[Bug fortran/50525] gfortran should not allow early reference to entry dummy argument (r178939)

["burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50525

--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-09-27 14:27:39 UTC ---
The patch causes regressions as it comes before the check in resolve_variable
(search for "before the ENTRY", which covers a similar issue (cf PR 25090).
Namely:
  gfortran.dg/entry_dummy_ref_1.f90
  gfortran.dg/entry_dummy_ref_2.f90

False positive - ("n" used in a specification expression):
  gfortran.dg/entry_array_specs_2.f

 * * *

From the F2008 standard ("12.6.2.6 ENTRY statement", para 7):
  "In a subprogram, a name that appears as a dummy argument in an ENTRY 
   statement shall not appear in an executable statement preceding that ENTRY 
   statement, unless it also appears in a FUNCTION, SUBROUTINE, or ENTRY 
   statement that precedes the executable statement."

 * * *

Regarding resolve_variable: As cs_base == NULL, the existing check

5086      /* Deal with forward references to entries during resolve_code, to
5087         satisfy, at least partially, 12.5.2.5.  */
5088      if (gfc_current_ns->entries
5089          && current_entry_id == sym->entry_id
5090          && cs_base

fails and, hence, there is no error.

 * * *

Side remarks:

a) "before the ENTRY statement in which it is a parameter"
-> Misuse of the term "parameter"

b) "warning: ‘master.0.sub’ defined but not used"
-> Declare as DECL_ARTIFICIAL to avoid warning - or to handle it better if the
warning itself makes sense.