gdb/guile: improve the errors when creating breakpoints

When creating a breakpoint using the guile API, if an invalid
breakpoint type number was used then the error would report the wrong
argument position, like this:

  (gdb) guile (define wp2 (make-breakpoint "result" #:wp-class WP_WRITE #:type 999))
  ERROR: In procedure make-breakpoint:
  ERROR: In procedure gdbscm_make_breakpoint: Out of range: invalid breakpoint type in position 3: 999
  Error while executing Scheme code.
  (gdb)

The 'position 3' here is actually pointing at WP_WRITE, when it should
say 'position 5' and point to the 999.  This commit fixes this.

However, you also get errors like this:

  (gdb) guile (define wp2 (make-breakpoint "result" #:wp-class WP_WRITE #:type BP_NONE))
  ERROR: In procedure make-breakpoint:
  ERROR: In procedure gdbscm_make_breakpoint: Out of range: invalid breakpoint type in position 3: 0
  Error while executing Scheme code.

The BP_NONE is a valid breakpoint type, it's just not valid for
creating breakpoints through the 'make-breakpoint' API.  The use of
'0' in the error message (which is the value of BP_NONE) is not
great.  This commit changes the error in this case to:

  (gdb) guile (define wp2 (make-breakpoint "result" #:wp-class WP_WRITE #:type BP_NONE))
  ERROR: In procedure make-breakpoint:
  ERROR: In procedure gdbscm_make_breakpoint: unsupported breakpoint type in position 5: "BP_NONE"
  Error while executing Scheme code.

Which seems better; we now use the name of the type, and report that
this type is unsupported.

gdb/ChangeLog:

	* guile/scm-breakpoint.c (gdbscm_make_breakpoint): Split the error
	for invalid breakpoint numbers, and unsupported breakpoint
	numbers.

gdb/testsuite/ChangeLog:

	* gdb.guile/scm-breakpoint.exp (test_watchpoints): Add new tests.

1 files changed, 12 insertions, 1 deletions

diff --git a/gdb/guile/scm-breakpoint.c b/gdb/guile/scm-breakpoint.c
index 4ff197e..346b006 100644
--- a/gdb/guile/scm-breakpoint.c
+++ b/gdb/guile/scm-breakpoint.c
@@ -387,8 +387,19 @@ gdbscm_make_breakpoint (SCM location_scm, SCM rest)
 				     _("invalid watchpoint class"));
 	}
       break;
+    case bp_none:
+    case bp_hardware_watchpoint:
+    case bp_read_watchpoint:
+    case bp_access_watchpoint:
+      {
+	const char *type_name = bpscm_type_to_string (type);
+	gdbscm_misc_error (FUNC_NAME, type_arg_pos,
+			   gdbscm_scm_from_c_string (type_name),
+			   _("unsupported breakpoint type"));
+      }
+      break;
     default:
-      gdbscm_out_of_range_error (FUNC_NAME, access_type_arg_pos,
+      gdbscm_out_of_range_error (FUNC_NAME, type_arg_pos,
 				 scm_from_int (type),
 				 _("invalid breakpoint type"));
     }