Allow using a symbol as an index into an alist in Eshell

* lisp/eshell/esh-var.el (eshell-index-value): If INDEX is a symbol,
use 'assoc' for indexing.

* test/lisp/eshell/esh-var-tests.el (esh-var-test/interp-var-assoc)
(esh-var-test/quoted-interp-var-assoc): Add checks for indexing via
symbol (bug#57787).

2 files changed, 26 insertions, 21 deletions

diff --git a/lisp/eshell/esh-var.el b/lisp/eshell/esh-var.el
index a9df172e88e..36e59cd5a41 100644
--- a/lisp/eshell/esh-var.el
+++ b/lisp/eshell/esh-var.el
@@ -646,23 +646,24 @@ For example, to retrieve the second element of a user's record in
   "Reference VALUE using the given INDEX."
   (when (and (stringp index) (get-text-property 0 'number index))
     (setq index (string-to-number index)))
-  (if (stringp index)
-      (cdr (assoc index value))
-    (cond
-     ((ring-p value)
-      (if (> index (ring-length value))
-          (error "Index exceeds length of ring")
-        (ring-ref value index)))
-     ((listp value)
-      (if (> index (length value))
-          (error "Index exceeds length of list")
-        (nth index value)))
-     ((vectorp value)
-      (if (> index (length value))
-          (error "Index exceeds length of vector")
-        (aref value index)))
-     (t
-      (error "Invalid data type for indexing")))))
+  (if (integerp index)
+      (cond
+       ((ring-p value)
+        (if (> index (ring-length value))
+            (error "Index exceeds length of ring")
+          (ring-ref value index)))
+       ((listp value)
+        (if (> index (length value))
+            (error "Index exceeds length of list")
+          (nth index value)))
+       ((vectorp value)
+        (if (> index (length value))
+            (error "Index exceeds length of vector")
+          (aref value index)))
+       (t
+        (error "Invalid data type for indexing")))
+    ;; INDEX is some non-integer value, so treat VALUE as an alist.
+    (cdr (assoc index value))))
 
 ;;;_* Variable name completion
 
diff --git a/test/lisp/eshell/esh-var-tests.el b/test/lisp/eshell/esh-var-tests.el
index bebc57d3592..cb5b1766bb5 100644
--- a/test/lisp/eshell/esh-var-tests.el
+++ b/test/lisp/eshell/esh-var-tests.el
@@ -105,9 +105,11 @@
 
 (ert-deftest esh-var-test/interp-var-assoc ()
   "Interpolate alist variable with index"
-  (let ((eshell-test-value '(("foo" . 1))))
+  (let ((eshell-test-value '(("foo" . 1) (bar . 2))))
     (eshell-command-result-equal "echo $eshell-test-value[foo]"
-                                 1)))
+                                 1)
+    (eshell-command-result-equal "echo $eshell-test-value[#'bar]"
+                                 2)))
 
 (ert-deftest esh-var-test/interp-var-length-list ()
   "Interpolate length of list variable"
@@ -257,9 +259,11 @@ inside double-quotes"
 
 (ert-deftest esh-var-test/quoted-interp-var-assoc ()
   "Interpolate alist variable with index inside double-quotes"
-  (let ((eshell-test-value '(("foo" . 1))))
+  (let ((eshell-test-value '(("foo" . 1) (bar . 2))))
     (eshell-command-result-equal "echo \"$eshell-test-value[foo]\""
-                                 "1")))
+                                 "1")
+    (eshell-command-result-equal "echo \"$eshell-test-value[#'bar]\""
+                                 "2")))
 
 (ert-deftest esh-var-test/quoted-interp-var-length-list ()
   "Interpolate length of list variable inside double-quotes"