[ccache] Support for color diagnostics

[Loïc Yhuel]

Le 29/11/2013 14:08, Lubos Lunak a écrit :
> On Friday 29 of November 2013, Lubos Lunak wrote:
>>   Hello,
>>
>>   the attached patch adds ccache support for compiler color diagnostics
>> (also reported by somebody as #10075).
> ...
>> Caveats:
>   I forgot one:
>
> - The function color_output_possible() may look simplistic, but as far as I
> can tell it works just fine (it's been in Incecream for a number of years).
>
Hello,

I think you didn't understand GCC documentation correctly.

 From the man page : "The default GCC_COLORS is ... Setting GCC_COLORS 
to the empty string disables colors."
GCC enable colors when GCC_COLORS is not set, and your code doesn't.

In fact you don't have to test GCC_COLORS at all : when it's an empty 
string (not unset !), colors are disabled , and adding 
-fdiagnostics-color doesn't change anything.