bug#48471: 28.0.50; Incorrect handling of `project-ignores' on macOS (BSD find?) if project root is a directory name

[Philipp <p.stephani2@gmail.com>]

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> Am 17.05.2021 um 21:37 schrieb Philipp <p.stephani2@gmail.com>:
> 
> 
> 
>> Am 17.05.2021 um 02:23 schrieb Dmitry Gutov <dgutov@yandex.ru>:
>> 
>> Hi!
>> 
>> On 16.05.2021 23:05, Philipp wrote:
>>> To work around this, XRef should probably only pass directory file names
>>> to find, not directory names, at least on macOS.
>> 
>> Could you track down the piece of code that's misbehaving? Maybe with a little edebug-ing.
>> 
>> I don't have any BSD find at hand, but
>> 
>> (xref--find-ignores-arguments '("./bar") "/tmp/foo/")
>> 
>> returns
>> 
>> "\\( -path /tmp/foo/bar \\) -prune -o "
>> 
>> here.
> 
> Yes, and that's the problem.  macOS find compares the "-path" value against /tmp/foo//bar (note the double slash), and that doesn't match.  The exact shell command generated by project--files-in-directory is:
> 
>  find /tmp/foo/ \( -path /tmp/foo/bar \) -prune -o  -type f  -print0
> 
> And that doesn't work on macOS:
> 
> $ find /tmp/foo/ \( -path /tmp/foo/bar \) -prune -o  -type f  -print
> /tmp/foo//baz
> /tmp/foo//bar
> 
> This needs to be either "find /tmp/foo ..." (no trailing slash) or "-path /tmp/foo//bar" (double slash).  However, the latter than fails with GNU find:
> 
> $ gfind /tmp/foo/ \( -path /tmp/foo//bar \) -prune -o  -type f  -print
> /tmp/foo/baz
> /tmp/foo/bar
> 
> So probably it's better to use the former option.  That works with both both macOS find and GNU find:
> 
> $ find /tmp/foo \( -path /tmp/foo/bar \) -prune -o  -type f  -print
> /tmp/foo/baz
> $ gfind /tmp/foo \( -path /tmp/foo/bar \) -prune -o  -type f  -print
> /tmp/foo/baz
> 
> There's a comment in project--files-in-directory ";; In case DIR is a symlink."  Probably the command should use the -H option instead.

The attached patch fixes both unit tests for project.el on my macOS system.

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From 08e862623eb696a7c3df0404784abf34ed0d1ab6 Mon Sep 17 00:00:00 2001
From: Philipp Stephani <phst@google.com>
Date: Mon, 17 May 2021 21:59:57 +0200
Subject: [PATCH] Fix find invocation for macOS (Bug#48471).

* lisp/progmodes/project.el (project--files-in-directory): Instead of
appending a slash (which doesn't work well with macOS find), remove
trailing slash and pass -H instead.
---
 lisp/progmodes/project.el | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/lisp/progmodes/project.el b/lisp/progmodes/project.el
index 047f55ed1a..eab60756c8 100644
--- a/lisp/progmodes/project.el
+++ b/lisp/progmodes/project.el
@@ -297,11 +297,10 @@ project--files-in-directory
          ;; expanded and not left for the shell command
          ;; to interpret.
          (localdir (file-name-unquote (file-local-name (expand-file-name dir))))
-         (command (format "%s %s %s -type f %s -print0"
+         (command (format "%s -H %s %s -type f %s -print0"
                           find-program
                           (shell-quote-argument
-                           ;; In case DIR is a symlink.
-                           (file-name-as-directory localdir))
+                           (directory-file-name localdir)) ; Bug#48471
                           (xref--find-ignores-arguments ignores localdir)
                           (if files
                               (concat (shell-quote-argument "(")
-- 
2.30.1 (Apple Git-130)