commit 98feb05825a179c56f965d936b948a95d2a6b888
author Matheus Izvekov <mizvekov@gmail.com> Wed Apr 09 23:23:52 2025 -0300
committer GitHub <noreply@github.com> Wed Apr 09 23:23:52 2025 -0300
tree 4386a56f4214b0a038a8db98988b33fc5d5c4a1e
parent 02fde3a6518b1085946b891e2a1b3550f7497888

[clang] fix unresolved dependent template specialization mangling (#135111)

This fixes a regression introduced in
https://github.com/llvm/llvm-project/pull/133610 which was reported here
https://github.com/llvm/llvm-project/pull/133610#issuecomment-2787332042

When mangling a dependent template specialization appearing within an
unresolved prefix, translate the dtst back to a dependent template name
including the prefix, and mangle following the nested unresolved-type
production.

There are no release notes, since this regression was never released.

clang/lib/AST/ItaniumMangle.cpp

diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
index eb25b19..8790a52 100644
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -1404,9 +1404,19 @@
     //   - a template type parameter
     //   - a template template parameter with arguments
     // In all of these cases, we should have no prefix.
-    if (qualifier->getPrefix()) {
-      mangleUnresolvedPrefix(qualifier->getPrefix(),
-                             /*recursive*/ true);
+    if (NestedNameSpecifier *Prefix = qualifier->getPrefix()) {
+      if (const auto *DTST =
+              dyn_cast<DependentTemplateSpecializationType>(type)) {
+        Out << "srN";
+        TemplateName Template = getASTContext().getDependentTemplateName(
+            {Prefix, DTST->getDependentTemplateName().getName(),
+             /*HasTemplateKeyword=*/true});
+        mangleTemplatePrefix(Template);
+        mangleTemplateArgs(Template, DTST->template_arguments());
+        break;
+      }
+      mangleUnresolvedPrefix(Prefix,
+                             /*recursive=*/true);
     } else {
       // Otherwise, all the cases want this.
       Out << "sr";

clang/test/CodeGenCXX/mangle-template.cpp

diff --git a/clang/test/CodeGenCXX/mangle-template.cpp b/clang/test/CodeGenCXX/mangle-template.cpp
index a4cb227..365aba5 100644
--- a/clang/test/CodeGenCXX/mangle-template.cpp
+++ b/clang/test/CodeGenCXX/mangle-template.cpp
@@ -70,7 +70,7 @@
     static const unsigned value = sizeof(T);
   };
 
-  template<unsigned> struct int_c { 
+  template<unsigned> struct int_c {
     typedef float type;
   };
 
@@ -92,7 +92,7 @@
     };
   };
 
-  template<unsigned> struct int_c { 
+  template<unsigned> struct int_c {
     typedef float type;
   };
 
@@ -399,3 +399,20 @@
   // CHECK: @_ZN14type_qualifier1gIPiEEvDTcmcvv_ELi1EE
   template void g<int*>(int);
 }
+
+namespace unresolved_template_specialization_type {
+  template <int> struct enable_if {};
+  struct Foo {
+    static const int value = true;
+  };
+  struct HashStateBase {
+    template <typename> using is_hashable = Foo;
+  };
+  template <class> struct raw_hash_set {
+    template <typename H>
+    static enable_if<H::template is_hashable<int>::value>
+        AbslHashValue() {}
+  };
+  template enable_if<true> raw_hash_set<int>::AbslHashValue<HashStateBase>();
+  // CHECH: @_ZN39unresolved_template_specialization_type12raw_hash_setIiE13AbslHashValueINS_13HashStateBaseEEENS_9enable_ifIXsrNT_11is_hashableIiEE5valueEEEv
+} // namespace unresolved_template_specialization_type