Re: Per-machine additions to CFLAGS-rtld.c being overridden.

[Mike Frysinger <vapier at gentoo dot org>]

On 09 Jan 2013 18:03, Roland McGrath wrote:
> There are several layers here.

since this is 3 years old, full thread can be found starting here:
https://sourceware.org/ml/libc-alpha/2013-01/msg00247.html

> * Using per-file (or per-directory) *FLAGS settings is always the worst
>   option.  Not only is it obscure and easily overlooked, it doesn't get
>   tracked as a dependency to recompile things as needed.  We should avoid
>   it whenever possible.
> 
>   If it's used for things like -D switches there is just no excuse.	
>   That can be done with wrapper source files in sysdeps instead.
> 
>   When it's used for code-generation options, it can't really be avoided at
>   the moment.  One day the GCC pragma/attribute features for embedding such
>   options directly in the sources will be complete and we'll require
>   building libc with a GCC new enough to support all that.  But that will
>   be a long time off.

this seems to be in disagreement with GNU standards where you can do
`make bindir=...` and have the path be used (rather than the one set
at configure time).  ignoring that, it's the only real sane way to
fully expand the path because the path could be nested in other vars.
e.g. something like:
	prefix=/usr
	exec_prefix=$prefix
	bindir=$exec_prefix

specifically, we're talking about:
elf/Makefile:
SYSCONF-FLAGS := -D'SYSCONFDIR="$(sysconfdir)"'
CFLAGS-ldconfig.c = $(SYSCONF-FLAGS) -D'LIBDIR="$(libdir)"' -D'SLIBDIR="$(slibdir)"'
libof-ldconfig = ldconfig
CFLAGS-dl-cache.c = $(SYSCONF-FLAGS)
CFLAGS-cache.c = $(SYSCONF-FLAGS)
CFLAGS-rtld.c += $(SYSCONF-FLAGS)

do we want to move these -D flags to Makeconfig's CPPFLAGS ?
and do it for all the path related variables ?  it would make
the command line blow up a bit ... but then we wouldn't have
per-file or per-dir settings in more places.
-mike

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