Fortran: fix error recovery on invalid array section

gcc/fortran/ChangeLog:

	PR fortran/105230
	* expr.c (find_array_section): Correct logic to avoid NULL
	pointer dereference on invalid array section.

gcc/testsuite/ChangeLog:

	PR fortran/105230
	* gfortran.dg/pr105230.f90: New test.

Co-authored-by: Steven G. Kargl <kargl@gcc.gnu.org>
(cherry picked from commit 0acdbe29f6)

gcc/fortran/expr.c

@@ -1553,8 +1553,8 @@ find_array_section (gfc_expr *expr, gfc_ref *ref)
 	  if ((begin && begin->expr_type != EXPR_CONSTANT)
 	      || (finish && finish->expr_type != EXPR_CONSTANT)
 	      || (step && step->expr_type != EXPR_CONSTANT)
-	      || (!begin && !lower)
-	      || (!finish && !upper))
+	      || !lower
+	      || !upper)
 	    {
 	      t = false;
 	      goto cleanup;

gcc/testsuite/gfortran.dg/pr105230.f90

@@ -0,0 +1,8 @@
+! { dg-do compile }
+! PR fortran/105230 - ICE in find_array_section
+! Contributed by G.Steinmetz
+
+program p
+  integer, parameter :: a(:) = [1, 2] ! { dg-error "deferred shape" }
+  print *, reshape([3, 4], a(1:2))
+end