keep FCFLAGS during gfortran configure

build/bin/sage-build-env-config.in

@@ -32,10 +32,10 @@ if [ "x$SAGE_DEBUG" == "x" ]; then
 fi
 
 # The configured compilation flags.
-export CONFIGURED_CFLAGS="@CONFIGURED_CFLAGS@"
-export CONFIGURED_CXXFLAGS="@CONFIGURED_CXXFLAGS@"
-export CONFIGURED_FCFLAGS="@CONFIGURED_FCFLAGS@"
-export CONFIGURED_F77FLAGS="@CONFIGURED_F77FLAGS@"
+export CONFIGURED_CFLAGS="@CFLAGS@"
+export CONFIGURED_CXXFLAGS="@CXXFLAGS@"
+export CONFIGURED_FCFLAGS="@FCFLAGS@"
+export CONFIGURED_F77FLAGS="@F77FLAGS@"
 
 # This is usually blank if the system GMP is used, or $SAGE_LOCAL otherwise
 export SAGE_GMP_PREFIX="@SAGE_GMP_PREFIX@"

build/pkgs/gfortran/spkg-configure.m4

@@ -31,6 +31,16 @@ AC_DEFUN([SAGE_MUST_INSTALL_GFORTRAN], [
     fi
 ])
 
+dnl This macro saves current FCFLAGS for later use.
+AC_DEFUN([SAGE_SAVE_FCFLAGS], [
+    sage_saved_fcflags=$FCFLAGS
+])
+
+dnl This macro restores saved FCFLAGS.
+AC_DEFUN([SAGE_RESTORE_FCFLAGS], [
+    FCFLAGS=$sage_saved_fcflags
+])
+
 
 SAGE_SPKG_CONFIGURE([gfortran], [
     AC_REQUIRE([SAGE_SPKG_CONFIGURE_GCC])
@@ -40,12 +50,19 @@ SAGE_SPKG_CONFIGURE([gfortran], [
     # This helps verify the compiler works too, so if some idiot sets FC to
     # /usr/bin/ls, we will at least know it's not a working Fortran
     # compiler.
+    AC_REQUIRE([SAGE_SAVE_FCFLAGS])
     AC_FC_FREEFORM([SAGE_HAVE_FC_FREEFORM=yes], [
 	AC_MSG_NOTICE([Your Fortran compiler does not accept free-format source code])
         AC_MSG_NOTICE([which means the compiler is either seriously broken, or])
         AC_MSG_NOTICE([is too old to build Sage.])
         SAGE_HAVE_FC_FREEFORM=no])
 
+    # AC_FC_FREEFORM may have added flags.
+    # However, it is up to the individual package how they invoke the
+    # Fortran compiler.
+    # We only check here, whether the compiler is suitable.
+    AC_REQUIRE([SAGE_RESTORE_FCFLAGS])
+
     AS_VAR_IF(SAGE_HAVE_FC_FREEFORM, [no], [
         AS_VAR_SET(sage_spkg_install_gfortran, [yes])
     ])

configure.ac

@@ -313,10 +313,10 @@ AX_PROG_PERL_VERSION([5.8.0],[],[
 ###############################################################################
 
 # Save compiler flags as configured by the user.
-AC_SUBST(CONFIGURED_CFLAGS, "$CFLAGS")
-AC_SUBST(CONFIGURED_CXXFLAGS, "$CXXFLAGS")
-AC_SUBST(CONFIGURED_FCFLAGS, "$FCFLAGS")
-AC_SUBST(CONFIGURED_F77FLAGS, "$F77FLAGS")
+AC_SUBST(CFLAGS, "$CFLAGS")
+AC_SUBST(CXXFLAGS, "$CXXFLAGS")
+AC_SUBST(FCFLAGS, "$FCFLAGS")
+AC_SUBST(F77FLAGS, "$F77FLAGS")
 
 SAGE_CHECK_CONDA_COMPILERS