master 07e1852: Enhance memory address evaluation in gdb-mi

[Eli Zaretskii]

branch: master
commit 07e1852c9b58ffa86443f61705e3dae4af0736f7
Author: Yuan Fu <address@hidden>
Commit: Eli Zaretskii <address@hidden>

    Enhance memory address evaluation in gdb-mi
    
    Before, the memory buffer evaluated the expression as address and used
    the fixed result in each stop.  This change store the expression
    itself and reevaluates it in each stop to yield an address.
    We also add a warning (a red bold exclamation mark) on the header line
    when the content of the page doesn't represent the memory location
    user requested for.  That happends when some error occurs in
    evaluating the address, and we display the last successfully displayed
    memory page.
    * lisp/progmodes/gdb-mi.el (gdb-memory-address-expression)
    (gdb--memory-display-warning): New variables.
    (gdb-memory-address): Change default value to nil; add docstring.
    (def-gdb-trigger-and-handler, gdb-invalidate-memory)
    (gdb-memory-set-address): Replace 'gdb-memory-address' with
    'gdb-memory-address-expression'.
    (gdb-memory-header): Add code to display
    'gdb-memory-address-expression' on header line.  Move the mouse event
    from address to expression.  Add code to display the warning.
    (gdb-memory-header): Fix the error from
    'propertize' when 'gdb-memory-address-expression' or
    'gdb-memory-address' is nil.
    (gdb-read-memory-custom): Change 'error' to 'user-error'.  Add code to
    display the warning.  (Bug#39180)
---
 lisp/progmodes/gdb-mi.el | 57 +++++++++++++++++++++++++++++++++++-------------
 1 file changed, 42 insertions(+), 15 deletions(-)

diff --git a/lisp/progmodes/gdb-mi.el b/lisp/progmodes/gdb-mi.el
index e785acd..da5a2a5 100644
--- a/lisp/progmodes/gdb-mi.el
+++ b/lisp/progmodes/gdb-mi.el
@@ -105,13 +105,24 @@
 (defvar speedbar-initial-expansion-list-name)
 (defvar speedbar-frame)
 
-(defvar        gdb-memory-address "main")
-(defvar        gdb-memory-last-address nil
+(defvar-local gdb-memory-address-expression "main"
+  "This expression is passed to gdb.
+Possible value: main, $rsp, x+3.")
+(defvar-local gdb-memory-address nil
+  "Address of memory display.")
+(defvar-local gdb-memory-last-address nil
   "Last successfully accessed memory address.")
 (defvar        gdb-memory-next-page nil
   "Address of next memory page for program memory buffer.")
 (defvar        gdb-memory-prev-page nil
   "Address of previous memory page for program memory buffer.")
+(defvar-local gdb--memory-display-warning nil
+  "Display warning on memory header if t.
+
+When error occurs when retrieving memory, gdb-mi displays the
+last successful page.  In that case the expression might not
+match the memory displayed.  We want to let the user be aware of
+that, so display a warning exclamation mark in the header line.")
 
 (defvar gdb-thread-number nil
   "Main current thread.
@@ -3450,7 +3461,7 @@ line."
 (def-gdb-trigger-and-handler
   gdb-invalidate-memory
   (format "-data-read-memory %s %s %d %d %d"
-          gdb-memory-address
+          (gdb-mi-quote gdb-memory-address-expression)
           gdb-memory-format
           gdb-memory-unit
           gdb-memory-rows
@@ -3490,6 +3501,9 @@ in `gdb-memory-format'."
          (err-msg (bindat-get-field res 'msg)))
     (if (not err-msg)
         (let ((memory (bindat-get-field res 'memory)))
+          (when gdb-memory-last-address
+            ;; Nil means last retrieve emits error or just started the session.
+            (setq gdb--memory-display-warning nil))
           (setq gdb-memory-address (bindat-get-field res 'addr))
           (setq gdb-memory-next-page (bindat-get-field res 'next-page))
           (setq gdb-memory-prev-page (bindat-get-field res 'prev-page))
@@ -3503,10 +3517,15 @@ in `gdb-memory-format'."
                                             gdb-memory-format)))))
             (newline)))
       ;; Show last page instead of empty buffer when out of bounds
-      (progn
-        (let ((gdb-memory-address gdb-memory-last-address))
+      (when gdb-memory-last-address
+        (let ((gdb-memory-address-expression gdb-memory-last-address))
+          ;; If we don't set `gdb-memory-last-address' to nil,
+          ;; `gdb-invalidate-memory' eventually calls
+          ;; `gdb-read-memory-custom', making an infinite loop.
+          (setq gdb-memory-last-address nil
+                gdb--memory-display-warning t)
           (gdb-invalidate-memory 'update)
-          (error err-msg))))))
+          (user-error "Error when retrieving memory: %s Displaying last 
successful page" err-msg))))))
 
 (defvar gdb-memory-mode-map
   (let ((map (make-sparse-keymap)))
@@ -3540,7 +3559,7 @@ in `gdb-memory-format'."
   "Set the start memory address."
   (interactive)
   (let ((arg (read-from-minibuffer "Memory address: ")))
-    (setq gdb-memory-address arg))
+    (setq gdb-memory-address-expression arg))
   (gdb-invalidate-memory 'update))
 
 (defmacro def-gdb-set-positive-number (name variable echo-string &optional doc)
@@ -3723,7 +3742,19 @@ DOC is an optional documentation string."
 (defvar gdb-memory-header
   '(:eval
     (concat
-     "Start address["
+     "Start address "
+     ;; If `gdb-memory-address-expression' is nil, `propertize' would error.
+     (propertize (or gdb-memory-address-expression "N/A")
+                 'face font-lock-warning-face
+                 'help-echo "mouse-1: set start address"
+                 'mouse-face 'mode-line-highlight
+                 'local-map (gdb-make-header-line-mouse-map
+                             'mouse-1
+                             #'gdb-memory-set-address-event))
+     (if gdb--memory-display-warning
+         (propertize " !" 'face '(:inherit error :weight bold))
+       "")
+     " ["
      (propertize "-"
                  'face font-lock-warning-face
                  'help-echo "mouse-1: decrement address"
@@ -3740,13 +3771,9 @@ DOC is an optional documentation string."
                              'mouse-1
                              #'gdb-memory-show-next-page))
      "]: "
-     (propertize gdb-memory-address
-                 'face font-lock-warning-face
-                 'help-echo "mouse-1: set start address"
-                 'mouse-face 'mode-line-highlight
-                 'local-map (gdb-make-header-line-mouse-map
-                             'mouse-1
-                             #'gdb-memory-set-address-event))
+     ;; If `gdb-memory-address' is nil, `propertize' would error.
+     (propertize (or gdb-memory-address "N/A")
+                 'face font-lock-warning-face)
      "  Rows: "
      (propertize (number-to-string gdb-memory-rows)
                  'face font-lock-warning-face