[Bug fortran/59016] f951: internal compiler error: Segmentation fault

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59016

--- Comment #9 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
I have tested on trunk (5.0) the following variant

--- ../_clean/gcc/fortran/interface.c    2015-03-25 14:07:04.000000000 +0100
+++ gcc/fortran/interface.c    2015-03-30 10:05:08.000000000 +0200
@@ -1558,7 +1569,7 @@ next:
    something goes wrong.  */

 static int
-check_interface0 (gfc_interface *p, const char *interface_name)
+check_interface0 (gfc_interface *p, const char *interface_name, gfc_symbol
*origin)
 {
   gfc_interface *psave, *q, *qlast;

@@ -1571,7 +1582,16 @@ check_interface0 (gfc_interface *p, cons
        || !p->sym->attr.if_source)
       && p->sym->attr.flavor != FL_DERIVED)
     {
-      if (p->sym->attr.external)
+      if (origin)
+        {
+           /* since program crashes, print access statement info or just the
name; then exit! */
+           if (origin->declared_at.lb->file)
+          gfc_error ("undefined function/subroutine for %s at %L ",
+                interface_name, &origin->declared_at);
+           else
+         gfc_error ("undefined function/subroutine for %s ",interface_name);
+        }
+      else if (p->sym->attr.external)
         gfc_error ("Procedure %qs in %s at %L has no explicit interface",
                p->sym->name, interface_name, &p->sym->declared_at);
       else
@@ -1689,7 +1709,7 @@ check_sym_interfaces (gfc_symbol *sym)
   if (sym->generic != NULL)
     {
       sprintf (interface_name, "generic interface '%s'", sym->name);
-      if (check_interface0 (sym->generic, interface_name))
+      if (check_interface0 (sym->generic, interface_name, sym))
     return;

       for (p = sym->generic; p; p = p->next)
@@ -1721,7 +1741,7 @@ check_uop_interfaces (gfc_user_op *uop)
   gfc_namespace *ns;

   sprintf (interface_name, "operator interface '%s'", uop->name);
-  if (check_interface0 (uop->op, interface_name))
+  if (check_interface0 (uop->op, interface_name, NULL))
     return;

   for (ns = gfc_current_ns; ns; ns = ns->parent)
@@ -1814,7 +1834,7 @@ gfc_check_interfaces (gfc_namespace *ns)
     sprintf (interface_name, "intrinsic '%s' operator",
          gfc_op2string ((gfc_intrinsic_op) i));

-      if (check_interface0 (ns->op[i], interface_name))
+      if (check_interface0 (ns->op[i], interface_name, NULL))
     continue;

       if (ns->op[i])

It fixes this PR and at least pr56674, pr58813, pr59024, and pr65469. However
it causes the following regressions:

FAIL: gfortran.dg/constructor_9.f90   -O   (test for errors, line 13)
FAIL: gfortran.dg/constructor_9.f90   -O  (test for excess errors)
FAIL: gfortran.dg/generic_14.f90   -O   (test for errors, line 90)
FAIL: gfortran.dg/generic_14.f90   -O   (test for errors, line 99)
FAIL: gfortran.dg/generic_14.f90   -O  (test for excess errors)
FAIL: gfortran.dg/keyword_symbol_1.f90   -O   (test for errors, line 20)
FAIL: gfortran.dg/keyword_symbol_1.f90   -O  (test for excess errors)
FAIL: gfortran.dg/proc_decl_3.f90   -O   (test for errors, line 37)
FAIL: gfortran.dg/proc_decl_3.f90   -O   (test for errors, line 38)
FAIL: gfortran.dg/proc_decl_3.f90   -O   (test for errors, line 39)
FAIL: gfortran.dg/proc_decl_3.f90   -O  (test for excess errors)