[gcc r14-6041] doc: Update the status of build directory not fully separated

[Xi Ruoyao]

https://gcc.gnu.org/g:875c7771097d12f81f658f5f01ef52ec5b57f678

commit r14-6041-g875c7771097d12f81f658f5f01ef52ec5b57f678
Author: Xi Ruoyao <xry111@xry111.site>
Date:   Thu Nov 30 17:35:10 2023 +0800

    doc: Update the status of build directory not fully separated
    
    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.

Diff:
---
 gcc/doc/install.texi | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index c1ccb8ba02d..c1128d9274c 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -697,9 +697,8 @@ phases.
 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