fortran: Fix specification expression check in submodules [PR114475]

The patch fixing PR111781 made the check of specification expressions more
restrictive, disallowing local variables in specification expressions of
dummy arguments.  PR114475 showed an example where that change regressed,
disallowing in submodules expressions that had been allowed in the parent
module.  In submodules indeed, the hierarchy of namespaces inherited from
the parent module is not reproduced so the host-association of symbols
can't be recognized by checking the nesting of namespaces.

This change fixes the problem by allowing in specification expressions
all the symbols in a submodule that are inherited from the parent module.

	PR fortran/111781
	PR fortran/114475

gcc/fortran/ChangeLog:

	* expr.cc (check_restricted): In submodules, allow variables host-
	associated from the parent module.

gcc/testsuite/ChangeLog:

	* gfortran.dg/spec_expr_10.f90: New test.

Co-authored-by: Harald Anlauf <anlauf@gmx.de>

gcc/fortran/expr.cc

@@ -3517,6 +3517,7 @@ check_restricted (gfc_expr *e)
       if (e->error
 	    || sym->attr.in_common
 	    || sym->attr.use_assoc
+	    || sym->attr.used_in_submodule
 	    || sym->attr.dummy
 	    || sym->attr.implied_index
 	    || sym->attr.flavor == FL_PARAMETER

gcc/testsuite/gfortran.dg/spec_expr_10.f90

@@ -0,0 +1,46 @@
+! { dg-do compile }
+!
+! PR fortran/114475
+! The array specification of PP in OL_EVAL used to be rejected in the submodule
+! because the compiler was not able to see the host-association of N_EXTERNAL
+! there.
+!
+! Contributed by Jürgen Reuter <juergen.reuter@desy.de>.
+
+module t1
+  use, intrinsic :: iso_c_binding
+  implicit none
+  private
+  public :: t1_t
+  integer :: N_EXTERNAL = 0
+
+  type :: t1_t
+  contains
+    procedure :: set_n_external => t1_set_n_external
+  end type t1_t
+
+  abstract interface
+     subroutine ol_eval (id, pp, emitter) bind(C)
+       import
+       real(kind = c_double), intent(in) :: pp(5 * N_EXTERNAL)
+     end subroutine ol_eval
+  end interface
+  interface
+    module subroutine t1_set_n_external (object, n)
+      class(t1_t), intent(inout) :: object
+      integer, intent(in) :: n
+    end subroutine t1_set_n_external
+  end interface
+
+end module t1
+
+submodule (t1) t1_s
+  implicit none
+contains
+  module subroutine t1_set_n_external (object, n)
+    class(t1_t), intent(inout) :: object
+    integer, intent(in) :: n
+    N_EXTERNAL = n
+  end subroutine t1_set_n_external
+
+end submodule t1_s