Fortran - ICE in gfc_check_do_variable, at fortran/parse.c:4446

Avoid NULL pointer dereferences during error recovery.

gcc/fortran/ChangeLog:

	PR fortran/95501
	PR fortran/95502
	* expr.c (gfc_check_pointer_assign): Avoid NULL pointer
	dereference.
	* match.c (gfc_match_pointer_assignment): Likewise.
	* parse.c (gfc_check_do_variable): Avoid comparison with NULL
	symtree.

gcc/testsuite/ChangeLog:

	PR fortran/95501
	PR fortran/95502
	* gfortran.dg/pr95502.f90: New test.

gcc/fortran/expr.c

@@ -1683,10 +1683,21 @@ find_array_section (gfc_expr *expr, gfc_ref *ref)
 	  return false;
 	}
 
+#if 1
       cons = gfc_constructor_lookup (base, limit);
       gcc_assert (cons);
       gfc_constructor_append_expr (&expr->value.constructor,
 				   gfc_copy_expr (cons->expr), NULL);
+#else
+      cons = gfc_constructor_lookup (base, limit);
+      if (cons)
+	gfc_constructor_append_expr (&expr->value.constructor,
+				     gfc_copy_expr (cons->expr), NULL);
+      else
+	{
+	  t = false;
+	}
+#endif
     }
 
   mpz_clear (ptr);
@@ -3476,6 +3487,7 @@ gfc_specification_expr (gfc_expr *e)
     {
       gfc_error ("Expression at %L must be of INTEGER type, found %s",
 		 &e->where, gfc_basic_typename (e->ts.type));
+      gfc_clear_ts (&e->ts);
       return false;
     }
 
@@ -3815,6 +3827,9 @@ gfc_check_pointer_assign (gfc_expr *lvalue, gfc_expr *rvalue,
   int proc_pointer;
   bool same_rank;
 
+  if (!lvalue->symtree)
+    return false;
+
   lhs_attr = gfc_expr_attr (lvalue);
   if (lvalue->ts.type == BT_UNKNOWN && !lhs_attr.proc_pointer)
     {

gcc/fortran/match.c

@@ -1409,7 +1409,7 @@ gfc_match_pointer_assignment (void)
   gfc_matching_procptr_assignment = 0;
 
   m = gfc_match (" %v =>", &lvalue);
-  if (m != MATCH_YES)
+  if (m != MATCH_YES || !lvalue->symtree)
     {
       m = MATCH_NO;
       goto cleanup;

gcc/fortran/parse.c

@@ -4588,6 +4588,9 @@ gfc_check_do_variable (gfc_symtree *st)
 {
   gfc_state_data *s;
 
+  if (!st)
+    return 0;
+
   for (s=gfc_state_stack; s; s = s->previous)
     if (s->do_variable == st)
       {

gcc/testsuite/gfortran.dg/pr95502.f90

@@ -0,0 +1,8 @@
+! { dg-do compile }
+! PR fortran/95502 - ICE in gfc_check_do_variable, at fortran/parse.c:4446
+
+program p
+  integer, pointer :: z
+  nullify (z%kind)  ! { dg-error "in variable definition context" }
+  z%kind => NULL()  ! { dg-error "constant expression" }
+end