Enable %LOC as an rvalue with -std=legacy.

	gcc/fortran/
        * primary.c (gfc_match_rvalue): Match %LOC as LOC with -std=legacy.
        * gfortran.texi: Document.

	gcc/testsuite/gfortran.dg/
	* dec_loc_rval_1.f90: New test.
        * dec_loc_rval_2.f90: New test.
        * dec_loc_rval_3.f90: New test.

From-SVN: r241519

gcc/fortran/ChangeLog

 2016-10-25  Fritz Reese <fritzoreese@gmail.com>
 
+        * primary.c (gfc_match_rvalue): Match %LOC as LOC with -std=legacy.
+        * gfortran.texi: Document.
+
+2016-10-25  Fritz Reese <fritzoreese@gmail.com>
+
 	* decl.c (gfc_match_type): New function.
 	* match.h (gfc_match_type): New function.
 	* match.c (gfc_match_if): Special case for one-line IFs.

gcc/fortran/gfortran.texi

@@ -1467,6 +1467,7 @@ compatibility extensions along with those enabled by @option{-std=legacy}.
 * Extended math intrinsics::
 * Form feed as whitespace::
 * TYPE as an alias for PRINT::
+* %LOC as an rvalue::
 @end menu
 
 @node Old-style kind specifications
@@ -2537,6 +2538,26 @@ TYPE *, 'hello world'
 PRINT *, 'hello world'
 @end smallexample
 
+@node %LOC as an rvalue
+@subsection %LOC as an rvalue
+@cindex LOC
+Normally @code{%LOC} is allowed only in parameter lists.  However the intrinsic
+function @code{LOC} does the same thing, and is usable as the right-hand-side of
+assignments. For compatibility, GNU Fortran supports the use of @code{%LOC} as
+an alias for the builtin @code{LOC} with @option{-std=legacy}.  With this
+feature enabled the following two examples are equivalent:
+
+@smallexample
+integer :: i, l
+l = %loc(i)
+call sub(l)
+@end smallexample
+
+@smallexample
+integer :: i
+call sub(%loc(i))
+@end smallexample
+
 
 @node Extensions not implemented in GNU Fortran
 @section Extensions not implemented in GNU Fortran

gcc/fortran/primary.c

@@ -2971,9 +2971,20 @@ gfc_match_rvalue (gfc_expr **result)
   bool implicit_char;
   gfc_ref *ref;
 
-  m = gfc_match_name (name);
-  if (m != MATCH_YES)
-    return m;
+  m = gfc_match ("%%loc");
+  if (m == MATCH_YES)
+    {
+      if (!gfc_notify_std (GFC_STD_LEGACY, "%%LOC() as an rvalue at %C"))
+        return MATCH_ERROR;
+      strncpy (name, "loc", 4);
+    }
+
+  else
+    {
+      m = gfc_match_name (name);
+      if (m != MATCH_YES)
+        return m;
+    }
 
   /* Check if the symbol exists.  */
   if (gfc_find_sym_tree (name, NULL, 1, &symtree))

gcc/testsuite/ChangeLog

 2016-10-25  Fritz Reese <fritzoreese@gmail.com>
 
+	* gfortran.dg/dec_loc_rval_1.f90: New test.
+	* gfortran.dg/dec_loc_rval_2.f90: New test.
+	* gfortran.dg/dec_loc_rval_3.f90: New test.
+
+2016-10-25  Fritz Reese <fritzoreese@gmail.com>
+
 	* gfortran.dg/dec_type_print.f90: New testcase.
 
 2016-10-25  Fritz Reese <fritzoreese@gmail.com>

gcc/testsuite/gfortran.dg/dec_loc_rval_1.f90

+! { dg-do run }
+! { dg-options "-std=legacy" }
+!
+! Test the usage of %loc as an rvalue.
+!
+program main
+implicit none
+
+integer :: i, j, k
+
+i =  loc(j)
+k = %loc(j)
+
+if (i .ne. k) then
+  print *, "bad %loc value"
+  call abort()
+endif
+
+end

gcc/testsuite/gfortran.dg/dec_loc_rval_2.f90

+! { dg-do compile }
+! { dg-options "-std=gnu" }
+!
+! Test warnings for usage of %loc as an rvalue without -std=legacy.
+!
+program main
+implicit none
+
+integer, volatile :: i, j, k
+
+i =  loc(j)
+k = %loc(j) ! { dg-warning "Legacy Extension:" }
+
+end

gcc/testsuite/gfortran.dg/dec_loc_rval_3.f03

+! { dg-do compile }
+! { dg-options "-std=f2003" }
+!
+! Test errors for usage of %loc as an rvalue with a real standard.
+!
+program main
+implicit none
+
+integer, volatile :: i, j, k
+
+k = %loc(j) ! { dg-error "Legacy Extension:" }
+
+end