[PATCH] D151200: [Clang][C++20] Error out if parameter types of a defaulted comparion operator are not all the same.

[Jens Massberg via Phabricator via cfe-commits]

massberg updated this revision to Diff 524704.
massberg added a comment.

Also error out if the comparion operator has a single parameter that isn't a 
const reference. See also 
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p2002r1.html on how it 
shpuld behave in C++20.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D151200/new/

https://reviews.llvm.org/D151200

Files:
  clang/lib/Sema/SemaDeclCXX.cpp
  clang/test/CXX/class/class.compare/class.compare.default/p1.cpp


Index: clang/test/CXX/class/class.compare/class.compare.default/p1.cpp
===================================================================
--- clang/test/CXX/class/class.compare/class.compare.default/p1.cpp
+++ clang/test/CXX/class/class.compare/class.compare.default/p1.cpp
@@ -27,6 +27,16 @@
     bool operator==(const A&) const = default; // expected-error {{comparison 
operator template cannot be defaulted}}
 };
 
+template<class C> struct D {
+  C i;
+  friend bool operator==(const D&, D) = default; // expected-error {{must have 
the same type}}
+  friend bool operator>(D, const D&) = default; // expected-error {{must have 
the same type}}
+  friend bool operator<(const D&, const D&) = default;
+  friend bool operator<=(D, D) = default;
+
+  bool operator!=(D) const = default; // expected-error {{invalid parameter 
type for defaulted equality comparison operator}}
+};
+
 template<typename T> struct Dependent {
   using U = typename T::type;
   bool operator==(U) const = default; // expected-error {{found 'U'}}
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -8626,8 +8626,7 @@
   const ParmVarDecl *KnownParm = nullptr;
   for (const ParmVarDecl *Param : FD->parameters()) {
     QualType ParmTy = Param->getType();
-    if (ParmTy->isDependentType())
-      continue;
+
     if (!KnownParm) {
       auto CTy = ParmTy;
       // Is it `T const &`?



Index: clang/test/CXX/class/class.compare/class.compare.default/p1.cpp
===================================================================
--- clang/test/CXX/class/class.compare/class.compare.default/p1.cpp
+++ clang/test/CXX/class/class.compare/class.compare.default/p1.cpp
@@ -27,6 +27,16 @@
     bool operator==(const A&) const = default; // expected-error {{comparison operator template cannot be defaulted}}
 };
 
+template<class C> struct D {
+  C i;
+  friend bool operator==(const D&, D) = default; // expected-error {{must have the same type}}
+  friend bool operator>(D, const D&) = default; // expected-error {{must have the same type}}
+  friend bool operator<(const D&, const D&) = default;
+  friend bool operator<=(D, D) = default;
+
+  bool operator!=(D) const = default; // expected-error {{invalid parameter type for defaulted equality comparison operator}}
+};
+
 template<typename T> struct Dependent {
   using U = typename T::type;
   bool operator==(U) const = default; // expected-error {{found 'U'}}
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -8626,8 +8626,7 @@
   const ParmVarDecl *KnownParm = nullptr;
   for (const ParmVarDecl *Param : FD->parameters()) {
     QualType ParmTy = Param->getType();
-    if (ParmTy->isDependentType())
-      continue;
+
     if (!KnownParm) {
       auto CTy = ParmTy;
       // Is it `T const &`?

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