Fix and improve GUD Tooltip mode.

 lisp/tooltip.el (tooltip-identifier-from-point): Don't treat tokens
 inside comments and strings as identifiers.
 lisp/progmodes/gud.el (gud-tooltip-print-command): Quote the
 expression to evaluate.  This allows to evaluate expressions with
 embedded whitespace.
 (gud-tooltip-tips): Add a blank before the newline in the
 message-box text, for the benefit of message-box emulation on
 MS-Windows.
 lisp/progmodes/gdb-mi.el (gdb-tooltip-print): Don't ignore error
 messages from GDB, pop them up in a tooltip to give feedback to
 user.
 (gdb-tooltip-print-1): Quote the expression to evaluate.  This
 allows to evaluate expressions with embedded whitespace.
 (gdb-inferior-io--init-proc): Don't send "-inferior-tty" command
 if the TTY name is nil or empty (which happens when communicating
 with the inferior via pipes, e.g. on MS-Windows).
 (gdb-internals): If GDB sends a "&\n" empty debugging message,
 don't send that to the GUD buffer.

 doc/emacs/building.texi (Debugger Operation): Correct and improve
 documentation of the GUD Tooltip mode.

1 files changed, 7 insertions, 2 deletions

diff --git a/lisp/tooltip.el b/lisp/tooltip.el
index 9d0fbaae9d8..a57054acdd6 100644
--- a/lisp/tooltip.el
+++ b/lisp/tooltip.el
@@ -25,6 +25,8 @@
 
 ;;; Code:
 
+(require 'syntax)
+
 (defvar comint-prompt-regexp)
 
 (defgroup tooltip nil
@@ -277,8 +279,11 @@ Value is nil if no identifier exists at point.  Identifier extraction
 is based on the current syntax table."
   (save-excursion
     (goto-char point)
-    (let ((start (progn (skip-syntax-backward "w_") (point))))
-      (unless (looking-at "[0-9]")
+    (let* ((start (progn (skip-syntax-backward "w_") (point)))
+	   (pstate (syntax-ppss)))
+      (unless (or (looking-at "[0-9]")
+		  (nth 3 pstate)
+		  (nth 4 pstate))
 	(skip-syntax-forward "w_")
 	(when (> (point) start)
 	  (buffer-substring start (point)))))))