helpful

commit 7e4b1f0d5572a4e2b8ee7a9b084ef863d0315a73
parent 716c116d6a9fafb16a5b1e6be5dbd8e82f357c7e
Author: Dario Gjorgjevski <dario.gjorgjevski+git@gmail.com>
Date:   Tue,  2 Feb 2021 17:54:44 +0100

Prevent error in helpful-variable if sexp at point can't be read

How to reproduce from emacs -Q in the *scratch* buffer:

0. If needed, do `(package-initialize)` and `(require 'helpful)`.
1. Type `(something some-undefined-variable|` where | represents
   point.  (Note that there is no closing parenthesis!)
2. Call helpful-variable.

This will give you an `End of file during parsing` from
`helpful--variable-defined-at-point` because the sexp at point can't
be read due to the missing parenthesis.  This commit suppresses the
error

Fix #251
Close #254

Diffstat:
M
CHANGELOG.md
 | 
3
+++
M
helpful.el
 | 
4
+++-
M
test/helpful-unit-test.el
 | 
12
++++++++++++

3 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -5,6 +5,9 @@ been loaded by the autoloader (#179, #191).
 
 Fixed issue with displaying circular data structures.
 
+Fixed a crash in `helpful-variable` in files that weren't
+syntactically valid lisp.
+
 # v0.18
 
 Show the original value for custom variables whose value has changed.
diff --git a/helpful.el b/helpful.el
@@ -2738,7 +2738,9 @@ See also `helpful-callable' and `helpful-variable'."
              sexp)
         (when sexp-start
           (goto-char sexp-start)
-          (setq sexp (read (current-buffer)))
+          (setq sexp (condition-case nil
+                         (read (current-buffer))
+                       (error nil)))
           (when (memq (car-safe sexp)
                       (list 'defvar 'defvar-local 'defcustom 'defconst))
             (nth 1 sexp)))))))
diff --git a/test/helpful-unit-test.el b/test/helpful-unit-test.el
@@ -133,6 +133,18 @@ bar")))
     (helpful-function #'test-foo-defined-interactively)
     (should (equal (buffer-name) "*helpful function: test-foo-defined-interactively*"))))
 
+(ert-deftest helpful--variable-defined-at-point ()
+  ;; The happy case with valid code.
+  (with-temp-buffer
+    (insert "(defvar foo nil)")
+    (goto-char (1+ (point-min)))
+    (should (eq (helpful--variable-defined-at-point) 'foo)))
+  ;; Ensure we don't crash if the source code isn't valid.
+  (with-temp-buffer
+    (insert "(defvar foo nil")
+    (goto-char (1+ (point-min)))
+    (helpful--variable-defined-at-point)))
+
 (ert-deftest helpful--edebug-fn ()
   "We should not crash on a function with edebug enabled."
   (let ((edebug-all-forms t)