Recently there are some people building GCC with srcdir == objdir and
the attempts just failed [1]. So stop to say "it should work". OTOH
objdir as a subdirectory of srcdir works: we've built GCC in LFS [2]
and BLFS [3] this way for decades and this is confirmed during the
review of a previous version of this patch [4].
[1]: https://gcc.gnu.org/pipermail/gcc-help/2023-November/143068.html
[2]: https://www.linuxfromscratch.org/lfs/view/12.0/chapter08/gcc.html
[3]: https://www.linuxfromscratch.org/blfs/view/12.0/general/gcc.html
[4]: https://gcc.gnu.org/pipermail/gcc-patches/2023-November/638760.html
gcc/ChangeLog:
* doc/install.texi: Deem srcdir == objdir broken, but objdir
as a subdirectory of srcdir fine.
First, we @strong{highly} recommend that GCC be built into a
separate directory from the sources which does @strong{not} reside
within the source tree. This is how we generally build GCC; building
-where @var{srcdir} == @var{objdir} should still work, but doesn't
-get extensive testing; building where @var{objdir} is a subdirectory
-of @var{srcdir} is unsupported.
+where @var{objdir} is a subdirectory of @var{srcdir} should work as well;
+building where @var{objdir} == @var{srcdir} is unsupported.
If you have previously built GCC in the same directory for a
different target machine, do @samp{make distclean} to delete all files