Use 'unwind-protect' in more places in Eshell

This lets us simplify the logic for how we reset
'eshell-current-command' and 'eshell-last-async-procs', as well as
improving correctness of Eshell command forms in a few esoteric
scenarios.  Additionally, this helps set the stage for better support
of background commands in Eshell (bug#66164).

* lisp/eshell/esh-cmd.el (eshell-cmd-initialize): Remove addition to
'eshell-post-command-hook'; this is handled in 'eshell-resume-command'
and 'eshell-resume-eval' now.
(eshell-resume-command): Handle resetting the prompt as needed.
(eshell-resume-eval): Use 'unwind-protect' to ensure that we set
'eshell-last-async-procs' and 'eshell-current-comment' at the right
times.
(eshell-parse-command, eshell-trap-errors, eshell-manipulate): Use
'unwind-protect'.
(eshell-do-eval): Allow 'eshell-defer' to pass through
'unwind-protect' forms without actually calling the unwinding forms
(yet).

* lisp/eshell/esh-proc.el (eshell-kill-process-function)
(eshell-reset-after-proc): Make obsolete.  The behavior is now handled
in 'eshell-resume-command'.
(eshell-gather-process-output, eshell-sentinel)
(eshell-interrupt-process, eshell-kill-process, eshell-quit-process)
(eshell-stop-process, eshell-continue-process): Run 'eshell-kill-hook'
directly.

* test/lisp/eshell/esh-cmd-tests.el (esh-cmd-test/throw): New test.

1 files changed, 16 insertions, 0 deletions

diff --git a/test/lisp/eshell/esh-cmd-tests.el b/test/lisp/eshell/esh-cmd-tests.el
index 7c384471e93..643038f89ff 100644
--- a/test/lisp/eshell/esh-cmd-tests.el
+++ b/test/lisp/eshell/esh-cmd-tests.el
@@ -442,4 +442,20 @@ This tests when `eshell-lisp-form-nil-is-failure' is nil."
   (eshell-command-result-equal "unless {[ foo = bar ]} {echo no} {echo yes}"
                                "no"))
 
+
+;; Error handling
+
+(ert-deftest esh-cmd-test/throw ()
+  "Test that calling `throw' as an Eshell command unwinds everything properly."
+  (with-temp-eshell
+   (should (= (catch 'tag
+                (eshell-insert-command
+                 "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)
+   ;; Make sure we can call another command after throwing.
+   (eshell-match-command-output "echo again" "\\`again\n")))
+
 ;; esh-cmd-tests.el ends here