[Bug fortran/37513] New: Wrongly rejects: unprotected_pointer => protected_pointer

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

+++ This bug was initially created as a clone of Bug #37504 +++

gfortran rightly rejects the following program, however, the error message is
misleading:

  PROTECTED at (1) only allowed in specification part of a module

module m
  implicit none
  integer, pointer, protected :: protected_pointer
end module m

program p
  use m
  implicit none
  integer, pointer :: unprotected_pointer
  protected_pointer => unprotected_pointer
end program p

 * * *

The reason is as follows:

decode_statement calls "gfc_match_pointer_assignment" which calls in turn
match_variable, which calls "gfc_error ("Assigning to PROTECTED variable at
%C");". However, as "gfc_match_pointer_assignment" does not return MATCH_YES,
one proceeds in decode_statement and reaches gfc_match_protected, which also
calls gfc_error. Only the last error message is printed, i.e. the one of
gfc_match_protected.

 * * *

My first attempt was to do an
  if(gfc_match_pointer_assignment() == MATCH_ERROR) goto error;
however, that fails since gfc_match_pointer_assignment returns MATCH_NO and not
MATCH_ERROR if  match ("%v =>")  fails. (It fails because of the "Assigning to
PROTECTED variable at %C".)

Removing the "m = MATCH_NO" in gfc_match_pointer_assignment works for this test
case, but let's several test cases fail in the test suite. Note: The checks for
PROTECTED in gfc_match_assignment and gfc_match_pointer_assignment are not
needed as the match_variable() check comes first.

 * * *

My next attempt was to remove the current checks from primary.c and match.c and
insert them into gfc_check_assign / gfc_check_pointer_assign. However, that
fails for e.g. protected_5.f90: I miss an error for "allocate(t%array(15))" but
I get one for "use good2", which is not only the lexpr->where/rexpr->where, but
also the case if "use good2" is the only statement in "program main". I fail to
understand why this goes wrong.


-- 
           Summary: Wrongly rejects: unprotected_pointer =>
                    protected_pointer
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: burnus at gcc dot gnu dot org
 BugsThisDependsOn: 37504


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37513