[libc++] Declare <compare> operators with the proper visibility attribute

[ldionne]

Summary

Many operators in <compare> were _defined_ with the proper visibility attribute,
but they were _declared_ without any. This is not a problem until we change the
definition of _LIBCPP_INLINE_VISIBILITY to something that requires the
declaration to be decorated.

I also marked strong_equality::operator weak_equality() as
_LIBCPP_INLINE_VISIBILITY, since it seems like it had been forgotten.

This came up while trying to get rid of __attribute__((__always_inline__))
in favor of __attribute__((internal_linkage)).

[EricWF]

I have a series of libc++ clang-tidy checks in a clang-tool-extra fork. One of them being visibility-attr-not-on-first-decl, perhaps I should try to upstream it.

[ldionne]

In D49104#1156639, @EricWF wrote:

I have a series of libc++ clang-tidy checks in a clang-tool-extra fork. One of them being visibility-attr-not-on-first-decl, perhaps I should try to upstream it.

That would be great!

libcxx/trunk/include/compare

 class  weak_equality {
   _LIBCPP_INLINE_VISIBILITY
   constexpr explicit weak_equality(_EqResult __val) noexcept : __value_(__val) {}
 
 public:
   static const weak_equality equivalent;
   static const weak_equality nonequivalent;
 
-  friend constexpr bool operator==(weak_equality __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator==(_CmpUnspecifiedParam, weak_equality __v) noexcept;
-  friend constexpr bool operator!=(weak_equality __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator!=(_CmpUnspecifiedParam, weak_equality __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(weak_equality __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(_CmpUnspecifiedParam, weak_equality __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator!=(weak_equality __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator!=(_CmpUnspecifiedParam, weak_equality __v) noexcept;
 
 #ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
-  friend constexpr weak_equality operator<=>(weak_equality __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr weak_equality operator<=>(_CmpUnspecifiedParam, weak_equality __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr weak_equality operator<=>(weak_equality __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr weak_equality operator<=>(_CmpUnspecifiedParam, weak_equality __v) noexcept;
 #endif
 
 private:
   _EqResult __value_;
 };
 
 _LIBCPP_INLINE_VAR constexpr weak_equality weak_equality::equivalent(_EqResult::__equiv);
 _LIBCPP_INLINE_VAR constexpr weak_equality weak_equality::nonequivalent(_EqResult::__nonequiv);

 
 public:
   static const strong_equality equal;
   static const strong_equality nonequal;
   static const strong_equality equivalent;
   static const strong_equality nonequivalent;
 
   // conversion
-  constexpr operator weak_equality() const noexcept {
+  _LIBCPP_INLINE_VISIBILITY constexpr operator weak_equality() const noexcept {
     return __value_ == _EqResult::__zero ? weak_equality::equivalent
           : weak_equality::nonequivalent;
   }
 
   // comparisons
-  friend constexpr bool operator==(strong_equality __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator!=(strong_equality __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator==(_CmpUnspecifiedParam, strong_equality __v) noexcept;
-  friend constexpr bool operator!=(_CmpUnspecifiedParam, strong_equality __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(strong_equality __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator!=(strong_equality __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(_CmpUnspecifiedParam, strong_equality __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator!=(_CmpUnspecifiedParam, strong_equality __v) noexcept;
 
 #ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
-  friend constexpr strong_equality operator<=>(strong_equality __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr strong_equality operator<=>(_CmpUnspecifiedParam, strong_equality __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr strong_equality operator<=>(strong_equality __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr strong_equality operator<=>(_CmpUnspecifiedParam, strong_equality __v) noexcept;
 #endif
 private:
   _EqResult __value_;
 };
 
 _LIBCPP_INLINE_VAR constexpr strong_equality strong_equality::equal(_EqResult::__equal);
 _LIBCPP_INLINE_VAR constexpr strong_equality strong_equality::nonequal(_EqResult::__nonequal);
 _LIBCPP_INLINE_VAR constexpr strong_equality strong_equality::equivalent(_EqResult::__equiv);
public:
   static const partial_ordering unordered;
 
   // conversion
   constexpr operator weak_equality() const noexcept {
     return __value_ == 0 ? weak_equality::equivalent : weak_equality::nonequivalent;
   }
 
   // comparisons
-  friend constexpr bool operator==(partial_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator!=(partial_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator< (partial_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator<=(partial_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator> (partial_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator>=(partial_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator==(_CmpUnspecifiedParam, partial_ordering __v) noexcept;
-  friend constexpr bool operator!=(_CmpUnspecifiedParam, partial_ordering __v) noexcept;
-  friend constexpr bool operator< (_CmpUnspecifiedParam, partial_ordering __v) noexcept;
-  friend constexpr bool operator<=(_CmpUnspecifiedParam, partial_ordering __v) noexcept;
-  friend constexpr bool operator> (_CmpUnspecifiedParam, partial_ordering __v) noexcept;
-  friend constexpr bool operator>=(_CmpUnspecifiedParam, partial_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(partial_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator!=(partial_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator< (partial_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(partial_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator> (partial_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(partial_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(_CmpUnspecifiedParam, partial_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator!=(_CmpUnspecifiedParam, partial_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator< (_CmpUnspecifiedParam, partial_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(_CmpUnspecifiedParam, partial_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator> (_CmpUnspecifiedParam, partial_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(_CmpUnspecifiedParam, partial_ordering __v) noexcept;
 
