master 1480865e64 3/4: Warn about `ignore-error` with quoted condition argument

[Mattias Engdegård]

branch: master
commit 1480865e641b06d570f5ab56011f8e3e5481da7d
Author: Mattias Engdegård <mattiase@acm.org>
Commit: Mattias Engdegård <mattiase@acm.org>

    Warn about `ignore-error` with quoted condition argument
    
    * lisp/subr.el (ignore-error):
    Clarify condition argument in doc string and add warning.
    * test/lisp/emacs-lisp/bytecomp-tests.el
    (bytecomp-warn-quoted-condition): New test.
---
 lisp/subr.el                           | 13 +++++++++++--
 test/lisp/emacs-lisp/bytecomp-tests.el |  5 +++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/lisp/subr.el b/lisp/subr.el
index f0081de061..5e8f3c82a2 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -380,9 +380,18 @@ without silencing all errors."
   "Execute BODY; if the error CONDITION occurs, return nil.
 Otherwise, return result of last form in BODY.
 
-CONDITION can also be a list of error conditions."
+CONDITION can also be a list of error conditions.
+The CONDITION argument is not evaluated.  Do not quote it."
   (declare (debug t) (indent 1))
-  `(condition-case nil (progn ,@body) (,condition nil)))
+  (if (and (eq (car-safe condition) 'quote)
+           (cdr condition) (null (cddr condition)))
+      (macroexp-warn-and-return
+       (format "`ignore-error' condition argument should not be quoted: %S"
+               condition)
+       `(condition-case nil (progn ,@body) (,(cadr condition) nil))
+       nil t condition)
+    `(condition-case nil (progn ,@body) (,condition nil))))
+
 
 ;;;; Basic Lisp functions.
 
diff --git a/test/lisp/emacs-lisp/bytecomp-tests.el 
b/test/lisp/emacs-lisp/bytecomp-tests.el
index 47200de7a0..0d62283c04 100644
--- a/test/lisp/emacs-lisp/bytecomp-tests.el
+++ b/test/lisp/emacs-lisp/bytecomp-tests.el
@@ -922,6 +922,11 @@ byte-compiled.  Run with dynamic binding."
   (bytecomp--with-warning-test "defvar.*foo.*wider than.*characters"
     `(defvar foo t ,bytecomp-tests--docstring)))
 
+(ert-deftest bytecomp-warn-quoted-condition ()
+  (bytecomp--with-warning-test
+      "Warning: `ignore-error' condition argument should not be quoted: 'error"
+    '(ignore-error 'error (abc))))
+
 (ert-deftest bytecomp-warn-dodgy-args-eq ()
   (dolist (fn '(eq eql))
     (cl-flet ((msg (type arg)