Support Eshell iterative evaluation in the background

This really just generalizes Eshell's previous support for iterative
evaluation of a single current command to a list of multiple commands,
of which at most one can be in the foreground (bug#66066).

* lisp/eshell/esh-cmd.el (eshell-last-async-procs)
(eshell-current-command): Make obsolete in favor of...
(eshell-foreground-command): ... this
(eshell-background-commands): New variable.
(eshell-interactive-process-p): Make obsolete.
(eshell-head-process, eshell-tail-process): Use
'eshell-foreground-command'.
(eshell-cmd-initialize): Initialize new variables.
(eshell-add-command, eshell-remove-command)
(eshell-commands-for-process): New functions.
(eshell-parse-command): Make 'eshell-do-subjob' the outermost call.
(eshell-do-subjob): Call 'eshell-resume-eval' to split this command
off from its parent forms.
(eshell-eval-command): Use 'eshell-add-command'.
(eshell-resume-command): Use 'eshell-commands-for-process'.
(eshell-resume-eval): Take a COMMAND argument.  Return
':eshell-background' form for deferred background commands.
(eshell-do-eval): Remove check for 'eshell-current-subjob-p'.  This is
handled differently now.

* lisp/eshell/eshell.el (eshell-command): Wait for all processes to
exit when running synchronously.

* lisp/eshell/esh-mode.el (eshell-intercept-commands)
(eshell-watch-for-password-prompt):
* lisp/eshell/em-cmpl.el (eshell-complete-parse-arguments):
* lisp/eshell/em-smart.el (eshell-smart-display-move): Use
'eshell-foreground-command'.

* test/lisp/eshell/esh-cmd-tests.el
(esh-cmd-test/background/simple-command)
(esh-cmd-test/background/subcommand): New tests.
(esh-cmd-test/throw): Use 'eshell-foreground-command'.

* test/lisp/eshell/eshell-tests.el (eshell-test/queue-input): Use
'eshell-foreground-command'.

* test/lisp/eshell/em-script-tests.el
(em-script-test/source-script/background): Make the test script more
complex.

* test/lisp/eshell/eshell-tests.el
(eshell-test/eshell-command/pipeline-wait): New test.

* doc/misc/eshell.texi (Bugs and ideas): Remove implemented feature.

3 files changed, 42 insertions, 5 deletions

diff --git a/test/lisp/eshell/em-script-tests.el b/test/lisp/eshell/em-script-tests.el
index 191755dcc3e..02e4125d827 100644
--- a/test/lisp/eshell/em-script-tests.el
+++ b/test/lisp/eshell/em-script-tests.el
@@ -67,14 +67,14 @@
   "Test sourcing a script in the background."
   (skip-unless (executable-find "echo"))
   (ert-with-temp-file temp-file
-    :text "*echo hi"
+    :text "*echo hi\nif {[ foo = foo ]} {*echo bye}"
     (eshell-with-temp-buffer bufname "old"
       (with-temp-eshell
        (eshell-match-command-output
         (format "source %s > #<%s> &" temp-file bufname)
         "\\`\\'")
        (eshell-wait-for-subprocess t))
-      (should (equal (buffer-string) "hi\n")))))
+      (should (equal (buffer-string) "hi\nbye\n")))))
 
 (ert-deftest em-script-test/source-script/arg-vars ()
   "Test sourcing script with $0, $1, ... variables."
diff --git a/test/lisp/eshell/esh-cmd-tests.el b/test/lisp/eshell/esh-cmd-tests.el
index 643038f89ff..e0783b26ad6 100644
--- a/test/lisp/eshell/esh-cmd-tests.el
+++ b/test/lisp/eshell/esh-cmd-tests.el
@@ -104,6 +104,32 @@ bug#59469."
     "value\nexternal\nvalue\n")))
 
 
+;; Background command invocation
+
+(ert-deftest esh-cmd-test/background/simple-command ()
+  "Test invocation with a simple background command."
+  (skip-unless (executable-find "echo"))
+  (eshell-with-temp-buffer bufname ""
+    (with-temp-eshell
+     (eshell-match-command-output
+      (format "*echo hi > #<%s> &" bufname)
+      (rx "[echo" (? ".exe") "] " (+ digit) "\n"))
+     (eshell-wait-for-subprocess t))
+    (should (equal (buffer-string) "hi\n"))))
+
+(ert-deftest esh-cmd-test/background/subcommand ()
+  "Test invocation with a background command containing subcommands."
+  (skip-unless (and (executable-find "echo")
+                    (executable-find "rev")))
+  (eshell-with-temp-buffer bufname ""
+    (with-temp-eshell
+     (eshell-match-command-output
+      (format "*echo ${*echo hello | rev} > #<%s> &" bufname)
+      (rx "[echo" (? ".exe") "] " (+ digit) "\n"))
+     (eshell-wait-for-subprocess t))
+    (should (equal (buffer-string) "olleh\n"))))
+
+
 ;; Lisp forms
 
 (ert-deftest esh-cmd-test/quoted-lisp-form ()
@@ -453,8 +479,7 @@ This tests when `eshell-lisp-form-nil-is-failure' is nil."
                  "echo hi; (throw 'tag 42); echo bye"))
               42))
    (should (eshell-match-output "\\`hi\n\\'"))
-   (should-not eshell-current-command)
-   (should-not eshell-last-async-procs)
+   (should-not eshell-foreground-command)
    ;; Make sure we can call another command after throwing.
    (eshell-match-command-output "echo again" "\\`again\n")))
 
diff --git a/test/lisp/eshell/eshell-tests.el b/test/lisp/eshell/eshell-tests.el
index 25c8cfd389c..b02e5fca592 100644
--- a/test/lisp/eshell/eshell-tests.el
+++ b/test/lisp/eshell/eshell-tests.el
@@ -58,6 +58,18 @@ This test uses a pipeline for the command."
         (eshell-command "*echo hi | *cat" t)
         (should (equal (buffer-string) "hi\n"))))))
 
+(ert-deftest eshell-test/eshell-command/pipeline-wait ()
+  "Check that `eshell-command' waits for all its processes before returning."
+  (skip-unless (and (executable-find "echo")
+                    (executable-find "sh")
+                    (executable-find "rev")))
+  (ert-with-temp-directory eshell-directory-name
+    (let ((eshell-history-file-name nil))
+      (with-temp-buffer
+        (eshell-command
+         "*echo hello | sh -c 'sleep 1; rev' 1>&2 | *echo goodbye" t)
+        (should (equal (buffer-string) "goodbye\nolleh\n"))))))
+
 (ert-deftest eshell-test/eshell-command/background ()
   "Test that `eshell-command' works for background commands."
   (skip-unless (executable-find "echo"))
@@ -132,7 +144,7 @@ insert the queued one at the next prompt, and finally run it."
    (eshell-insert-command "sleep 1; echo slept")
    (eshell-insert-command "echo alpha" #'eshell-queue-input)
    (let ((start (marker-position (eshell-beginning-of-output))))
-     (eshell-wait-for (lambda () (not eshell-current-command)))
+     (eshell-wait-for (lambda () (not eshell-foreground-command)))
      (should (string-match "^slept\n.*echo alpha\nalpha\n$"
                            (buffer-substring-no-properties
                             start (eshell-end-of-output)))))))