gdb/fortran: add support for RANK keyword

gfortran supports the RANK keyword, see:

  https://gcc.gnu.org/onlinedocs/gfortran/RANK.html#RANK

this commit adds support for this keyword to GDB's Fortran expression
parser.

gdb/ChangeLog:

	* f-exp.h (eval_op_f_rank): Declare.
	(expr::fortran_rank_operation): New typedef.
	* f-exp.y (exp): Handle UNOP_FORTRAN_RANK after parsing an
	UNOP_INTRINSIC.
	(f77_keywords): Add "rank" keyword.
	* f-lang.c (eval_op_f_rank): New function.
	* std-operator.def (UNOP_FORTRAN_RANK): New operator.

gdb/testsuite/ChangeLog:

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

1 files changed, 13 insertions, 0 deletions

diff --git a/gdb/f-exp.h b/gdb/f-exp.h
index 81cf341..f23c426 100644
--- a/gdb/f-exp.h
+++ b/gdb/f-exp.h
@@ -74,6 +74,17 @@ extern struct value * eval_op_f_allocated (struct type *expect_type,
 					   enum exp_opcode op,
 					   struct value *arg1);
 
+/* Implement the evaluation of UNOP_FORTRAN_RANK.  EXPECTED_TYPE, EXP, and
+   NOSIDE are as for expression::evaluate (see expression.h).  OP will
+   always be UNOP_FORTRAN_RANK, and ARG1 is the argument being passed to
+   the expression.   */
+
+extern struct value *eval_op_f_rank (struct type *expect_type,
+				     struct expression *exp,
+				     enum noside noside,
+				     enum exp_opcode op,
+				     struct value *arg1);
+
 namespace expr
 {
 
@@ -94,6 +105,8 @@ using fortran_associated_1arg = unop_operation<FORTRAN_ASSOCIATED,
 					       eval_op_f_associated>;
 using fortran_associated_2arg = binop_operation<FORTRAN_ASSOCIATED,
 						eval_op_f_associated>;
+using fortran_rank_operation = unop_operation<UNOP_FORTRAN_RANK,
+					      eval_op_f_rank>;
 
 /* The Fortran "complex" operation.  */
 class fortran_cmplx_operation