[Buildroot] [PATCH v2] infra/ccache: avoid color diagnostics with GCC older than v4.9

[Yann E. MORIN <yann.morin.1998@free.fr>]

Carlos, All,

On 2017-02-12 09:33 -0200, Carlos Santos spake thusly:
> Ensure that the GCC_COLORS environment variable is empty when calling
> ccache. When GCC_COLORS is set, ccache passes '-fdiagnostics-color' to
> GCC but this flag requires GCC v4.9 or later. Older versions complain
> about the unrecognized command line option.

So, while fixing my own patch about the issue [0], I noticed that I was
not even able to make it fail in the first place...

I'm using this defconfig, which uses a gcc-4.7:

    BR2_x86_i686=y
    BR2_CCACHE=y
    BR2_TOOLCHAIN_EXTERNAL=y

and Thomas reported he was also unable to reproduce the failure with:

    BR2_sh=y
    BR2_sh4a=y
    BR2_CCACHE=y
    BR2_TOOLCHAIN_EXTERNAL=y
    BR2_INIT_NONE=y
    BR2_SYSTEM_BIN_SH_NONE=y
    # BR2_PACKAGE_BUSYBOX is not set
    BR2_PACKAGE_DEVMEM2=y
    # BR2_TARGET_ROOTFS_TAR is not set

which also uses gcc-4.7.

Can you provide a reliable way to reproduce the issue, please?

Regards,
Yann E. MORIN.

> That behavior is hard-coded in ccache; we would need a patch to either
> make it optional or disable it at all. Notice also that the problem is
> not detectable in the autobuilders because they redirect the output to
> files/pipes and ccache adds the offending flag only when stderr is a
> terminal.
> 
> Signed-off-by: Carlos Santos <casantos@datacom.ind.br>
> ---
> Changes v1->v2
>   Fix indentation, use positive logic and improve the commit message,
>   acording to comments from Thomas Petazzoni and Yann E. MORIN.
> 
> Signed-off-by: Carlos Santos <casantos@datacom.ind.br>
> ---
>  package/Makefile.in | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/package/Makefile.in b/package/Makefile.in
> index 4a3eb26..e5e595a 100644
> --- a/package/Makefile.in
> +++ b/package/Makefile.in
> @@ -236,6 +236,13 @@ export PERL5LIB=$(HOST_DIR)/usr/lib/perl
>  
>  TARGET_MAKE_ENV = PATH=$(BR_PATH)
>  
> +# When GCC_COLORS is set, ccache passes '-fdiagnostics-color' to GCC but
> +# this flag requires GCC v4.9 or later. Older versions fail, complaining
> +# about unrecognized command line option.
> +ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_4_9),)
> +TARGET_MAKE_ENV += GCC_COLORS=""
> +endif
> +
>  TARGET_CONFIGURE_OPTS = \
>  	$(TARGET_MAKE_ENV) \
>  	AR="$(TARGET_AR)" \
> @@ -285,6 +292,11 @@ HOST_MAKE_ENV = \
>  	PKG_CONFIG_ALLOW_SYSTEM_LIBS=1 \
>  	PKG_CONFIG_LIBDIR="$(HOST_DIR)/usr/lib/pkgconfig:$(HOST_DIR)/usr/share/pkgconfig"
>  
> +# Prevent ccache from passing '-fdiagnostics-color' (see above).
> +ifeq ($(BR2_HOST_GCC_AT_LEAST_4_9),)
> +HOST_MAKE_ENV += GCC_COLORS=""
> +endif
> +
>  HOST_CONFIGURE_OPTS = \
>  	$(HOST_MAKE_ENV) \
>  	AR="$(HOSTAR)" \
> -- 
> 2.7.4
> 

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