[patch] Use a more idiomatic bool operator in ErrorOr

[Alp Toker]

On 16/01/2014 18:20, Aaron Ballman wrote:
> On Thu, Jan 16, 2014 at 1:13 PM, Alp Toker <alp at nuanti.com> wrote:
>> On 16/01/2014 18:05, Reid Kleckner wrote:
>>> With the impending switch to C++11, feel free to cleanup instances of this
>>> safe bool idiom.
>>
>> Very unfortunate news on that front: explicit operators aren't support until
>> MSVC 2013.
>>
>>    http://msdn.microsoft.com/en-us/library/hh567368.aspx
>>
>> That means LLVM_EXPLICIT will still be defined to nothing on MSVC 2012,
>> resulting in inappropriate conversions taking precedence over the bool
>> operator.
> At least the 2013 build bot will still catch problems if it's misused,
> but good point about using the compatibility macro.

Yes, I switched it on for MSVC 2013 back in r198142, along with updates 
to the other macros.

That said, the current setup is a little dangerous and the only fully 
safe use I can see of the macro is for the benefit of sub-projects that 
have already pushed ahead and dropped MSVC 2012.

In common use when the macro is turned off it's entirely possible an int 
conversion will silently be chosen leading to runtime brokenness :-/

Perhaps we should document this. Thoughts?

Alp.


-- 
http://www.nuanti.com
the browser experts