[clang] [clang] Clang should detect illegal copy constructor with template class as its parameter (PR #81251)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Rajveer Singh Bharadwaj (Rajveer100)

<details>
<summary>Changes</summary>

Resolves Issue #<!-- -->80963

As described in the snippet of the issue, `A<T,V>` is correctly detected while it fails to reject in other cases.

---
Full diff: https://github.com/llvm/llvm-project/pull/81251.diff


2 Files Affected:

- (modified) clang/lib/Sema/SemaDeclCXX.cpp (+1-1) 
- (added) clang/test/SemaCXX/GH80963.cpp (+15) 


``````````diff
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index ab8a967b06a456..9778679ee40d47 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -10918,7 +10918,7 @@ void Sema::CheckConstructor(CXXConstructorDecl *Constructor) {
   //   parameters have default arguments.
   if (!Constructor->isInvalidDecl() &&
       Constructor->hasOneParamOrDefaultArgs() &&
-      Constructor->getTemplateSpecializationKind() !=
+      Constructor->getTemplateSpecializationKind() ==
           TSK_ImplicitInstantiation) {
     QualType ParamType = Constructor->getParamDecl(0)->getType();
     QualType ClassTy = Context.getTagDeclType(ClassDecl);
diff --git a/clang/test/SemaCXX/GH80963.cpp b/clang/test/SemaCXX/GH80963.cpp
new file mode 100644
index 00000000000000..55779e6ff191b7
--- /dev/null
+++ b/clang/test/SemaCXX/GH80963.cpp
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+template < class T, class V > struct A
+{
+    A ();
+    A (A &);
+    A (A < V,T >);
+    // expected-error at -1 {{copy constructor must pass its first argument by reference}}
+};
+
+void f ()
+{
+    A <int, int> (A < int, int >());
+    // expected-note at -1 {{in instantiation of template class 'A<int, int>' requested here}}
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/81251