[clang] [Clang] Remove __is_nullptr (PR #99038)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Nikolas Klauser (philnik777)

<details>
<summary>Changes</summary>

`is_null_pointer` can be implemented very efficiently as `__is_same(__remove_cv(T), decltype(nullptr))`. Since GCC supports both of these builtins as well, libc++ has no interest in using `__is_nullptr` instead. Furthermore, I could find only a single use in the wild (https://sourcegraph.com/search?q=context:global+__is_nullptr%28+-file:clang&patternType=keyword&sm=0). Because of these reasons I don't think it's worth keeping this builtin around.


---
Full diff: https://github.com/llvm/llvm-project/pull/99038.diff


5 Files Affected:

- (modified) clang/docs/LanguageExtensions.rst (-4) 
- (modified) clang/lib/Parse/ParseDeclCXX.cpp (+2-3) 
- (modified) clang/lib/Parse/ParseExpr.cpp (-1) 
- (modified) clang/lib/Sema/SemaExprCXX.cpp (-3) 
- (modified) clang/test/SemaCXX/type-traits.cpp (-36) 


``````````diff
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index 81784c75081ba..cfd7d29fb9eac 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -1614,10 +1614,6 @@ The following type trait primitives are supported by Clang. Those traits marked
 * ``__is_nothrow_assignable`` (C++, MSVC 2013)
 * ``__is_nothrow_constructible`` (C++, MSVC 2013)
 * ``__is_nothrow_destructible`` (C++, MSVC 2013)
-* ``__is_nullptr`` (C++, GNU, Microsoft, Embarcadero):
-  Returns true for ``std::nullptr_t`` and false for everything else. The
-  corresponding standard library feature is ``std::is_null_pointer``, but
-  ``__is_null_pointer`` is already in use by some implementations.
 * ``__is_object`` (C++, Embarcadero)
 * ``__is_pod`` (C++, GNU, Microsoft, Embarcadero):
   Note, the corresponding standard trait was deprecated in C++20.
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index ce827c689beb7..2c201d346328b 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -447,9 +447,9 @@ Decl *Parser::ParseLinkage(ParsingDeclSpec &DS, DeclaratorContext Context) {
 ///
 /// HLSL: Parse export function declaration.
 ///
-///      export-function-declaration: 
+///      export-function-declaration:
 ///         'export' function-declaration
-/// 
+///
 ///      export-declaration-group:
 ///         'export' '{' function-declaration-seq[opt] '}'
 ///
@@ -1799,7 +1799,6 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
           tok::kw___is_nothrow_constructible,
           tok::kw___is_nothrow_convertible,
           tok::kw___is_nothrow_destructible,
-          tok::kw___is_nullptr,
           tok::kw___is_object,
           tok::kw___is_pod,
           tok::kw___is_pointer,
diff --git a/clang/lib/Parse/ParseExpr.cpp b/clang/lib/Parse/ParseExpr.cpp
index 3d7c58e5b3c3c..b3df9cfbc8b9a 100644
--- a/clang/lib/Parse/ParseExpr.cpp
+++ b/clang/lib/Parse/ParseExpr.cpp
@@ -800,7 +800,6 @@ bool Parser::isRevertibleTypeTrait(const IdentifierInfo *II,
     REVERTIBLE_TYPE_TRAIT(__is_nothrow_assignable);
     REVERTIBLE_TYPE_TRAIT(__is_nothrow_constructible);
     REVERTIBLE_TYPE_TRAIT(__is_nothrow_destructible);
-    REVERTIBLE_TYPE_TRAIT(__is_nullptr);
     REVERTIBLE_TYPE_TRAIT(__is_object);
     REVERTIBLE_TYPE_TRAIT(__is_pod);
     REVERTIBLE_TYPE_TRAIT(__is_pointer);
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index bef7da239e6e5..a41b938531cab 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -4979,7 +4979,6 @@ static bool CheckUnaryTypeTraitTypeCompleteness(Sema &S, TypeTrait UTT,
   case UTT_IsArray:
   case UTT_IsBoundedArray:
   case UTT_IsPointer:
-  case UTT_IsNullPointer:
   case UTT_IsReferenceable:
   case UTT_IsLvalueReference:
   case UTT_IsRvalueReference:
@@ -5235,8 +5234,6 @@ static bool EvaluateUnaryTypeTrait(Sema &Self, TypeTrait UTT,
     return T->isIncompleteArrayType();
   case UTT_IsPointer:
     return T->isAnyPointerType();
-  case UTT_IsNullPointer:
-    return T->isNullPtrType();
   case UTT_IsLvalueReference:
     return T->isLValueReferenceType();
   case UTT_IsRvalueReference:
diff --git a/clang/test/SemaCXX/type-traits.cpp b/clang/test/SemaCXX/type-traits.cpp
index 7adbf4aad7afe..b38e8989cb559 100644
--- a/clang/test/SemaCXX/type-traits.cpp
+++ b/clang/test/SemaCXX/type-traits.cpp
@@ -1041,42 +1041,6 @@ void is_pointer()
   static_assert(!__is_pointer(void (StructWithMembers::*) ()));
 }
 
-void is_null_pointer() {
-  StructWithMembers x;
-
-  static_assert(__is_nullptr(decltype(nullptr)));
-  static_assert(!__is_nullptr(void *));
-  static_assert(!__is_nullptr(cvoid *));
-  static_assert(!__is_nullptr(cvoid *));
-  static_assert(!__is_nullptr(char *));
-  static_assert(!__is_nullptr(int *));
-  static_assert(!__is_nullptr(int **));
-  static_assert(!__is_nullptr(ClassType *));
-  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(void (*)()));
-
-  static_assert(!__is_nullptr(void));
-  static_assert(!__is_nullptr(cvoid));
-  static_assert(!__is_nullptr(cvoid));
-  static_assert(!__is_nullptr(char));
-  static_assert(!__is_nullptr(int));
-  static_assert(!__is_nullptr(int));
-  static_assert(!__is_nullptr(ClassType));
-  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::*)()));
-}
-
 void is_member_object_pointer()
 {
   StructWithMembers x;

``````````

</details>


https://github.com/llvm/llvm-project/pull/99038