[clang] Avoid assert in substqualifier (PR #182707)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Ayush Kumar Gaur (Ayush3941)

<details>
<summary>Changes</summary>

Replace an assertion in SubstQualifier with a guarded early return when
encountering non-friend qualified declarations inside dependent contexts.

Invalid code during template instantiation may reach this path during
error recovery  causing an ICE  Instead of asserting treat this as a
substitution failure and abort qualifier substitution gracefully

Fixes #<!-- -->176152.

---
Full diff: https://github.com/llvm/llvm-project/pull/182707.diff


2 Files Affected:

- (modified) clang/lib/Sema/SemaTemplateInstantiateDecl.cpp (+4-3) 
- (added) clang/test/SemaTemplate/GH176152.cpp (+12) 


``````````diff
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index e74c41517ecbf..77c4d732febac 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -55,9 +55,10 @@ static bool SubstQualifier(Sema &SemaRef, const DeclT *OldDecl, DeclT *NewDecl,
   if (!OldDecl->getQualifierLoc())
     return false;
 
-  assert((NewDecl->getFriendObjectKind() ||
-          !OldDecl->getLexicalDeclContext()->isDependentContext()) &&
-         "non-friend with qualified name defined in dependent context");
+  if (!NewDecl->getFriendObjectKind() &&
+      OldDecl->getLexicalDeclContext()->isDependentContext()) {
+    return true;
+  }
   Sema::ContextRAII SavedContext(
       SemaRef,
       const_cast<DeclContext *>(NewDecl->getFriendObjectKind()
diff --git a/clang/test/SemaTemplate/GH176152.cpp b/clang/test/SemaTemplate/GH176152.cpp
new file mode 100644
index 0000000000000..7d61aa292982d
--- /dev/null
+++ b/clang/test/SemaTemplate/GH176152.cpp
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -std=c++23 -fsyntax-only -verify %s
+
+template <class T> int f(T) {
+  struct MyClass {
+    static int staticField;
+    // expected-error at -1 {{static data member 'staticField' not allowed in local struct 'MyClass'}}
+  };
+  int MyClass::staticField = 42;
+  return 0;
+}
+
+int x = f(0);

``````````

</details>


https://github.com/llvm/llvm-project/pull/182707