 }
 
 void StmtProfiler::VisitCXXFoldExpr(const CXXFoldExpr *S) {
-  VisitExpr(S);
+  // For CXXFoldExpr, not profile the call expression as it may
+  // be affected by the context. e.g.,
+  //
+  // "a.h"
+  //
+  //   struct F {
+  //     template <typename... T> requires ((sizeof(T) > 0) && ...)
+  //     void operator()(T...) {}
+  //   } f;
+  //
+  // and
+  //
+  // "c.h"
+  //
+  //   void operator&&(struct X, struct X);
+  //   #include "a.h"
+  //
+  // Here we may give 
diff erent profile results to F::operator() in
+  // "c.h" vs other use cases of "a.h". This is problematic in
+  // cases where we may have expression coming from 
diff erent
+  // headers, e.g., modules.
+  if (S->getLHS())
+    Visit(S->getLHS());
+  else
+    ID.AddInteger(0);
+  if (S->getRHS())
+    Visit(S->getRHS());
+  else
+    ID.AddInteger(0);
   ID.AddInteger(S->getOperator());
 }
 

diff  --git a/clang/test/Modules/callable-require-clause-merge.cppm b/clang/test/Modules/callable-require-clause-merge.cppm
new file mode 100644
index 0000000000000..ae49dd7a58542
--- /dev/null
+++ b/clang/test/Modules/callable-require-clause-merge.cppm
@@ -0,0 +1,35 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -std=c++20 %t/mymod.cppm -emit-module-interface -o %t/mymod.pcm
+// RUN: %clang_cc1 -std=c++20 %t/consumer.cpp -fprebuilt-module-path=%t -fsyntax-only -verify
+//
+// RUN: %clang_cc1 -std=c++20 %t/mymod.cppm -emit-reduced-module-interface -o %t/mymod.pcm
+// RUN: %clang_cc1 -std=c++20 %t/consumer.cpp -fprebuilt-module-path=%t -fsyntax-only -verify
+
+// RUN: %clang_cc1 -std=c++20 -fskip-odr-check-in-gmf %t/mymod.cppm -emit-module-interface -o %t/mymod.pcm
+// RUN: %clang_cc1 -std=c++20 -fskip-odr-check-in-gmf %t/consumer.cpp -fprebuilt-module-path=%t -fsyntax-only -verify
+//
+// RUN: %clang_cc1 -std=c++20 -fskip-odr-check-in-gmf %t/mymod.cppm -emit-reduced-module-interface -o %t/mymod.pcm
+// RUN: %clang_cc1 -std=c++20 -fskip-odr-check-in-gmf %t/consumer.cpp -fprebuilt-module-path=%t -fsyntax-only -verify
+
+//--- r.h
+struct F {
+  template <typename... T> requires ((sizeof(T) > 0) && ...)
+  void operator()(T...) {}
+} f;
+
+//--- mymod.cppm
+module;
+#include "r.h"
+export module mymod;
+export using ::f;
+
+//--- consumer.cpp
+// expected-no-diagnostics
+void operator&&(struct X, struct X);
+#include "r.h"
+import mymod;
+
+void g() { f(); }

diff  --git a/clang/test/Modules/polluted-operator.cppm b/clang/test/Modules/polluted-operator.cppm
index 45cc5e37d6a64..e81a63c3e03de 100644
--- a/clang/test/Modules/polluted-operator.cppm
+++ b/clang/test/Modules/polluted-operator.cppm
@@ -49,8 +49,6 @@ namespace std
 
 //--- a.cppm
 module;
-// The operator&& defined in 'foo.h' will pollute the 
-// expression '__is_trivial(_Types) && ...' in bar.h
 #include "foo.h"
 #include "bar.h"
 export module a;
@@ -71,9 +69,4 @@ export namespace std {
   using std::operator&&;
 }
 
-#ifdef SKIP_ODR_CHECK_IN_GMF
 // expected-no-diagnostics
-#else
-// expected-error@* {{has 
diff erent definitions in 
diff erent modules; first 
diff erence is defined here found data member '_S_copy_ctor' with an initializer}}
-// expected-note@* {{but in 'a.<global>' found data member '_S_copy_ctor' with a 
diff erent initializer}}
-#endif