[Bug bootstrap/25672] [4.6/4.7/4.8 Regression] cross build's libgcc picks up CFLAGS

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25672

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jsm28 at gcc dot gnu.org

--- Comment #33 from Richard Biener <rguenth at gcc dot gnu.org> 2013-01-15 15:02:54 UTC ---
Re-confirmed on the 4.7 branch.  configury now has

# During gcc bootstrap, if we use some random cc for stage1 then CFLAGS
# might be empty or "-g".  We don't require a C++ compiler, so CXXFLAGS
# might also be empty (or "-g", if a non-GCC C++ compiler is in the path).
# We want to ensure that TARGET libraries (which we know are built with
# gcc) are built with "-O2 -g", so include those options when setting
# CFLAGS_FOR_TARGET and CXXFLAGS_FOR_TARGET.
if test "x$CFLAGS_FOR_TARGET" = x; then
  CFLAGS_FOR_TARGET=$CFLAGS
  case " $CFLAGS " in
    *" -O2 "*) ;;
    *) CFLAGS_FOR_TARGET="-O2 $CFLAGS" ;;
  esac
  case " $CFLAGS " in
    *" -g "* | *" -g3 "*) ;;
    *) CFLAGS_FOR_TARGET="-g $CFLAGS" ;;
  esac
fi
AC_SUBST(CFLAGS_FOR_TARGET)
...
(likewise CXXFLAGS_FOR_TARGET)

but substituting CFLAGS here is certainly wrong.  The above seems to be
overeagerly trying to honor CFLAGS more broadly as a convenience.  But
doing so when build != target looks wrong.

As alternative it should be documented that CFLAGS also applies to
target libraries unless CFLAGS_FOR_TARGET is set.