[Bug fortran/36495] New: libgfortran should be build with FCFLAGS -fimplicit-none

[burnus at gcc dot gnu dot org]

As PR 36471 shows, building libgfortran's Fortran parts with -fimplicit-none
can help detecting programming errors in the Fortran written parts of
libgfortran.

I suggest to use such a patch:

Index: configure.ac
===================================================================
--- configure.ac        (Revision 136654)
+++ configure.ac        (Arbeitskopie)
@@ -123,7 +123,7 @@ m4_rename([real_PRECIOUS],[_AC_ARG_VAR_P

 # Add -Wall -fno-repack-arrays -fno-underscoring if we are using GCC.
 if test "x$GCC" = "xyes"; then
-  AM_FCFLAGS="-I . -Wall -fno-repack-arrays -fno-underscoring"
+  AM_FCFLAGS="-I . -Wall -Werror -fimplicit-none -fno-repack-arrays
-fno-underscoring"
   ## We like to use C99 routines when available.  This makes sure that
   ## __STDC_VERSION__ is set such that libc includes make them available.
   AM_CFLAGS="-std=gnu99 -Wall -Wstrict-prototypes -Wmissing-prototypes
-Wold-style-definition -Wextra -Wwrite-strings"
Index: intrinsics/dprod_r8.f90
===================================================================
--- intrinsics/dprod_r8.f90     (Revision 136654)
+++ intrinsics/dprod_r8.f90     (Arbeitskopie)
@@ -20,6 +20,7 @@


 elemental function _gfortran_specific__dprod_r8 (p1, p2)
+   implicit none
    real (kind=4), intent (in) :: p1, p2
    real (kind=8) :: _gfortran_specific__dprod_r8


-- 
           Summary: libgfortran should be build with FCFLAGS -fimplicit-none
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: burnus at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36495