[cairo] [PATCH 2/4] configure.ac: Explicitly enable subject-objects for automake 1.11

[Uli Schlachter]

On 09.07.2014 03:13, Bryce W. Harrington wrote:
> This fixes this build issue on Ubuntu 14.04 with gcc 4.8:
> 
> perf/Makefile.sources:7: warning: source file '../src/cairo-time.c' is in a subdirectory,
> perf/Makefile.sources:7: but option 'subdir-objects' is disabled
> perf/Makefile.am:3:   'perf/Makefile.sources' included from here
> automake: warning: possible forward-incompatibility.
> automake: At least a source file is in a subdirectory, but the 'subdir-objects'
> automake: automake option hasn't been enabled.  For now, the corresponding output
> automake: object file(s) will be placed in the top-level directory.  However,
> automake: this behaviour will change in future Automake versions: they will
> automake: unconditionally cause object files to be placed in the same subdirectory
> automake: of the corresponding sources.
> automake: You are advised to start using 'subdir-objects' option throughout your
> automake: project, to avoid future incompatibilities.

So far, that's just a warning. However, I wonder if we really want this. Doesn't
this mean that both src/Makefile and perf/Makefile will try to create
src/cairo-time.lo (and the corresponding files in src/.libs/) and isn't it, in
theory, possible that one of them overwrites the files while the other is trying
to read it?

I guess that this is only a theoretical issue since perf/ depends on src/ in the
top-level Makefile (right?).

> Signed-off-by: Bryce Harrington <b.harrington at samsung.com>
> ---
>  configure.ac |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/configure.ac b/configure.ac
> index 66a8558..fca6fc5 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -13,7 +13,7 @@ AC_CONFIG_HEADERS(config.h)
>  
>  AC_CHECK_HEADERS([unistd.h sys/ioctl.h])
>  
> -AM_INIT_AUTOMAKE([1.11 foreign -Wall no-define no-dist-gzip dist-xz])
> +AM_INIT_AUTOMAKE([1.11 foreign -Wall no-define no-dist-gzip dist-xz subdir-objects])
>  AM_SILENT_RULES([yes])
>  m4_ifdef([AM_PROG_AR], [AM_PROG_AR]) dnl Workaround for Automake 1.11
>  
> 


-- 
"Why make things difficult, when it is possible to make them cryptic
and totally illogical, with just a little bit more effort?" -- A. P. J.