[cfe-commits] r148874 - in /cfe/trunk: lib/Sema/SemaExprCXX.cpp test/Analysis/reference.cpp

[Nico Weber]

Hi Eli,

with this change, clang now warns about this function in gtest (which is fine):

// Invalid<T>() returns an invalid value of type T.  This is useful
// when a value of type T is needed for compilation, but the statement
// will not really be executed (or we don't care if the statement
// crashes).
template <typename T>
inline T Invalid() {
  return *static_cast<typename remove_reference<T>::type*>(NULL);
}

The warning recommends to add a "volatile", but then code that calls
this function with a type without copy constructor fails to compile.
What's the recommended way to change code like this?

Should the -Wnull-dereference diagnostic text be changed to something
else in an expression context? It currently says "consider using
__builtin_trap() or qualifying pointer with 'volatile'".

Thanks,
Nico

On Tue, Jan 24, 2012 at 2:51 PM, Eli Friedman <eli.friedman at gmail.com> wrote:
> Author: efriedma
> Date: Tue Jan 24 16:51:26 2012
> New Revision: 148874
>
> URL: http://llvm.org/viewvc/llvm-project?rev=148874&view=rev
> Log:
> Switch PerformImplicitConversion over to use DefaultLvalueConversion for lvalue-to-rvalue conversion.
>
>
> Modified:
>    cfe/trunk/lib/Sema/SemaExprCXX.cpp
>    cfe/trunk/test/Analysis/reference.cpp
>
> Modified: cfe/trunk/lib/Sema/SemaExprCXX.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExprCXX.cpp?rev=148874&r1=148873&r2=148874&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaExprCXX.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaExprCXX.cpp Tue Jan 24 16:51:26 2012
> @@ -2324,12 +2324,14 @@
>     // Nothing to do.
>     break;
>
> -  case ICK_Lvalue_To_Rvalue:
> +  case ICK_Lvalue_To_Rvalue: {
>     assert(From->getObjectKind() != OK_ObjCProperty);
>     FromType = FromType.getUnqualifiedType();
> -    From = ImplicitCastExpr::Create(Context, FromType, CK_LValueToRValue,
> -                                    From, 0, VK_RValue);
> +    ExprResult FromRes = DefaultLvalueConversion(From);
> +    assert(!FromRes.isInvalid() && "Can't perform deduced conversion?!");
> +    From = FromRes.take();
>     break;
> +  }
>
>   case ICK_Array_To_Pointer:
>     FromType = Context.getArrayDecayedType(FromType);
>
> Modified: cfe/trunk/test/Analysis/reference.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/reference.cpp?rev=148874&r1=148873&r2=148874&view=diff
> ==============================================================================
> --- cfe/trunk/test/Analysis/reference.cpp (original)
> +++ cfe/trunk/test/Analysis/reference.cpp Tue Jan 24 16:51:26 2012
> @@ -1,4 +1,4 @@
> -// RUN: %clang_cc1 -analyze -analyzer-checker=core,experimental.core -analyzer-store=region -analyzer-constraints=range -verify %s
> +// RUN: %clang_cc1 -analyze -analyzer-checker=core,experimental.core -analyzer-store=region -analyzer-constraints=range -verify -Wno-null-dereference %s
>  // XFAIL
>
>  typedef typeof(sizeof(int)) size_t;
>
>
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