[clang] makes built-in traits match their stdlib counterparts' names

[cjdb]

Summary

The original names apparently broke convention by not making them the
same as the C++ type trait names, so we're creating aliases for them.
It's unclear whether or not the existing names can be deprecated and
removed in the future.

[cjdb]

Looks like I need to special-case __is_null_pointer as a function for libstdc++.

[aaron.ballman]

In D149492#4311026, @cjdb wrote:

Looks like I need to special-case __is_null_pointer as a function for libstdc++.

Yeah, precommit CI found an issue with that.

clang/include/clang/Basic/TokenKinds.def

 TYPE_TRAIT_1(__is_trivially_copyable, IsTriviallyCopyable, KEYCXX)
 TYPE_TRAIT_1(__is_union, IsUnion, KEYCXX)
 TYPE_TRAIT_1(__has_unique_object_representations,
              HasUniqueObjectRepresentations, KEYCXX)
 
 #define TRANSFORM_TYPE_TRAIT_DEF(_, Trait) KEYWORD(__##Trait, KEYCXX)
 #include "clang/Basic/TransformTypeTraits.def"
 
+ALIAS("__remove_reference", __remove_reference_t, KEYCXX)
+
 // Clang-only C++ Type Traits
 TYPE_TRAIT_1(__is_trivially_relocatable, IsTriviallyRelocatable, KEYCXX)
 TYPE_TRAIT_1(__is_trivially_equality_comparable, IsTriviallyEqualityComparable, KEYCXX)
 TYPE_TRAIT_1(__is_bounded_array, IsBoundedArray, KEYCXX)
 TYPE_TRAIT_1(__is_unbounded_array, IsUnboundedArray, KEYCXX)
 TYPE_TRAIT_1(__is_nullptr, IsNullPointer, KEYCXX)
+ALIAS("__is_null_pointer", __is_nullptr, KEYCXX)
 TYPE_TRAIT_1(__is_scoped_enum, IsScopedEnum, KEYCXX)
 TYPE_TRAIT_1(__is_referenceable, IsReferenceable, KEYCXX)
 TYPE_TRAIT_1(__can_pass_in_regs, CanPassInRegs, KEYCXX)
 TYPE_TRAIT_2(__reference_binds_to_temporary, ReferenceBindsToTemporary, KEYCXX)
 
 // Embarcadero Expression Traits
 EXPRESSION_TRAIT(__is_lvalue_expr, IsLValueExpr, KEYCXX)
 EXPRESSION_TRAIT(__is_rvalue_expr, IsRValueExpr, KEYCXX)

clang/test/SemaCXX/type-traits.cpp

void is_null_pointer() {
   static_assert(!__is_nullptr(Derives), "");
   static_assert(!__is_nullptr(Enum), "");
   static_assert(!__is_nullptr(IntArNB), "");
   static_assert(!__is_nullptr(Union), "");
   static_assert(!__is_nullptr(UnionAr), "");
   static_assert(!__is_nullptr(StructWithMembers), "");
   static_assert(!__is_nullptr(int StructWithMembers::*), "");
   static_assert(!__is_nullptr(void(StructWithMembers::*)()), "");
+
+  static_assert(__is_null_pointer(decltype(nullptr)), "");
+  static_assert(!__is_null_pointer(void *), "");
+  static_assert(!__is_null_pointer(cvoid *), "");
+  static_assert(!__is_null_pointer(cvoid *), "");
+  static_assert(!__is_null_pointer(char *), "");
+  static_assert(!__is_null_pointer(int *), "");
+  static_assert(!__is_null_pointer(int **), "");
+  static_assert(!__is_null_pointer(ClassType *), "");
+  static_assert(!__is_null_pointer(Derives *), "");
+  static_assert(!__is_null_pointer(Enum *), "");
+  static_assert(!__is_null_pointer(IntArNB *), "");
+  static_assert(!__is_null_pointer(Union *), "");
+  static_assert(!__is_null_pointer(UnionAr *), "");
+  static_assert(!__is_null_pointer(StructWithMembers *), "");
+  static_assert(!__is_null_pointer(void (*)()), "");
+
+  static_assert(!__is_null_pointer(void), "");
+  static_assert(!__is_null_pointer(cvoid), "");
+  static_assert(!__is_null_pointer(cvoid), "");
+  static_assert(!__is_null_pointer(char), "");
+  static_assert(!__is_null_pointer(int), "");
+  static_assert(!__is_null_pointer(int), "");
+  static_assert(!__is_null_pointer(ClassType), "");
+  static_assert(!__is_null_pointer(Derives), "");
+  static_assert(!__is_null_pointer(Enum), "");
+  static_assert(!__is_null_pointer(IntArNB), "");
+  static_assert(!__is_null_pointer(Union), "");
+  static_assert(!__is_null_pointer(UnionAr), "");
+  static_assert(!__is_null_pointer(StructWithMembers), "");
+  static_assert(!__is_null_pointer(int StructWithMembers::*), "");
+  static_assert(!__is_null_pointer(void(StructWithMembers::*)()), "");
 }
 
