Avoid recomputing VCS in projectile-dir-files-alien

The dispatcher in `projectile-dir-files` already resolves the VCS for
the hybrid path. Thread it through to `projectile-dir-files-alien` via
a new optional argument so we don't pay for a second `projectile-project-vcs`
call on every indexing run. Single-argument callers (and the spies in
the test suite) keep working unchanged.

Also drop the post-hoc `(member local-f '("." ".."))` filter in
`projectile-index-directory` in favour of `directory-files`'
`directory-files-no-dot-files-regexp`, which handles the same case at
the C level.

2 files changed, 23 insertions, 14 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3e16240..8a7f0ce 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,8 @@
 
 ### Changes
 
+* `projectile-dir-files-alien` now accepts an optional `vcs` argument so the dispatcher can thread through the already-resolved VCS instead of recomputing it. Existing single-argument callers are unaffected.
+* `projectile-index-directory` (native indexing) now relies on `directory-files-no-dot-files-regexp` to filter out `.` and `..` at the C level instead of walking past them in Elisp.
 * `projectile-project-root-cache` now keys entries on cons cells (`(FUNC . DIR)` for per-function results, `('none . DIR)` for the overall failure marker) instead of formatted strings. This is internal state, but third-party code that reaches into the cache directly will need to update.
 * `projectile-parse-dirconfig-file' now returns a `projectile-dirconfig' struct (with `keep', `ignore', `ensure', and `prefixless-ignore' slots) instead of a positional 3-tuple. External callers should use the accessors (`projectile-dirconfig-keep' etc.) rather than `car'/`cadr'/`caddr'.
 * Soft-deprecate prefix-less ignore entries in `.projectile'. Lines without a `+'/`-'/`!' prefix are still treated as ignore patterns for backward compatibility, but a one-time warning is now shown for each project that uses them. Set `projectile-warn-on-prefixless-dirconfig-lines' to nil to silence.
diff --git a/projectile.el b/projectile.el
index bcdf1a3..638642e 100644
--- a/projectile.el
+++ b/projectile.el
@@ -1599,13 +1599,14 @@ Files are returned as relative paths to DIRECTORY."
                          (gethash directory projectile-projects-cache))))
     ;; cache disabled or cache miss
     (or files-list
-        (let ((vcs (projectile-project-vcs directory)))
-          (pcase projectile-indexing-method
-            ('native (projectile-dir-files-native directory))
-            ;; use external tools to get the project files
-            ('hybrid (projectile-adjust-files directory vcs (projectile-dir-files-alien directory)))
-            ('alien (projectile-dir-files-alien directory))
-            (_ (user-error "Unsupported indexing method `%S'" projectile-indexing-method)))))))
+        (pcase projectile-indexing-method
+          ('native (projectile-dir-files-native directory))
+          ;; use external tools to get the project files
+          ('hybrid (let ((vcs (projectile-project-vcs directory)))
+                     (projectile-adjust-files directory vcs
+                                              (projectile-dir-files-alien directory vcs))))
+          ('alien (projectile-dir-files-alien directory))
+          (_ (user-error "Unsupported indexing method `%S'" projectile-indexing-method))))))
 
 ;;; Native Project Indexing
 ;;
@@ -1637,8 +1638,7 @@ IGNORED-DIRECTORIES may optionally be provided."
            (mapcar
             (lambda (f)
               (let ((local-f (file-name-nondirectory (directory-file-name f))))
-                (unless (or (and patterns (projectile-ignored-rel-p f directory patterns))
-                            (member local-f '("." "..")))
+                (unless (and patterns (projectile-ignored-rel-p f directory patterns))
                   (progress-reporter-update progress-reporter)
                   (if (file-directory-p f)
                       (unless (projectile-ignored-directory-p
@@ -1651,17 +1651,24 @@ IGNORED-DIRECTORIES may optionally be provided."
                       (list f))))))
             ;; Use ignore-errors to skip unreadable directories (e.g.
             ;; .Spotlight-V100 on macOS) instead of aborting the entire
-            ;; indexing operation.
-            (ignore-errors (directory-files directory t))))))
+            ;; indexing operation.  `directory-files-no-dot-files-regexp'
+            ;; filters out . and .. at the C level so we don't have to
+            ;; do it again in the loop.
+            (ignore-errors
+              (directory-files directory t directory-files-no-dot-files-regexp))))))
 
 ;;; Alien Project Indexing
 ;;
 ;; This corresponds to `projectile-indexing-method' being set to hybrid or alien.
 ;; The only difference between the two methods is that alien doesn't do
 ;; any post-processing of the files obtained via the external command.
-(defun projectile-dir-files-alien (directory)
-  "Get the files for DIRECTORY using external tools."
-  (let ((vcs (projectile-project-vcs directory)))
+(defun projectile-dir-files-alien (directory &optional vcs)
+  "Get the files for DIRECTORY using external tools.
+VCS, when supplied, must be the project's VCS as returned by
+`projectile-project-vcs'.  It is computed from DIRECTORY when
+omitted; callers that already resolved the VCS can pass it in to
+avoid the redundant work."
+  (let ((vcs (or vcs (projectile-project-vcs directory))))
     (cond
      ((eq vcs 'git)
       (let* ((files (nconc (projectile-files-via-ext-command directory (projectile-get-ext-command vcs))