[ccache] Support for color diagnostics

[Joel Rosdahl]

Hi Lubos,

Sorry about the ping delay. I've now looked at your patch and it looks
promising.

The most immediate issue is this:

> % make -j4 test
> [...]
> test/main
> make: *** [test] Segmentation fault (core dumped)
> % gdb test/main core
> [...]
> Program terminated with signal SIGSEGV, Segmentation fault.
> #0  0x000000000040494a in compiler_is_clang () at ccache.c:1103
> 1103 const char* name = strrchr( orig_args->argv[ 0 ], '/' );
> (gdb) bt
> #0  0x000000000040494a in compiler_is_clang () at ccache.c:1103
> #1  0x0000000000408793 in cc_process_args (args=0x15dbf30,
preprocessor_args=0x7fffed5d75d8, compiler_args=0x7fffed5d75e0) at
ccache.c:2290
> #2  0x0000000000419f90 in suite_argument_processing (_start_point=1) at
test/test_argument_processing.c:68
> #3  0x0000000000417b40 in cct_run (suites=0x7fffed5d77f0,
verbose_output=0) at test/framework.c:72
> #4  0x0000000000417a50 in main (argc=1, argv=0x7fffed5d7938) at
test/main.c:86
> (gdb) p orig_args
> $1 = (struct args *) 0x0

I suggest passing the argument list as an argument to the compiler_is_*
functions instead of relying on global variables.

When extracting the compiler name, I suggest using basename() from util.c.
That way it will work on Windows as well.

-- Joel



On 1 June 2014 10:17, Lubos Lunak <l.lunak at centrum.cz> wrote:

> 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).
>
>  Ping? Any "official" comments on the patch? I've been using the patch for
> half a year by now without problems.
>
> >
> >  Clang automatically uses colors for output automatically if used in
> > terminal. Ccache's redirecting to a file disables this. GCC 4.8 has got a
> > similar support, except that it apparently requires also $GCC_COLORS or
> an
> > explicit option.
> >
> >  The patch detects if the compiler would use colors if used without
> ccache
> > and explicitly forces an option to achieve this. Note that I do not have
> > GCC 4.8 here, so I tested with Clang's alias and the GCC_COLORS support
> is
> > done based on documentation.
> >
> > Caveats:
> >
> > - GCC developers decided to roll their own name for the option when
> > introducing it. Clang has an alias for the GCC way, but versions
> predating
> > that obviously can't support it, so it's necessary to detect the
> compiler.
> > As ccache doesn't do that (and I don't find it worth much effort, as it
> > can't be 100% reliable anyway), the code merely guesses from the binary
> > name. If the compiler used will be e.g. the 'cc' symlink, there'll be no
> > colors. No big deal.
> >
> > - Since the stderr is different, obviously compiling with and without
> > colors has different results as well. That means that such a compile
> > is "duplicated". It's hopefully not such a common case, although it's
> > perfectly possible. I don't know if it's worth the effort to try to be
> > smart here. A possibly simple improvement could be to search the cache
> with
> > and without the option set and if stderr is empty, reuse the result
> > regardless of the option. I'm not quite sure where exactly this should
> > happen in the code.
> >
> >  I expect it'd make sense to add $CCACHE_NOCOLORS to disable this
> support?
> >
> >  I can also create manpage section for this color support, but I first
> > wanted to check here with the code.
>
> --
>  Lubos Lunak
>
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