[GRASS-dev] [GRASS GIS] #2916: configure bug (?): FORTIFY_SOURCE in CPPFLAGS breaks configure on Arch Linux

[GRASS GIS]

#2916: configure bug (?): FORTIFY_SOURCE in CPPFLAGS breaks configure on Arch
Linux
------------------------+-------------------------
  Reporter:  msieczka   |      Owner:  grass-dev@…
      Type:  defect     |     Status:  new
  Priority:  normal     |  Milestone:  7.0.4
 Component:  Compiling  |    Version:  7.0.3
Resolution:             |   Keywords:
       CPU:  All        |   Platform:  Linux
------------------------+-------------------------

Comment (by glynn):

 Replying to [comment:10 msieczka]:

 > Thanks for the explanation. Do you know why this "_FORTIFY_SOURCE
 requires compiling with optimization (-O)" warning is triggered? I think
 it shouldn't be, because I do have optimization enabled in my build
 environment:

 Optimisation switches are normally in CFLAGS or CXXFLAGS, while -D
 switches are normally in CPPFLAGS. The configure checks for the
 preprocessor don't pass $(CFLAGS) or $(CXXFLAGS) because most of the
 switches that they're likely to contain often aren't recognised by a
 standalone preprocessor, and may result in an error. The comment in
 autoconf/c.m4 says:
 {{{
 # CFLAGS is not in ac_cpp because -g, -O, etc. are not valid cpp options.
 }}}

 Apart from that, there are valid reasons for compiling without
 optimisation (e.g. it often makes debugging significantly more difficult),
 so forcibly enabling _FORTIFY_SOURCE doesn't appear to have been a
 particularly wise move.

 FWIW, on Gentoo this is implemented within the compiler:
 {{{
 $ gcc -E -dM -O2 -x c /dev/null | fgrep FORTIFY
 #define _FORTIFY_SOURCE ((defined __OPTIMIZE__ && __OPTIMIZE__ > 0) ? 2 :
 0)
 }}}
 I.e. _FORTIFY_SOURCE is enabled automatically if and only if optimisation
 is enabled.

 As for workarounds, the simplest to implement would be to have
 configure.in check whether $(CPPFLAGS) contains -D_FORTIFY_SOURCE and
 either attempt to remove it or generate an error telling the user to
 remove it. It can always be added to CFLAGS and/or CXXFLAGS.

--
Ticket URL: <http://trac.osgeo.org/grass/ticket/2916#comment:11>
GRASS GIS <https://grass.osgeo.org>