[cfe-dev] Clang and llvm-gcc disagree on my wrong code

[Peter Collingbourne]

On Wed, Dec 15, 2010 at 10:37:58AM -0800, Jakob Stoklund Olesen wrote:
> Hi,
> 
> I just broke the build by committing essentially this function:
> 
> #include <vector>
> void f() {
>   std::vector<int> v;
>   while (!v.empty) // <-- Note missing ()
>     v.pop_back();
> }
> 
> Clang happily and silently compiled this into:
> 
> while.cond:
>   br i1 false, label %while.body, label %while.end
> 
> GCC doesn't like the bad code at all:
> 
> $ llvm-g++ test.cpp
> test.cpp: In function ‘void f()’:
> test.cpp:4: error: could not convert ‘v.std::vector<_Tp, _Alloc>::empty [with _Tp = int, _Alloc = std::allocator<int>]’ to ‘bool’
> test.cpp:4: error: in argument to unary !
> 
> Who is right?

GCC is right here.

>From C++2003 [expr.ref](4):

"The expression can only be used as a left-hand operand of a member
function call."

I attached a much simpler test case.  So the problem is the unary "!"
operator, which should reject MemberExprs which refer to non-static
member functions.

Please open a bug report.

Thanks,
-- 
Peter
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