Re: [PATCH] ARM: Don't define _SYS_AUXV_H in sysdep.h

["Joseph S. Myers" <joseph at codesourcery dot com>]

On Wed, 17 Sep 2014, Siddhesh Poyarekar wrote:

> On Tue, Sep 16, 2014 at 09:47:49PM +0000, Joseph S. Myers wrote:
> > Why does sysdep.h get included from these testcases anyway?  As well as 
> > moving away from defining _LIBC (and other internal defines) for tests 
> > unless needed for a particular test, it would also be good to move away 
> > from tests using the internal includes (if such an include is responsible 
> > here), instead making them use the versions of headers that actually get 
> > installed before looking for any other headers in the source tree or 
> > sysdeps directories.
> 
> I wonder if it would make sense to 'install' headers into a known
> location in the build directory during build and use only that for the
> tests.  That would make the tests completely isolated from the
> internal headers.  There are some tests that explicitly do white box
> testing; those can be treated as special cases.

Yes, headers should come from an installed staging directory for testing, 
but that's only part of the solution.

* Tests can quite reasonably have wrapper files for a given architecture 
in sysdeps, so you can't avoid the sysdeps search for everything.  (Most 
tests include at least one file that's not an installed header - 
test-skeleton.c.)  The installed headers should be searched before the 
sysdeps / other source tree headers, however.

* Tests should not include libc-symbols.h, or config.h, or get any of the 
defines from libc-symbols.h except _GNU_SOURCE (in particular, should not 
define _LIBC) unless there is a reason for them to do so.

* Such reasons may not be obvious simply from "test fails to build / work 
in a particular configuration".  E.g. tst-fanotify.c has a good reason to 
include config.h - it uses a configure test for whether linux/fanotify.h 
is available.  While it includes config.h explicitly, some tests might be 
relying on implicit includes.  So you need some way to search tests for 
references to config.h / libc-symbols.h symbols in #if conditions.

* Tests should also not get internal symbols defined in other ways.  The 
problem reported in the present case appears to be because of an 
_IO_MTSAFE_IO definition that resulted in various internal headers getting 
included.  That comes via CPPFLAGS += $(libio-mtsafe) in 
stdio-common/Makefile.

-- 
Joseph S. Myers
joseph@codesourcery.com