 void is_member_object_pointer()
 {
   StructWithMembers x;
 
   int t01[T(__is_member_object_pointer(int StructWithMembers::*))];
 
void add_rvalue_reference() {
   static_assert(__is_same(add_rvalue_reference_t<const S>, const S &&), "");
   static_assert(__is_same(add_rvalue_reference_t<volatile S>, volatile S &&), "");
   static_assert(__is_same(add_rvalue_reference_t<const volatile S>, const volatile S &&), "");
   static_assert(__is_same(add_rvalue_reference_t<int S::*>, int S::*&&), "");
   static_assert(__is_same(add_rvalue_reference_t<int (S::*)()>, int(S::* &&)()), "");
 }
 
 template <class T> using remove_reference_t = __remove_reference_t(T);
+template <class T> using remove_reference = __remove_reference(T);
 
 void check_remove_reference() {
   static_assert(__is_same(remove_reference_t<void>, void), "");
   static_assert(__is_same(remove_reference_t<const volatile void>, const volatile void), "");
   static_assert(__is_same(remove_reference_t<int>, int), "");
   static_assert(__is_same(remove_reference_t<const int>, const int), "");
   static_assert(__is_same(remove_reference_t<volatile int>, volatile int), "");
   static_assert(__is_same(remove_reference_t<const volatile int>, const volatile int), "");
void check_remove_reference() {
   static_assert(__is_same(remove_reference_t<volatile S &>, volatile S), "");
   static_assert(__is_same(remove_reference_t<volatile S &&>, volatile S), "");
   static_assert(__is_same(remove_reference_t<const volatile S>, const volatile S), "");
   static_assert(__is_same(remove_reference_t<const volatile S &>, const volatile S), "");
   static_assert(__is_same(remove_reference_t<const volatile S &&>, const volatile S), "");
   static_assert(__is_same(remove_reference_t<int S::*const volatile &>, int S::*const volatile), "");
   static_assert(__is_same(remove_reference_t<int (S::*const volatile &)()>, int(S::*const volatile)()), "");
   static_assert(__is_same(remove_reference_t<int (S::*const volatile &&)() &>, int(S::*const volatile)() &), "");
+
+  static_assert(__is_same(remove_reference<void>, void), "");
+  static_assert(__is_same(remove_reference<const volatile void>, const volatile void), "");
+  static_assert(__is_same(remove_reference<int>, int), "");
+  static_assert(__is_same(remove_reference<const int>, const int), "");
+  static_assert(__is_same(remove_reference<volatile int>, volatile int), "");
+  static_assert(__is_same(remove_reference<const volatile int>, const volatile int), "");
+  static_assert(__is_same(remove_reference<int *>, int *), "");
+  static_assert(__is_same(remove_reference<int *const volatile>, int *const volatile), "");
+  static_assert(__is_same(remove_reference<int const *const volatile>, int const *const volatile), "");
+  static_assert(__is_same(remove_reference<int &>, int), "");
+  static_assert(__is_same(remove_reference<int const volatile &>, int const volatile), "");
+  static_assert(__is_same(remove_reference<int &&>, int), "");
+  static_assert(__is_same(remove_reference<int const volatile &&>, int const volatile), "");
+  static_assert(__is_same(remove_reference<int()>, int()), "");
+  static_assert(__is_same(remove_reference<int (*const volatile)()>, int (*const volatile)()), "");
+  static_assert(__is_same(remove_reference<int (&)()>, int()), "");
+
+  static_assert(__is_same(remove_reference<S>, S), "");
+  static_assert(__is_same(remove_reference<S &>, S), "");
+  static_assert(__is_same(remove_reference<S &&>, S), "");
+  static_assert(__is_same(remove_reference<const S>, const S), "");
+  static_assert(__is_same(remove_reference<const S &>, const S), "");
+  static_assert(__is_same(remove_reference<const S &&>, const S), "");
+  static_assert(__is_same(remove_reference<volatile S>, volatile S), "");
+  static_assert(__is_same(remove_reference<volatile S &>, volatile S), "");
+  static_assert(__is_same(remove_reference<volatile S &&>, volatile S), "");
+  static_assert(__is_same(remove_reference<const volatile S>, const volatile S), "");
+  static_assert(__is_same(remove_reference<const volatile S &>, const volatile S), "");
+  static_assert(__is_same(remove_reference<const volatile S &&>, const volatile S), "");
+  static_assert(__is_same(remove_reference<int S::*const volatile &>, int S::*const volatile), "");
+  static_assert(__is_same(remove_reference<int (S::*const volatile &)()>, int(S::*const volatile)()), "");
+  static_assert(__is_same(remove_reference<int (S::*const volatile &&)() &>, int(S::*const volatile)() &), "");
 }
 
 template <class T> using remove_cvref_t = __remove_cvref(T);
 
 void check_remove_cvref() {
   static_assert(__is_same(remove_cvref_t<void>, void), "");
   static_assert(__is_same(remove_cvref_t<const volatile void>, void), "");
   static_assert(__is_same(remove_cvref_t<int>, int), "");