r239170 - [AST] There is no message for C++1z-style static_assert

[Richard Smith]

On Fri, Jun 5, 2015 at 11:03 AM, David Majnemer <david.majnemer at gmail.com>
wrote:

> Author: majnemer
> Date: Fri Jun  5 13:03:58 2015
> New Revision: 239170
>
> URL: http://llvm.org/viewvc/llvm-project?rev=239170&view=rev
> Log:
> [AST] There is no message for C++1z-style static_assert
>
> We would crash in the DeclPrinter trying to pretty-print the
> static_assert message.  C++1z-style assertions don't have a message so
> we would crash.
>
> This fixes PR23756.
>
> Modified:
>     cfe/trunk/lib/AST/DeclPrinter.cpp
>     cfe/trunk/lib/Headers/Intrin.h
>     cfe/trunk/test/SemaCXX/static-assert.cpp
>
> Modified: cfe/trunk/lib/AST/DeclPrinter.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/DeclPrinter.cpp?rev=239170&r1=239169&r2=239170&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/AST/DeclPrinter.cpp (original)
> +++ cfe/trunk/lib/AST/DeclPrinter.cpp Fri Jun  5 13:03:58 2015
> @@ -733,8 +733,10 @@ void DeclPrinter::VisitImportDecl(Import
>  void DeclPrinter::VisitStaticAssertDecl(StaticAssertDecl *D) {
>    Out << "static_assert(";
>    D->getAssertExpr()->printPretty(Out, nullptr, Policy, Indentation);
> -  Out << ", ";
> -  D->getMessage()->printPretty(Out, nullptr, Policy, Indentation);
> +  if (StringLiteral *SL = D->getMessage()) {
> +    Out << ", ";
> +    SL->printPretty(Out, nullptr, Policy, Indentation);
> +  }
>    Out << ")";
>  }
>
>
> Modified: cfe/trunk/lib/Headers/Intrin.h
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Headers/Intrin.h?rev=239170&r1=239169&r2=239170&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Headers/Intrin.h (original)
> +++ cfe/trunk/lib/Headers/Intrin.h Fri Jun  5 13:03:58 2015
> @@ -546,13 +546,8 @@ _bittestandset(long *a, long b) {
>  #if defined(__i386__) || defined(__x86_64__)
>  static __inline__ unsigned char __attribute__((__always_inline__,
> __nodebug__))
>  _interlockedbittestandset(long volatile *__BitBase, long __BitPos) {
> -  unsigned char __Res;
> -  __asm__ ("xor %0, %0\n"
> -           "lock bts %2, %1\n"
> -           "setc %0\n"
> -           : "=r" (__Res), "+m"(*__BitBase)
> -           : "Ir"(__BitPos));
> -  return __Res;
> +  long __OldVal = __atomic_fetch_or(__BitBase, 1 << __BitPos, 5);
> +  return (__OldVal >> __BitPos) & 1;
>  }
>  #endif
>  #ifdef __x86_64__
>
> Modified: cfe/trunk/test/SemaCXX/static-assert.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/static-assert.cpp?rev=239170&r1=239169&r2=239170&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/SemaCXX/static-assert.cpp (original)
> +++ cfe/trunk/test/SemaCXX/static-assert.cpp Fri Jun  5 13:03:58 2015
> @@ -51,3 +51,12 @@ StaticAssertProtected<X> sap2; // expect
>
>  static_assert(true); // expected-warning {{C++1z extension}}
>  static_assert(false); // expected-error-re {{failed{{$}}}}
> expected-warning {{extension}}
> +
> +void PR23756() {
> +  struct { // expected-note 2 {{no known conversion from}}
> +  } _ = decltype(            // expected-error {{no viable conversion}}
> +      ({                     // expected-warning {{no effect in an
> unevaluated context}}
> +        static_assert(true); // expected-warning {{C++1z extension}}
> +        1;
> +      })){};
> +}


Can you add a pretty-printer test rather than relying on the diagnostics
engine pretty-printing the expression within a 'decltype' here? I'm
thinking we shouldn't pretty-print the operand of 'decltype' when printing
the type...
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