The attached patch fixes an accepts-invalid while enforcing

  C1560 (R1530) If RESULT appears, the function-name shall not appear
  in any specification statement in the scoping unit of the function
  subprogram.

Regression tested on x86_64-*-freebsd.  OK to commit?

2018-03-19  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/42651
	* decl.c (check_function_name): Improved error message
	(gfc_match_volatile, gfc_match_asynchronous) Use check_function_name.

2018-03-19  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/42651
	* gfortran.dg/pr42651.f90: New test.
	* gfortran.df/func_result_7.f90: Update for new error message.
-- 
Steve