Re: RFC: introduce common.m4

[Pedro Alves <palves at redhat dot com>]

On 04/24/2013 06:30 PM, Tom Tromey wrote:
> It has bothered me for a while that files in common/ use macros
> defined via autoconf checks, but rely on each configure.ac doing the
> proper checks independently.
> 
> This patch introduces common/common.m4 which consolidates the checks
> assumed by code in common.
> 
> The rule I propose is that if something is needed or used by common,
> it should be checked for by common.m4; but that code outside this
> directory also be free to use these results.  This means that removing
> checks from common.m4 must first be preceded by looking at uses in gdb
> and gdbserver.  I think this is pretty easy to do -- easier than what
> we are doing now -- and I have documented the requirement.

What's the advantage of doing it this way?  Caching?  Doesn't autoconf
use the cached value if there are multiple AC_CHECK_FOOs for the same
thing?  Not super sure I like this over keeping each directory aware
of its dependencies, but I suppose I can go along.

> This process revealed a few things not checked for in gdbserver
> (nothing too crucial I think) and also that the decl check for getopt
> was dead.

Ah, an "also".  ;-)

> I wrote GDB_AC_COMMON by looking for HAVE_ symbols in common/*.[ch].
> I did not look for library dependencies, so it is possible that
> something is missing.  I think it is worthwhile to have this in place
> now, even if it is not perfect, because it gives us a place to make
> future improvements.

I definitely agree with the idea of a common common.m4 in common/. :-)

> gdb:
> 	* acinclude.m4: Include common.m4.
> 	* common/common.m4: New file.
> 	* configure, config.in: Rebuild.
> 	* configure: Move some checks to common.m4.  Use GDB_AC_COMMON.

s/configure/configure.ac/


> 
> gdbserver:
> 	* acinclude.m4: Include common.m4, codeset.m4.

codeset.m4?

> 	* configure, config.in: Rebuild.
> 	* configure: Move some checks to common.m4.  Use GDB_AC_COMMON.

s/configure/configure.ac/


> +  AC_CHECK_HEADERS(linux/perf_event.h locale.h memory.h signal.h dnl
> +                   string.h strings.h sys/resource.h sys/un.h sys/wait.h dnl
> +		   thread_db.h wait.h)

Something odd with indentation here.

Mechanically looks good to me.  I don't plan on
checking/cross-checking what was moved in detail.

-- 
Pedro Alves