[configure.ac] Updated comment about default options in CFLAGS for GCC.

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@13423 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 7 insertions, 2 deletions

diff --git a/configure.ac b/configure.ac
index 2fdb7626b..951d00ac6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -477,8 +477,13 @@ error
  CFLAGS="-fp_port -mieee-fp -wd1572 -wd265 -wd186 -wd239 $CFLAGS"
 ],[AC_MSG_RESULT(no)])
 
-dnl If compiler is gcc, then use some specific flags.
-dnl But don't touch user other flags.
+dnl If CFLAGS has not been set explicitly and the compiler is GCC, then
+dnl use some specific flags. But don't touch user other flags.
+dnl Note: This is done even when CFLAGS has been set from GMP's CFLAGS
+dnl (__GMP_CFLAGS macro in gmp.h) above. The consequence is that this
+dnl might yield a compilation failure if the -Werror option appears in
+dnl __GMP_CFLAGS. But in this case, since -Werror is not used by default,
+dnl one may expect that the user would also set CFLAGS for MPFR.
 if test "$test_CFLAGS" != set && test -n "$GCC"; then
   CFLAGS="-Wpointer-arith $CFLAGS"
   AC_MSG_CHECKING(whether the selected language is C++)