[Bug driver/48524] spec language does not cover switches with separated form

["joseph at codesourcery dot com" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48524

--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot com> 2011-04-09 11:28:33 UTC ---
Specs are an internal GCC implementation detail, subject to change 
whenever convenient for implementation purposes.  (Whoever put 
documentation for them in invoke.texi was wrong to do so - and as far as I 
know, did not have FSF permission either for copying text from gcc.c under 
one license to invoke.texi under another - the comment starting "Specs are 
strings containing lines" is the proper documentation for specs.)  My 
recommendation in 
<http://gcc.gnu.org/ml/gcc-patches/2011-02/msg01486.html> for certain 
broken -D specs in GCC was that any required semantics should be moved 
into cc1.  We have for a long time been moving away from defining built-in 
macros in specs, towards defining them based on actual logical state 
derived from option processing.  In any case if you wish to submit a patch 
for some new specs feature I would suggest you include the 
--enable-fortify-source=2 or similar configure option with it to provide 
some actual use for that feature in GCC.  Note that the spec you give 
appears wrong in that any -D_FORTIFY_SOURCE or -D_FORTIFY_SOURCE=<value> 
option passed by the user should presumably also disable a default 
-D_FORTIFY_SOURCE=2 option; maybe you actually want an 
if-macro-not-defined spec function that covers all these cases.