* lisp/eshell/em-cmpl.el: Try and fix bug#41423

(eshell--complete-commands-list): Rename from `eshell-complete-commands-list`.
Return a (dynamic) completion table rather than a list of completions.
Use `dolist` and `push`.

1 files changed, 60 insertions, 58 deletions

diff --git a/lisp/eshell/em-cmpl.el b/lisp/eshell/em-cmpl.el
index 0200631da66..e0b3ab1ecf4 100644
--- a/lisp/eshell/em-cmpl.el
+++ b/lisp/eshell/em-cmpl.el
@@ -211,7 +211,7 @@ to writing a completion function."
 
 (defcustom eshell-command-completion-function
   (lambda ()
-    (pcomplete-here (eshell-complete-commands-list)))
+    (pcomplete-here (eshell--complete-commands-list)))
   (eshell-cmpl--custom-variable-docstring 'pcomplete-command-completion-function)
   :type (get 'pcomplete-command-completion-function 'custom-type)
   :group 'eshell-cmpl)
@@ -403,64 +403,66 @@ to writing a completion function."
            args)
           posns)))
 
-(defun eshell-complete-commands-list ()
+(defun eshell--complete-commands-list ()
   "Generate list of applicable, visible commands."
-  (let ((filename (pcomplete-arg)) glob-name)
-    (if (file-name-directory filename)
-        (if eshell-force-execution
-            (pcomplete-dirs-or-entries nil #'file-readable-p)
-          (pcomplete-executables))
-      (if (and (> (length filename) 0)
-               (eq (aref filename 0) eshell-explicit-command-char))
-          (setq filename (substring filename 1)
-                pcomplete-stub filename
-                glob-name t))
-      (let* ((paths (eshell-get-path))
-             (cwd (file-name-as-directory
-                   (expand-file-name default-directory)))
-             (path "") (comps-in-path ())
-             (file "") (filepath "") (completions ()))
-        ;; Go thru each path in the search path, finding completions.
-        (while paths
-          (setq path (file-name-as-directory
-                      (expand-file-name (or (car paths) ".")))
-                comps-in-path
-                (and (file-accessible-directory-p path)
-                     (file-name-all-completions filename path)))
-          ;; Go thru each completion found, to see whether it should
-          ;; be used.
-          (while comps-in-path
-            (setq file (car comps-in-path)
-                  filepath (concat path file))
-            (if (and (not (member file completions)) ;
-                     (or (string-equal path cwd)
-                         (not (file-directory-p filepath)))
-                     (if eshell-force-execution
-                         (file-readable-p filepath)
-                       (file-executable-p filepath)))
-                (setq completions (cons file completions)))
-            (setq comps-in-path (cdr comps-in-path)))
-          (setq paths (cdr paths)))
-        ;; Add aliases which are currently visible, and Lisp functions.
-        (pcomplete-uniquify-list
-         (if glob-name
-             completions
-           (setq completions
-                 (append (if (fboundp 'eshell-alias-completions)
-                              (eshell-alias-completions filename))
-                         (eshell-winnow-list
-                          (mapcar
-                           (lambda (name)
-                             (substring name 7))
-                           (all-completions (concat "eshell/" filename)
-                                            obarray #'functionp))
-                          nil '(eshell-find-alias-function))
-                         completions))
-           (append (and (or eshell-show-lisp-completions
-                            (and eshell-show-lisp-alternatives
-                                 (null completions)))
-                        (all-completions filename obarray #'functionp))
-                   completions)))))))
+  ;; Building the commands list can take quite a while, especially over Tramp
+  ;; (bug#41423), so do it lazily.
+  (completion-table-dynamic
+   (lambda (filename)
+     (if (file-name-directory filename)
+         (if eshell-force-execution
+             (pcomplete-dirs-or-entries nil #'file-readable-p)
+           (pcomplete-executables))
+       (let (glob-name)
+         (if (and (> (length filename) 0)
+                  (eq (aref filename 0) eshell-explicit-command-char))
+             ;; FIXME: Shouldn't we handle this `*' outside of the
+             ;; `pcomplete-here' in `eshell-command-completion-function'?
+             (setq filename (substring filename 1)
+                   pcomplete-stub filename
+                   glob-name t))
+         (let* ((paths (eshell-get-path))
+                (cwd (file-name-as-directory
+                      (expand-file-name default-directory)))
+                (filepath "") (completions ()))
+           ;; Go thru each path in the search path, finding completions.
+           (dolist (path paths)
+             (setq path (file-name-as-directory
+                         (expand-file-name (or path "."))))
+             ;; Go thru each completion found, to see whether it should
+             ;; be used.
+             (dolist (file (and (file-accessible-directory-p path)
+                                (file-name-all-completions filename path)))
+               (setq filepath (concat path file))
+               (if (and (not (member file completions)) ;
+                        (or (string-equal path cwd)
+                            (not (file-directory-p filepath)))
+                        ;; FIXME: Those repeated file tests end up
+                        ;; very costly over Tramp, we should cache the result.
+                        (if eshell-force-execution
+                            (file-readable-p filepath)
+                          (file-executable-p filepath)))
+                   (push file completions))))
+           ;; Add aliases which are currently visible, and Lisp functions.
+           (pcomplete-uniquify-list
+            (if glob-name
+                completions
+              (setq completions
+                    (append (if (fboundp 'eshell-alias-completions)
+                                (eshell-alias-completions filename))
+                            (eshell-winnow-list
+                             (mapcar
+                              (lambda (name)
+                                (substring name 7))
+                              (all-completions (concat "eshell/" filename)
+                                               obarray #'functionp))
+                             nil '(eshell-find-alias-function))
+                            completions))
+              (append (and (or eshell-show-lisp-completions
+                               (and eshell-show-lisp-alternatives
+                                    (null completions)))
+                           (all-completions filename obarray #'functionp))
+                      completions)))))))))
 
 (define-obsolete-function-alias 'eshell-pcomplete #'completion-at-point "27.1")