[clang] [NFC] Fix formatting for #80963 (PR #131100)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Kuo, Mei-Chun (Megan0704-1)

<details>
<summary>Changes</summary>

This PR fixes formatting issues in `constructor-template.cpp` introduced in #<!-- -->130866.  

Changes:  
- Ran `clang-format` to adhere to LLVM style guidelines.  
- No functional changes.  

CC: @<!-- -->cor3ntin @<!-- -->shafik 
Thanks

---
Full diff: https://github.com/llvm/llvm-project/pull/131100.diff


4 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+1) 
- (modified) clang/lib/Sema/SemaDeclCXX.cpp (+1-2) 
- (added) clang/test/SemaCXX/copy-ctor-template.cpp (+29) 
- (modified) clang/test/SemaTemplate/constructor-template.cpp (+8-7) 


``````````diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 004f78f22ac36..8bae0d6e99ae0 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -293,6 +293,7 @@ Bug Fixes to Attribute Support
 Bug Fixes to C++ Support
 ^^^^^^^^^^^^^^^^^^^^^^^^
 
+- Clang now diagnoses copy constructors taking the class by value in template instantiations. (#GH130866)
 - Clang is now better at keeping track of friend function template instance contexts. (#GH55509)
 - Clang now prints the correct instantiation context for diagnostics suppressed
   by template argument deduction.
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 96aac7871db1e..00b4006b5eb43 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -10921,8 +10921,7 @@ void Sema::CheckConstructor(CXXConstructorDecl *Constructor) {
   //   parameters have default arguments.
   if (!Constructor->isInvalidDecl() &&
       Constructor->hasOneParamOrDefaultArgs() &&
-      Constructor->getTemplateSpecializationKind() !=
-          TSK_ImplicitInstantiation) {
+      !Constructor->isFunctionTemplateSpecialization()) {
     QualType ParamType = Constructor->getParamDecl(0)->getType();
     QualType ClassTy = Context.getTagDeclType(ClassDecl);
     if (Context.getCanonicalType(ParamType).getUnqualifiedType() == ClassTy) {
diff --git a/clang/test/SemaCXX/copy-ctor-template.cpp b/clang/test/SemaCXX/copy-ctor-template.cpp
new file mode 100644
index 0000000000000..c58bd7c0c5e10
--- /dev/null
+++ b/clang/test/SemaCXX/copy-ctor-template.cpp
@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+template<class T, class V>
+struct A{
+    A(); // expected-note{{candidate constructor not viable: requires 0 arguments, but 1 was provided}}
+    A(A&); // expected-note{{candidate constructor not viable: expects an lvalue for 1st argument}} 
+    A(A<V, T>); // expected-error{{copy constructor must pass its first argument by reference}}
+};
+
+void f() {
+    A<int, int> a = A<int, int>(); // expected-note{{in instantiation of template class 'A<int, int>'}} 
+    A<int, double> a1 = A<double, int>(); // No error (not a copy constructor)
+}
+
+// Test rvalue-to-lvalue conversion in copy constructor
+A<int, int> &&a(void);
+void g() {
+    A<int, int> a2 = a(); // expected-error{{no matching constructor}}
+}
+
+template<class T, class V>
+struct B{
+    B();
+    template<class U> B(U); // No error (templated constructor)
+};
+
+void h() {
+    B<int, int> b = B<int, int>(); // should use implicit copy constructor
+}
diff --git a/clang/test/SemaTemplate/constructor-template.cpp b/clang/test/SemaTemplate/constructor-template.cpp
index a89dc60cfa347..13f00beb1ffc5 100644
--- a/clang/test/SemaTemplate/constructor-template.cpp
+++ b/clang/test/SemaTemplate/constructor-template.cpp
@@ -73,7 +73,7 @@ struct X3 {
   template<typename T> X3(T);
 };
 
-template<> X3::X3(X3); // expected-error{{must pass its first argument by reference}}
+template<> X3::X3(X3); // No error (template constructor)
 
 struct X4 {
   X4();
@@ -139,12 +139,12 @@ namespace self_by_value {
   template <class T, class U> struct A {
     A() {}
     A(const A<T,U> &o) {}
-    A(A<T,T> o) {}
+    A(A<T,T> o) {} // expected-error{{copy constructor must pass its first argument by reference}}
   };
 
   void helper(A<int,float>);
 
-  void test1(A<int,int> a) {
+  void test1(A<int,int> a) { // expected-note{{in instantiation of template class 'self_by_value::A<int, int>'}}
     helper(a);
   }
   void test2() {
@@ -156,12 +156,13 @@ namespace self_by_value_2 {
   template <class T, class U> struct A {
     A() {} // precxx17-note {{not viable: requires 0 arguments}}
     A(A<T,U> &o) {} // precxx17-note {{not viable: expects an lvalue}}
-    A(A<T,T> o) {} // precxx17-note {{ignored: instantiation takes its own class type by value}}
+    A(A<T,T> o) {} // expected-error{{copy constructor must pass its first argument by reference}}
   };
 
   void helper_A(A<int,int>); // precxx17-note {{passing argument to parameter here}}
   void test_A() {
-    helper_A(A<int,int>()); // precxx17-error {{no matching constructor}}
+    helper_A(A<int,int>()); // precxx17-error {{no matching constructor}} \
+                            // expected-note{{in instantiation of template class 'self_by_value_2::A<int, int>'}}
   }
 }
 
@@ -169,11 +170,11 @@ namespace self_by_value_3 {
   template <class T, class U> struct A {
     A() {}
     A(A<T,U> &o) {}
-    A(A<T,T> o) {}
+    A(A<T,T> o) {} // expected-error{{copy constructor must pass its first argument by reference}}
   };
 
   void helper_A(A<int,int>);
-  void test_A(A<int,int> b) {
+  void test_A(A<int,int> b) { // expected-note{{in instantiation of template class 'self_by_value_3::A<int, int>'}}
     helper_A(b);
   }
 }

``````````

</details>


https://github.com/llvm/llvm-project/pull/131100