Commit 5175cd77 authored by erichkeane's avatar erichkeane
Browse files

Disallow _BitInt as an underlying type for an enumeration 

As mentioned in #69619, C23 6.7.2.2p5 explicitly prohibits using a
_BitInt as an underlying type to an enumeration. While we had this in
the _ExtInt implementation, the justification for that limitation in C
is compelling, so this is being removed to be compatible with the C23
standard.

Fixes: #69619
parent 67770cbb

clang/docs/ReleaseNotes.rst

+3 −0
Original line number Diff line number Diff line
@@ -409,6 +409,9 @@ Bug Fixes in This Version 
  operator in C. No longer issuing a confusing diagnostic along the lines of

  "incompatible operand types ('foo' and 'foo')" with extensions such as matrix

  types. Fixes (`#69008 <https://github.com/llvm/llvm-project/issues/69008>`_)

- Clang no longer permits using the `_BitInt` types as an underlying type for an

  enumeration as specified in the C23 Standard.

  Fixes (`#69619 <https://github.com/llvm/llvm-project/issues/69619>`_)



Bug Fixes to Compiler Builtins

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

clang/include/clang/Basic/DiagnosticSemaKinds.td

+1 −1
Original line number Diff line number Diff line
@@ -2613,7 +2613,7 @@ def err_final_function_overridden : Error< 














// C++11 scoped enumerations















def err_enum_invalid_underlying : Error<













  "non-integral type %0 is an invalid underlying type">;













  "%select{non-integral type %0|%0}1 is an invalid underlying type">;















def err_enumerator_too_large : Error<















  "enumerator value is not representable in the underlying type %0">;















def ext_enumerator_too_large : Extension<

































clang/lib/Sema/SemaDecl.cpp



+2
−4






























Original line number
Diff line number
Diff line








@@ -16722,10 +16722,8 @@ bool Sema::CheckEnumUnderlyingType(TypeSourceInfo *TI) {













    if (BT->isInteger())















      return false;



























  if (T->isBitIntType())













    return false;

























  return Diag(UnderlyingLoc, diag::err_enum_invalid_underlying) << T;













  return Diag(UnderlyingLoc, diag::err_enum_invalid_underlying)













         << T << T->isBitIntType();















}





























/// Check whether this is a valid redeclaration of a previous enumeration.

























clang/test/CodeGenCXX/ext-int.cpp



+0
−13






























Original line number
Diff line number
Diff line








@@ -98,19 +98,6 @@ void BitfieldAssignment() {













  // CHECK: %[[SETC:.+]] = or i8 %[[CLEARC]], 64















}





























enum AsEnumUnderlyingType : _BitInt(9) {













  A,B,C













};



























void UnderlyingTypeUsage(AsEnumUnderlyingType Param) {













  // LIN: define{{.*}} void @_Z19UnderlyingTypeUsage20AsEnumUnderlyingType(i9 signext %













  // WIN64: define dso_local void @"?UnderlyingTypeUsage@@YAXW4AsEnumUnderlyingType@@@Z"(i9 %













  // WIN32: define dso_local void @"?UnderlyingTypeUsage@@YAXW4AsEnumUnderlyingType@@@Z"(i9 signext %













  AsEnumUnderlyingType Var;













  // CHECK: alloca i9, align 2













  // CHECK: store i9 %{{.*}}, align 2













}





























unsigned _BitInt(33) ManglingTestRetParam(unsigned _BitInt(33) Param) {















// LIN64: define{{.*}} i64 @_Z20ManglingTestRetParamDU33_(i64 %















// LIN32: define{{.*}} i33 @_Z20ManglingTestRetParamDU33_(i33 %

































clang/test/SemaCXX/ext-int.cpp



+2
−2






























Original line number
Diff line number
Diff line








@@ -211,8 +211,8 @@ void ConstexprBitsize() {













  static_assert(is_same<decltype(F), _BitInt(42)>::value, "");















}





























// Useable as an underlying type.













enum AsEnumUnderlyingType : _BitInt(33) {













// Not useable as an underlying type.













enum AsEnumUnderlyingType : _BitInt(33) { // expected-error{{'_BitInt(33)' is an invalid underlying type}}















};































void overloaded(int);