Simplify parsing subcommands slightly

This mainly reduces some overly-deep indentation, but also fixes some
minor issues with the "$<subcmd>" form: it unnecessarily added " >
TEMP" (we already set this later via 'eshell-create-handles'), and it
didn't properly unescape inner double quotes.

* lisp/eshell/esh-cmd.el (eshell-parse-subcommand-argument): Simplify.

* lisp/eshell/esh-var.el (eshell-parse-variable-ref): Simplify and
fix edge cases in "$<subcmd>".

* test/lisp/eshell/esh-var-tests.el
(esh-var-test/quoted-interp-temp-cmd): Adjust test to check behavior
of inner double quotes.

3 files changed, 56 insertions, 55 deletions

diff --git a/lisp/eshell/esh-cmd.el b/lisp/eshell/esh-cmd.el
index e0651b76249..1a458290dfe 100644
--- a/lisp/eshell/esh-cmd.el
+++ b/lisp/eshell/esh-cmd.el
@@ -675,13 +675,13 @@ This means an exit code of 0."
            (or (= (point-max) (1+ (point)))
                (not (eq (char-after (1+ (point))) ?\}))))
       (let ((end (eshell-find-delimiter ?\{ ?\})))
-        (if (not end)
-            (throw 'eshell-incomplete "{")
-          (when (eshell-arg-delimiter (1+ end))
-            (prog1
-                `(eshell-as-subcommand
-                  ,(eshell-parse-command (cons (1+ (point)) end)))
-              (goto-char (1+ end))))))))
+        (unless end
+          (throw 'eshell-incomplete "{"))
+        (when (eshell-arg-delimiter (1+ end))
+          (prog1
+              `(eshell-as-subcommand
+                ,(eshell-parse-command (cons (1+ (point)) end)))
+            (goto-char (1+ end)))))))
 
 (defun eshell-parse-lisp-argument ()
   "Parse a Lisp expression which is specified as an argument."
diff --git a/lisp/eshell/esh-var.el b/lisp/eshell/esh-var.el
index 5d6299af564..7dcaff1e24f 100644
--- a/lisp/eshell/esh-var.el
+++ b/lisp/eshell/esh-var.el
@@ -507,55 +507,56 @@ Possible variable references are:
   (cond
    ((eq (char-after) ?{)
     (let ((end (eshell-find-delimiter ?\{ ?\})))
-      (if (not end)
-          (throw 'eshell-incomplete "${")
-        (forward-char)
-        (prog1
-            `(eshell-apply-indices
-              (eshell-convert
-               (eshell-command-to-value
-                (eshell-as-subcommand
-                 ,(let ((subcmd (or (eshell-unescape-inner-double-quote end)
-                                    (cons (point) end)))
-                        (eshell-current-quoted nil))
-                    (eshell-parse-command subcmd))))
-               ;; If this is a simple double-quoted form like
-               ;; "${COMMAND}" (i.e. no indices after the subcommand
-               ;; and no `#' modifier before), ensure we convert to a
-               ;; single string.  This avoids unnecessary work
-               ;; (e.g. splitting the output by lines) when it would
-               ;; just be joined back together afterwards.
-               ,(when (and (not modifier-p) eshell-current-quoted)
-                  '(not indices)))
-              indices ,eshell-current-quoted)
-          (goto-char (1+ end))))))
+      (unless end
+        (throw 'eshell-incomplete "${"))
+      (forward-char)
+      (prog1
+          `(eshell-apply-indices
+            (eshell-convert
+             (eshell-command-to-value
+              (eshell-as-subcommand
+               ,(let ((subcmd (or (eshell-unescape-inner-double-quote end)
+                                  (cons (point) end)))
+                      (eshell-current-quoted nil))
+                  (eshell-parse-command subcmd))))
+             ;; If this is a simple double-quoted form like
+             ;; "${COMMAND}" (i.e. no indices after the subcommand and
+             ;; no `#' modifier before), ensure we convert to a single
+             ;; string.  This avoids unnecessary work (e.g. splitting
+             ;; the output by lines) when it would just be joined back
+             ;; together afterwards.
+             ,(when (and (not modifier-p) eshell-current-quoted)
+                '(not indices)))
+            indices ,eshell-current-quoted)
+        (goto-char (1+ end)))))
    ((eq (char-after) ?\<)
     (let ((end (eshell-find-delimiter ?\< ?\>)))
-      (if (not end)
-          (throw 'eshell-incomplete "$<")
-        (let* ((temp (make-temp-file temporary-file-directory))
-               (cmd (concat (buffer-substring (1+ (point)) end)
-                            " > " temp)))
-          (prog1
-              `(let ((eshell-current-handles
-                      (eshell-create-handles ,temp 'overwrite)))
-                 (progn
-                   (eshell-as-subcommand
-                    ,(let ((eshell-current-quoted nil))
-                       (eshell-parse-command cmd)))
-                   (ignore
-                    (nconc eshell-this-command-hook
-                           ;; Quote this lambda; it will be evaluated
-                           ;; by `eshell-do-eval', which requires very
-                           ;; particular forms in order to work
-                           ;; properly.  See bug#54190.
-                           (list (function
-                                  (lambda ()
-                                    (delete-file ,temp)
-                                    (when-let ((buffer (get-file-buffer ,temp)))
-                                      (kill-buffer buffer)))))))
-                   (eshell-apply-indices ,temp indices ,eshell-current-quoted)))
-            (goto-char (1+ end)))))))
+      (unless end
+        (throw 'eshell-incomplete "$<"))
+      (forward-char)
+      (let* ((temp (make-temp-file temporary-file-directory))
+             (subcmd (or (eshell-unescape-inner-double-quote end)
+                         (cons (point) end))))
+        (prog1
+            `(let ((eshell-current-handles
+                    (eshell-create-handles ,temp 'overwrite)))
+               (progn
+                 (eshell-as-subcommand
+                  ,(let ((eshell-current-quoted nil))
+                     (eshell-parse-command subcmd)))
+                 (ignore
+                  (nconc eshell-this-command-hook
+                         ;; Quote this lambda; it will be evaluated by
+                         ;; `eshell-do-eval', which requires very
+                         ;; particular forms in order to work
+                         ;; properly.  See bug#54190.
+                         (list (function
+                                (lambda ()
+                                  (delete-file ,temp)
+                                  (when-let ((buffer (get-file-buffer ,temp)))
+                                    (kill-buffer buffer)))))))
+                 (eshell-apply-indices ,temp indices ,eshell-current-quoted)))
+          (goto-char (1+ end))))))
    ((eq (char-after) ?\()
     (condition-case nil
         `(eshell-apply-indices
diff --git a/test/lisp/eshell/esh-var-tests.el b/test/lisp/eshell/esh-var-tests.el
index 6767d9289f9..771bd5a419c 100644
--- a/test/lisp/eshell/esh-var-tests.el
+++ b/test/lisp/eshell/esh-var-tests.el
@@ -454,7 +454,7 @@ nil, use FUNCTION instead."
   (let ((temporary-file-directory
          (file-name-as-directory (make-temp-file "esh-vars-tests" t))))
     (unwind-protect
-        (eshell-command-result-equal "cat \"$<echo hi>\"" "hi")
+        (eshell-command-result-equal "cat \"$<echo \\\"hi\\\">\"" "hi")
       (delete-directory temporary-file-directory t))))
 
 (ert-deftest esh-var-test/quoted-interp-concat-cmd ()