Fortran] PR93309 – permit repeated 'implicit none(external)'

        PR fortran/93309
        * interface.c (gfc_procedure_use): Also check parent namespace for
        'implict none (external)'.
        * symbol.c (gfc_get_namespace): Don't set has_implicit_none_export
        to parent namespace's setting.

        PR fortran/93309
        * gfortran.dg/external_implicit_none_2.f90: New.

gcc/fortran/ChangeLog

+2020-01-21  Tobias Burnus  <tobias@codesourcery.com>
+
+	PR fortran/93309
+	* interface.c (gfc_procedure_use): Also check parent namespace for
+	'implict none (external)'.
+	* symbol.c (gfc_get_namespace): Don't set has_implicit_none_export
+	to parent namespace's setting. 
+
 2020-01-19  Thomas König  <tkoenig@gcc.gnu.org>
 
 	PR fortran/44960

gcc/fortran/interface.c

@@ -3798,8 +3798,16 @@ gfc_procedure_use (gfc_symbol *sym, gfc_actual_arglist **ap, locus *where)
      explicitly declared at all if requested.  */
   if (sym->attr.if_source == IFSRC_UNKNOWN && !sym->attr.is_iso_c)
     {
+      bool has_implicit_none_export = false;
       implicit = true;
-      if (sym->ns->has_implicit_none_export && sym->attr.proc == PROC_UNKNOWN)
+      if (sym->attr.proc == PROC_UNKNOWN)
+	for (gfc_namespace *ns = sym->ns; ns; ns = ns->parent)
+	  if (ns->has_implicit_none_export)
+	    {
+	      has_implicit_none_export = true;
+	      break;
+	    }
+      if (has_implicit_none_export)
 	{
 	  const char *guessed
 	    = gfc_lookup_function_fuzzy (sym->name, sym->ns->sym_root);

gcc/fortran/symbol.c

@@ -2898,9 +2898,6 @@ gfc_get_namespace (gfc_namespace *parent, int parent_types)
 	}
     }
 
-  if (parent_types && ns->parent != NULL)
-    ns->has_implicit_none_export = ns->parent->has_implicit_none_export;
-
   ns->refs = 1;
 
   return ns;

gcc/testsuite/ChangeLog

+2020-01-21  Tobias Burnus  <tobias@codesourcery.com>
+
+	PR fortran/93309
+	* gfortran.dg/external_implicit_none_2.f90: New.
+
 2020-01-21  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/92328

gcc/testsuite/gfortran.dg/external_implicit_none_2.f90

+! { dg-do compile }
+!
+! PR fortran/93309
+!
+module m
+  implicit none(external)
+contains
+  subroutine s
+    implicit none(external) ! OK
+  end subroutine
+end module
+
+module m2
+  implicit none(external)
+contains
+  subroutine s
+    call foo(1)  ! { dg-error "not explicitly declared" }
+  end subroutine
+end module
+
+module m3
+  implicit none(external)
+contains
+  subroutine s
+    implicit none(external) ! OK
+    implicit none(external) ! { dg-error "Duplicate IMPLICIT NONE statement" }
+  end subroutine
+end module