Keep subcommands in pipelines from clobbering the head/tail processes

* lisp/eshell/esh-cmd.el (eshell-execute-pipeline): Use 'make-symbol'
for headproc and tailproc.
(eshell-do-pipelines, eshell-do-pipelines-synchronously): Adapt to the
above.

* test/lisp/eshell/eshell-tests.el (eshell-test/pipe-subcommand)
(eshell-test/pipe-subcommand-with-pipe): New test.

* doc/misc/eshell.texi (Bugs and ideas): Remove item about piping to
process from loop; this commit fixes it (bug#55590).

1 files changed, 16 insertions, 0 deletions

diff --git a/test/lisp/eshell/eshell-tests.el b/test/lisp/eshell/eshell-tests.el
index 7cdeb017e44..c0affed80aa 100644
--- a/test/lisp/eshell/eshell-tests.el
+++ b/test/lisp/eshell/eshell-tests.el
@@ -114,6 +114,22 @@ e.g. \"{(+ 1 2)} 3\" => 3"
    (eshell-wait-for-subprocess)
    (eshell-match-result "OLLEH\n")))
 
+(ert-deftest eshell-test/pipe-subcommand ()
+  "Check that piping with an asynchronous subcommand works"
+  (skip-unless (and (executable-find "echo")
+                    (executable-find "cat")))
+  (with-temp-eshell
+   (eshell-command-result-p "echo ${*echo hi} | *cat"
+                            "hi")))
+
+(ert-deftest eshell-test/pipe-subcommand-with-pipe ()
+  "Check that piping with an asynchronous subcommand with its own pipe works"
+  (skip-unless (and (executable-find "echo")
+                    (executable-find "cat")))
+  (with-temp-eshell
+   (eshell-command-result-p "echo ${*echo hi | *cat} | *cat"
+                            "hi")))
+
 (ert-deftest eshell-test/redirect-buffer ()
   "Check that piping to a buffer works"
   (with-temp-buffer