CFLAGS only for clang in mixed-compiler project?

[Ian Lepore]

On Thu, 2015-01-01 at 19:01 +0300, Lev Serebryakov wrote:
>  I'm trying to update arm-eabi (microcontroller) cross-gcc port to
> latest version 4.9 and have one weird problem.
> 
>  Some part of gcc for arm (neon coprocessor machine description, to be
> precise) requires more than 256 nested parenthesis in version 4.9 (4.8
> doesn't have this problem). Due to this parenthesis madness clang
> needs "-fbracket-depth=1024" option. If I add this option to CFLAGS in
> environment variable, I have other problem. Later in build process gcc
> uses newly-built gcc (xgcc) to build library. And this gcc picks up
> "-fbracket-depth=1024" from environment and fails due to unknown option!
> 
>  How could I provide options only for clang but not for gcc?

Don't set it in the env, set it in a make variable.  The
devel/arm-none-eabi-gcc port (which builds a bare-metal arm cross
compiler and may be exactly what you need) has this:

.include <bsd.port.options.mk>

# The following is required for clang to bootstrap gcc.
.if ${COMPILER_TYPE} == clang
MAKE_ARGS+=	CXXFLAGS=-fbracket-depth=512
.endif

-- Ian