[Bug fortran/58904] ICE: accessing a component field of an unavailable type results in a seg fault

["janus at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58904

--- Comment #3 from janus at gcc dot gnu.org ---
Draft patch:


Index: gcc/fortran/decl.c
===================================================================
--- gcc/fortran/decl.c  (revision 242960)
+++ gcc/fortran/decl.c  (working copy)
@@ -5962,6 +5962,19 @@ gfc_match_function_decl (void)
       return m;
     }

+  if (current_ts.type == BT_DERIVED || current_ts.type == BT_CLASS)
+    {
+      sym = gfc_use_derived (current_ts.u.derived);
+
+      if (sym == NULL)
+       {
+         m = MATCH_ERROR;
+         goto cleanup;
+       }
+
+      current_ts.u.derived = sym;
+    }
+
   if (gfc_match ("function% %n", name) != MATCH_YES)
     {
       gfc_current_locus = old_loc;


This generates the right error, thus removing the ICE, but also produces
several follow-up errors, because the function statement is rejected:


c0.f90:3:14:

   TYPE(mytype) FUNCTION create_sort_range(b) result(r)
              1
Error: Derived type ‘mytype’ at (1) is being used before it is defined
c0.f90:4:13:

     INTEGER b
             1
Error: Unexpected data declaration statement in CONTAINS section at (1)
c0.f90:5:6:

     r%b = b
      1
Error: Symbol ‘r’ at (1) has no IMPLICIT type
c0.f90:6:5:

   END FUNCTION create_sort_range
     1
Error: Expecting END MODULE statement at (1)