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

[Rajveer Singh Bharadwaj via cfe-commits]

https://github.com/Rajveer100 created https://github.com/llvm/llvm-project/pull/81251

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.

>From c931dd64e63817619c6b7f649828580b3fb2e6ec Mon Sep 17 00:00:00 2001
From: Rajveer <rajveer.developer at icloud.com>
Date: Fri, 9 Feb 2024 19:20:39 +0530
Subject: [PATCH] [clang] Clang should detect illegal copy constructor with
 template class as its parameter

Resolves Issue #80963
---
 clang/lib/Sema/SemaDeclCXX.cpp |  2 +-
 clang/test/SemaCXX/GH80963.cpp | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 clang/test/SemaCXX/GH80963.cpp

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}}
+}