 #ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
-  friend constexpr partial_ordering operator<=>(partial_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr partial_ordering operator<=>(_CmpUnspecifiedParam, partial_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr partial_ordering operator<=>(partial_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr partial_ordering operator<=>(_CmpUnspecifiedParam, partial_ordering __v) noexcept;
 #endif
 
 private:
   _ValueT __value_;
 };
 
 _LIBCPP_INLINE_VAR constexpr partial_ordering partial_ordering::less(_OrdResult::__less);
 _LIBCPP_INLINE_VAR constexpr partial_ordering partial_ordering::equivalent(_EqResult::__equiv);
public:
 
   _LIBCPP_INLINE_VISIBILITY
   constexpr operator partial_ordering() const noexcept {
     return __value_ == 0 ? partial_ordering::equivalent
         : (__value_ < 0 ? partial_ordering::less : partial_ordering::greater);
   }
 
   // comparisons
-  friend constexpr bool operator==(weak_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator!=(weak_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator< (weak_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator<=(weak_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator> (weak_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator>=(weak_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator==(_CmpUnspecifiedParam, weak_ordering __v) noexcept;
-  friend constexpr bool operator!=(_CmpUnspecifiedParam, weak_ordering __v) noexcept;
-  friend constexpr bool operator< (_CmpUnspecifiedParam, weak_ordering __v) noexcept;
-  friend constexpr bool operator<=(_CmpUnspecifiedParam, weak_ordering __v) noexcept;
-  friend constexpr bool operator> (_CmpUnspecifiedParam, weak_ordering __v) noexcept;
-  friend constexpr bool operator>=(_CmpUnspecifiedParam, weak_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(weak_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator!=(weak_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator< (weak_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(weak_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator> (weak_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(weak_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(_CmpUnspecifiedParam, weak_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator!=(_CmpUnspecifiedParam, weak_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator< (_CmpUnspecifiedParam, weak_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(_CmpUnspecifiedParam, weak_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator> (_CmpUnspecifiedParam, weak_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(_CmpUnspecifiedParam, weak_ordering __v) noexcept;
 
 #ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
-  friend constexpr weak_ordering operator<=>(weak_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr weak_ordering operator<=>(_CmpUnspecifiedParam, weak_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr weak_ordering operator<=>(weak_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr weak_ordering operator<=>(_CmpUnspecifiedParam, weak_ordering __v) noexcept;
 #endif
 
 private:
   _ValueT __value_;
 };
 
 _LIBCPP_INLINE_VAR constexpr weak_ordering weak_ordering::less(_OrdResult::__less);
 _LIBCPP_INLINE_VAR constexpr weak_ordering weak_ordering::equivalent(_EqResult::__equiv);
public:
 
   _LIBCPP_INLINE_VISIBILITY
   constexpr operator weak_ordering() const noexcept {
     return __value_ == 0 ? weak_ordering::equivalent
         : (__value_ < 0 ? weak_ordering::less : weak_ordering::greater);
   }
 
   // comparisons
-  friend constexpr bool operator==(strong_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator!=(strong_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator< (strong_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator<=(strong_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator> (strong_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator>=(strong_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr bool operator==(_CmpUnspecifiedParam, strong_ordering __v) noexcept;
-  friend constexpr bool operator!=(_CmpUnspecifiedParam, strong_ordering __v) noexcept;
-  friend constexpr bool operator< (_CmpUnspecifiedParam, strong_ordering __v) noexcept;
-  friend constexpr bool operator<=(_CmpUnspecifiedParam, strong_ordering __v) noexcept;
-  friend constexpr bool operator> (_CmpUnspecifiedParam, strong_ordering __v) noexcept;
-  friend constexpr bool operator>=(_CmpUnspecifiedParam, strong_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(strong_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator!=(strong_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator< (strong_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(strong_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator> (strong_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(strong_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator==(_CmpUnspecifiedParam, strong_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator!=(_CmpUnspecifiedParam, strong_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator< (_CmpUnspecifiedParam, strong_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator<=(_CmpUnspecifiedParam, strong_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator> (_CmpUnspecifiedParam, strong_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr bool operator>=(_CmpUnspecifiedParam, strong_ordering __v) noexcept;
 
 #ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
-  friend constexpr strong_ordering operator<=>(strong_ordering __v, _CmpUnspecifiedParam) noexcept;
-  friend constexpr strong_ordering operator<=>(_CmpUnspecifiedParam, strong_ordering __v) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr strong_ordering operator<=>(strong_ordering __v, _CmpUnspecifiedParam) noexcept;
+  _LIBCPP_INLINE_VISIBILITY friend constexpr strong_ordering operator<=>(_CmpUnspecifiedParam, strong_ordering __v) noexcept;
 #endif
 
 private:
   _ValueT __value_;
 };
 
 _LIBCPP_INLINE_VAR constexpr strong_ordering strong_ordering::less(_OrdResult::__less);
 _LIBCPP_INLINE_VAR constexpr strong_ordering strong_ordering::equal(_EqResult::__equal);