gdb/fortran: add support for ASSOCIATED builtin

This commit adds support for the ASSOCIATED builtin to the Fortran
expression evaluator.  The ASSOCIATED builtin takes one or two
arguments.

When passed a single pointer argument GDB returns a boolean indicating
if the pointer is associated with anything.

When passed two arguments the second argument should either be some a
pointer could point at or a second pointer.

If the second argument is a pointer target, then the result from
associated indicates if the pointer is pointing at this target.

If the second argument is another pointer, then the result from
associated indicates if the two pointers are pointing at the same
thing.

gdb/ChangeLog:

	* f-exp.y (f77_keywords): Add 'associated'.
	* f-lang.c (fortran_associated): New function.
	(evaluate_subexp_f): Handle FORTRAN_ASSOCIATED.
	(operator_length_f): Likewise.
	(print_unop_or_binop_subexp_f): New function.
	(print_subexp_f): Make use of print_unop_or_binop_subexp_f for
	FORTRAN_ASSOCIATED, FORTRAN_LBOUND, and FORTRAN_UBOUND.
	(dump_subexp_body_f): Handle FORTRAN_ASSOCIATED.
	(operator_check_f): Likewise.
	* std-operator.def: Add FORTRAN_ASSOCIATED.

gdb/testsuite/ChangeLog:

	* gdb.fortran/associated.exp: New file.
	* gdb.fortran/associated.f90: New file.

1 files changed, 97 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.fortran/associated.f90 b/gdb/testsuite/gdb.fortran/associated.f90
new file mode 100644
index 0000000..093af53
--- /dev/null
+++ b/gdb/testsuite/gdb.fortran/associated.f90
@@ -0,0 +1,97 @@
+! Copyright 2021 Free Software Foundation, Inc.
+!
+! This program is free software; you can redistribute it and/or modify
+! it under the terms of the GNU General Public License as published by
+! the Free Software Foundation; either version 3 of the License, or
+! (at your option) any later version.
+!
+! This program is distributed in the hope that it will be useful,
+! but WITHOUT ANY WARRANTY; without even the implied warranty of
+! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+! GNU General Public License for more details.
+!
+! You should have received a copy of the GNU General Public License
+! along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+!
+! Start of test program.
+!
+program test
+
+  ! Things to point at.
+  integer, target :: array_1d (1:10) = 0
+  integer, target :: array_2d (1:10, 1:10) = 0
+  integer, target :: an_integer = 0
+  integer, target :: other_integer = 0
+  real, target :: a_real = 0.0
+
+  ! Things to point with.
+  integer, pointer :: array_1d_p (:) => null ()
+  integer, pointer :: other_1d_p (:) => null ()
+  integer, pointer :: array_2d_p (:,:) => null ()
+  integer, pointer :: an_integer_p => null ()
+  integer, pointer :: other_integer_p => null ()
+  real, pointer :: a_real_p => null ()
+
+  ! The start of the tests.
+  call test_associated (associated (array_1d_p))
+  call test_associated (associated (array_1d_p, array_1d))
+
+  array_1d_p => array_1d
+  call test_associated (associated (array_1d_p, array_1d))
+
+  array_1d_p => array_1d (2:10)
+  call test_associated (associated (array_1d_p, array_1d))
+
+  array_1d_p => array_1d (1:9)
+  call test_associated (associated (array_1d_p, array_1d))
+
+  array_1d_p => array_2d (3, :)
+  call test_associated (associated (array_1d_p, array_1d))
+  call test_associated (associated (array_1d_p, array_2d (2, :)))
+  call test_associated (associated (array_1d_p, array_2d (3, :)))
+
+  array_1d_p => null ()
+  call test_associated (associated (array_1d_p))
+  call test_associated (associated (array_1d_p, array_2d (3, :)))
+
+  call test_associated (associated (an_integer_p))
+  call test_associated (associated (an_integer_p, an_integer))
+  an_integer_p => an_integer
+  call test_associated (associated (an_integer_p))
+  call test_associated (associated (an_integer_p, an_integer))
+
+  call test_associated (associated (an_integer_p, other_integer_p))
+  other_integer_p => other_integer
+  call test_associated (associated (other_integer_p))
+  call test_associated (associated (an_integer_p, other_integer_p))
+  call test_associated (associated (other_integer_p, an_integer_p))
+  call test_associated (associated (other_integer_p, an_integer))
+
+  other_integer_p = an_integer_p
+  call test_associated (associated (an_integer_p, other_integer_p))
+  call test_associated (associated (other_integer_p, an_integer_p))
+
+  call test_associated (associated (a_real_p))
+  call test_associated (associated (a_real_p, a_real))
+  a_real_p => a_real
+  call test_associated (associated (a_real_p, a_real))
+
+  ! Setup for final tests, these are performed at the print line
+  ! below.  These final tests are all error conditon checks,
+  ! i.e. things that can't be compiled into Fortran.
+  array_1d_p => array_1d
+
+  print *, "" ! Final Breakpoint
+  print *, an_integer
+  print *, a_real
+
+contains
+
+  subroutine test_associated (answer)
+    logical :: answer
+
+    print *,answer	! Test Breakpoint
+  end subroutine test_associated
+
+end program test