master 1eae0e7edf4: Teach ffap to look for relative file names under project-root

[Dmitry Gutov]

branch: master
commit 1eae0e7edf485bdaa9fb76b905275cf08a1910e2
Author: Spencer Baugh <sbaugh@janestreet.com>
Commit: Dmitry Gutov <dmitry@gutov.dev>

    Teach ffap to look for relative file names under project-root
    
    Now file-name-at-point-functions, which runs
    ffap-guess-file-name-at-point, will pick up on a file name at point if
    that file name is a relative file name which exists when looked up
    from the root of the project.
    
    For example, in test/lisp/progmodes/eglot-tests.el there is the string
    lisp/progmodes/eglot.el; if you put point on that and C-x C-f,
    lisp/progmodes/eglot.el under the root of the Emacs repo will now be
    part of future history.
    
    * lisp/ffap.el (ffap-alist): Add entry for ffap-in-project.
    (ffap-in-project): Add. (bug#66668)
---
 lisp/ffap.el | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lisp/ffap.el b/lisp/ffap.el
index 942e218bf23..530e3da182e 100644
--- a/lisp/ffap.el
+++ b/lisp/ffap.el
@@ -730,6 +730,7 @@ This uses `ffap-file-exists-string', which may try adding 
suffixes from
 (defvar ffap-alist
   '(
     ("" . ffap-completable)            ; completion, slow on some systems
+    ("" . ffap-in-project)             ; maybe in the root of the project
     ("\\.info\\'" . ffap-info)         ; gzip.info
     ("\\`info/" . ffap-info-2)         ; info/emacs
     ("\\`[-[:lower:]]+\\'" . ffap-info-3) ; (emacs)Top [only in the 
parentheses]
@@ -793,6 +794,11 @@ to extract substrings.")
         (cmp (file-name-completion (file-name-nondirectory name) dir)))
     (and cmp (concat dir cmp))))
 
+(declare-function project-root "project" (project))
+(defun ffap-in-project (name)
+  (when-let (project (project-current))
+    (file-name-concat (project-root project) name)))
+
 (defun ffap-home (name) (ffap-locate-file name t '("~")))
 
 (defun ffap-info (name)