No, it prevents *reading* of PCH files with -gstabs, so whatever you write
into the PCH file is uninteresting. The patch can surely be acompanied
by a patch to warn that writing a PCH file is useless in that case, as in
your patch, though the spot you chose for it is too early. Consider
./xgcc -B ./ -gstabs -o aa.h.gch aa.h -g0
Supposedly not do any testing if -g (defaulting to non-dwarf) or -gstabs
etc. are present in the default options (try to pre-compile some short
header first, if that fails with the newly added warning, punt),
drop all torture options using -g in it if such test fails with explicit
-g added from the list of torture options for testing, and perhaps add some
effective target if needed (valid-1.c test?).