gdb: Convert enum range_type to a bit field enum

The expression range_type enum represents the following ideas:

  - Lower bound is set to default,
  - Upper bound is set to default,
  - Upper bound is exclusive.

There are currently 6 entries in the enum to represent the combination
of all those ideas.

In a future commit I'd like to add stride information to the range,
this could in theory appear with any of the existing enum entries, so
this would take us to 12 enum entries.

This feels like its getting a little out of hand, so in this commit I
switch the range_type enum over to being a flags style enum.  There's
one entry to represent no flags being set, then 3 flags to represent
the 3 ideas above.  Adding stride information will require adding only
one more enum flag.

I've then gone through and updated the code to handle this change.

There should be no user visible changes after this commit.

gdb/ChangeLog:

	* expprint.c (print_subexp_standard): Update to reflect changes to
	enum range_type.
	(dump_subexp_body_standard): Likewise.
	* expression.h (enum range_type): Convert to a bit field enum, and
	make the enum unsigned.
	* f-exp.y (subrange): Update to reflect changes to enum
	range_type.
	* f-lang.c (value_f90_subarray): Likewise.
	* parse.c (operator_length_standard): Likewise.
	* rust-exp.y (rust_parser::convert_ast_to_expression): Likewise.
	* rust-lang.c (rust_range): Likewise.
	(rust_compute_range): Likewise.
	(rust_subscript): Likewise.

1 files changed, 7 insertions, 15 deletions

diff --git a/gdb/parse.c b/gdb/parse.c
index 6b9541bfdc2..6661fba81d7 100644
--- a/gdb/parse.c
+++ b/gdb/parse.c
@@ -921,21 +921,13 @@ operator_length_standard (const struct expression *expr, int endpos,
       range_type = (enum range_type)
 	longest_to_int (expr->elts[endpos - 2].longconst);
 
-      switch (range_type)
-	{
-	case LOW_BOUND_DEFAULT:
-	case LOW_BOUND_DEFAULT_EXCLUSIVE:
-	case HIGH_BOUND_DEFAULT:
-	  args = 1;
-	  break;
-	case BOTH_BOUND_DEFAULT:
-	  args = 0;
-	  break;
-	case NONE_BOUND_DEFAULT:
-	case NONE_BOUND_DEFAULT_EXCLUSIVE:
-	  args = 2;
-	  break;
-	}
+      /* Assume the range has 2 arguments (low bound and high bound), then
+	 reduce the argument count if any bounds are set to default.  */
+      args = 2;
+      if (range_type & RANGE_LOW_BOUND_DEFAULT)
+	--args;
+      if (range_type & RANGE_HIGH_BOUND_DEFAULT)
+	--args;
 
       break;