Fix PR 94270 by not warning about artifical dummy arguments.

2020-04-14  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/94270
	* interface.c (gfc_get_formal_from_actual_arglist): Always
	set artificial attribute for symbols.
	* trans-decl.c (generate_local_decl): Do not warn if the
	symbol is artifical.

2020-04-14  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/94270
	* gfortran.dg/warn_unused_dummy_argument_6.f90: New test.

gcc/fortran/interface.c

@@ -5317,7 +5317,6 @@ gfc_get_formal_from_actual_arglist (gfc_symbol *sym,
 	      s->ts.is_iso_c = 0;
 	      s->ts.is_c_interop = 0;
 	      s->attr.flavor = FL_VARIABLE;
-	      s->attr.artificial = 1;
 	      if (a->expr->rank > 0)
 		{
 		  s->attr.dimension = 1;
@@ -5332,6 +5331,7 @@ gfc_get_formal_from_actual_arglist (gfc_symbol *sym,
 		s->maybe_array = maybe_dummy_array_arg (a->expr);
 	    }
 	  s->attr.dummy = 1;
+	  s->attr.artificial = 1;
 	  s->declared_at = a->expr->where;
 	  s->attr.intent = INTENT_UNKNOWN;
 	  (*f)->sym = s;

gcc/fortran/trans-decl.c

@@ -6072,7 +6072,7 @@ generate_local_decl (gfc_symbol * sym)
       /* Unused procedure passed as dummy argument.  */
       if (sym->attr.flavor == FL_PROCEDURE)
 	{
-	  if (!sym->attr.referenced)
+	  if (!sym->attr.referenced && !sym->attr.artificial)
 	    {
 	      if (warn_unused_dummy_argument)
 		gfc_warning (OPT_Wunused_dummy_argument,

gcc/testsuite/gfortran.dg/warn_unused_dummy_argument_6.f90

+! { dg-do compile }
+! { dg-options "-Wall" }
+! PR 94270 - this used to give a bogus warning.
+! Test case by Ignacio Fernández Galván.
+subroutine foo()
+external bar
+call meh(bar)
+call foo_internal()
+contains
+  subroutine foo_internal()
+    call meh(bar)
+  end subroutine foo_internal
+end subroutine foo