Trac #26715: build/pkgs/gfortran/spkg-configure.m4 works incorrectly …

…if CC and CXX are already there

As a result of refactoring configure.ac in #24919,
absence of (g)fortran now forces installation of full gcc, instead of
just gfortran part of it.

This is particularly crucial on OSX, where we don't normally build full
gcc any more, but only build gfortran.

To reproduce, move gfortran out of your PATH, and re-run ./configure.
You'll see that now `gcc` and `gfortran` are scheduled for
installation...

URL: https://trac.sagemath.org/26715
Reported by: dimpase
Ticket author(s): François Bissey
Reviewer(s): Erik Bray

build/pkgs/gcc/spkg-configure.m4

@@ -54,7 +54,6 @@ SAGE_SPKG_CONFIGURE([gcc], [
 	AC_REQUIRE([AC_PROG_CC])
 	AC_REQUIRE([AC_PROG_CPP])
 	AC_REQUIRE([AC_PROG_CXX])
-	AC_REQUIRE([AC_PROG_FC])
 	AC_REQUIRE([AC_PROG_OBJC])
 	AC_REQUIRE([AC_PROG_OBJCXX])
 
@@ -149,7 +148,6 @@ SAGE_SPKG_CONFIGURE([gcc], [
             SAGE_SHOULD_INSTALL_GCC([$CC ($GCC_VERSION) and $CXX ($GXX_VERSION) are not the same version])
         fi
 
-        # assuming gfortran does work
     fi
 
     # Check that the assembler and linker used by $CXX match $AS and $LD.

build/pkgs/gfortran/spkg-configure.m4

@@ -1,33 +1,20 @@
 SAGE_SPKG_CONFIGURE([gfortran], [
-    AC_REQUIRE([AC_PROG_FC])
     AC_REQUIRE([SAGE_SPKG_CONFIGURE_GCC])
+    AC_REQUIRE([AC_PROG_FC])
+    # Check that the Fortran compiler accepts free-format source code (as
+    # opposed to the older fixed-format style from Fortran 77).
+    # 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_FC_FREEFORM([], [
+	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_spkg_install_gfortran=yes])
 
     # Special case: If we are already installing gcc then don't install
     # gfortran since it's included
     if test "x$sage_spkg_install_gcc" = "xyes" -o x$SAGE_INSTALL_GCC = xexists; then
         sage_spkg_install_gfortran=no
-    else
-        # Check that the Fortran compiler accepts free-format source code (as
-        # opposed to the older fixed-format style from Fortran 77).
-        # 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.
-        if test -z "$FC"; then
-            sage_spkg_install_gfortran=yes
-            SAGE_MUST_INSTALL_GCC([a Fortran compiler is missing])
-        fi
-
-        # see http://www.gnu.org/software/hello/manual/autoconf/Fortran-Compiler.html
-        AC_FC_FREEFORM([], [
-            AC_MSG_NOTICE([Your Fortran compiler does not accept free-format source code])
-            AC_MSG_NOTICE([which means the compiler is either seriously broken, or])
-            AC_MSG_NOTICE([is too old to build Sage.])
-            sage_spkg_install_gfortran=yes
-        ])
-
-        # Check compiler versions
-        if test x$GFC != xyes; then
-            sage_spkg_install_gfortran=yes
-        fi
     fi
 ])