Handle escaped characters in Eshell argument predicates/modifiers

* lisp/eshell/em-pred.el (eshell-get-delimited-modifier-argument):
Unescape escaped characters.

* test/lisp/eshell/em-pred-tests.el (em-pred-test/predicate-escaping):
New test (bug#55204).

2 files changed, 15 insertions, 1 deletions

diff --git a/lisp/eshell/em-pred.el b/lisp/eshell/em-pred.el
index 594563554d2..d73976d3464 100644
--- a/lisp/eshell/em-pred.el
+++ b/lisp/eshell/em-pred.el
@@ -416,7 +416,9 @@ before the closing delimiter. This allows modifiers like
               (close (cdr (assoc open eshell-pred-delimiter-pairs)))
               (end (eshell-find-delimiter open close nil nil t)))
     (prog1
-        (buffer-substring-no-properties (1+ (point)) end)
+        (replace-regexp-in-string
+         (rx-to-string `(seq "\\" (group (or "\\" ,open ,close)))) "\\1"
+         (buffer-substring-no-properties (1+ (point)) end))
       (goto-char (if (and chained-p (eq open close))
                      end
                    (1+ end))))))
diff --git a/test/lisp/eshell/em-pred-tests.el b/test/lisp/eshell/em-pred-tests.el
index 4d2af392923..3b50543d69a 100644
--- a/test/lisp/eshell/em-pred-tests.el
+++ b/test/lisp/eshell/em-pred-tests.el
@@ -533,4 +533,16 @@ PREDICATE is the predicate used to query that attribute."
                     (format ":j%c-%c" (car delims) (cdr delims)))
                    "foo-bar-baz"))))
 
+(ert-deftest em-pred-test/predicate-escaping ()
+  "Test string escaping in predicate and modifier parameters."
+  ;; Escaping the delimiter should remove the backslash.
+  (should (equal (eshell-eval-predicate '("foo" "bar" "baz") ":j'\\''")
+                 "foo'bar'baz"))
+  ;; Escaping a backlash should remove the first backslash.
+  (should (equal (eshell-eval-predicate '("foo" "bar" "baz") ":j'\\\\'")
+                 "foo\\bar\\baz"))
+  ;; Escaping a different character should keep the backslash.
+  (should (equal (eshell-eval-predicate '("foo" "bar" "baz") ":j'\\\"'")
+                 "foo\\\"bar\\\"baz")))
+
 ;; em-pred-tests.el ends here