[PATCH] D98104: Update __is_unsigned builtin to match the Standard.

[Zoe Carver via Phabricator via cfe-commits]

zoecarver created this revision.
zoecarver added reviewers: ldionne, rsmith, tmatheson.
zoecarver requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

Updates __is_unsigned to have the same behavior as the standard
specifies. This is in line with 511dbd8, which applied the same change
to __is_signed.

Refs D67897 <https://reviews.llvm.org/D67897>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D98104

Files:
  clang/docs/LanguageExtensions.rst
  clang/lib/Sema/SemaExprCXX.cpp
  clang/test/SemaCXX/type-traits.cpp


Index: clang/test/SemaCXX/type-traits.cpp
===================================================================
--- clang/test/SemaCXX/type-traits.cpp
+++ clang/test/SemaCXX/type-traits.cpp
@@ -13,6 +13,7 @@
 // PODs
 enum Enum { EV };
 enum SignedEnum : signed int { };
+enum UnsignedEnum : unsigned int { };
 struct POD { Enum e; int i; float f; NonPOD* p; };
 struct Empty {};
 struct IncompleteStruct;
@@ -1450,7 +1451,6 @@
   int t04[T(__is_unsigned(unsigned int))];
   int t05[T(__is_unsigned(unsigned long))];
   int t06[T(__is_unsigned(unsigned long long))];
-  int t07[T(__is_unsigned(Enum))];
 
   int t10[F(__is_unsigned(void))];
   int t11[F(__is_unsigned(cvoid))];
@@ -1468,6 +1468,8 @@
   int t24[F(__is_unsigned(Derives))];
   int t25[F(__is_unsigned(ClassType))];
   int t26[F(__is_unsigned(IntArNB))];
+  int t27[F(__is_unsigned(Enum))];
+  int t28[F(__is_unsigned(UnsignedEnum))];
 }
 
 typedef Int& IntRef;
Index: clang/lib/Sema/SemaExprCXX.cpp
===================================================================
--- clang/lib/Sema/SemaExprCXX.cpp
+++ clang/lib/Sema/SemaExprCXX.cpp
@@ -4833,7 +4833,8 @@
     // Floating points should always return true.
     return !T->isEnumeralType() && (T->isFloatingType() || T->isSignedIntegerType());
   case UTT_IsUnsigned:
-    return T->isUnsignedIntegerType();
+    // Enum types should always return false (same as UTT_IsSigned).
+    return !T->isEnumeralType() && T->isUnsignedIntegerType();
 
     // Type trait expressions which query classes regarding their construction,
     // destruction, and copying. Rather than being based directly on the
Index: clang/docs/LanguageExtensions.rst
===================================================================
--- clang/docs/LanguageExtensions.rst
+++ clang/docs/LanguageExtensions.rst
@@ -1194,7 +1194,9 @@
 * ``__is_sealed`` (Microsoft):
   Synonym for ``__is_final``.
 * ``__is_signed`` (C++, Embarcadero):
-  Returns false for enumeration types, and returns true for floating-point types. Note, before Clang 10, returned true for enumeration types if the underlying type was signed, and returned false for floating-point types.
+  Returns false for enumeration types, and returns true for floating-point
+  types. Note, before Clang 10, returned true for enumeration types if the
+  underlying type was signed, and returned false for floating-point types.
 * ``__is_standard_layout`` (C++, GNU, Microsoft, Embarcadero)
 * ``__is_trivial`` (C++, GNU, Microsoft, Embarcadero)
 * ``__is_trivially_assignable`` (C++, GNU, Microsoft)
@@ -1203,9 +1205,8 @@
 * ``__is_trivially_destructible`` (C++, MSVC 2013)
 * ``__is_union`` (C++, GNU, Microsoft, Embarcadero)
 * ``__is_unsigned`` (C++, Embarcadero)
-  Note that this currently returns true for enumeration types if the underlying
-  type is unsigned, in violation of the requirements for ``std::is_unsigned``.
-  This behavior is likely to change in a future version of Clang.
+  Returns false for enumeration types. Note, before Clang 13, returned true for
+  enumeration types if the underlying type was unsigned.
 * ``__is_void`` (C++, Embarcadero)
 * ``__is_volatile`` (C++, Embarcadero)
 * ``__reference_binds_to_temporary(T, U)`` (Clang):  Determines whether a


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