.dir-locals: Streamline Geiser configuration.

Geiser now has support locating the project root and adding it to the load
path without external help; leverage it.

* .dir-locals.el [nil]: Remove obsolete Geiser configuration.  Set the
geiser-repl-per-project-p variable to t.
* doc/contributing.texi (The Perfect Setup): No longer mention explicitly
setting the geiser-guile-load-path; instead mention the effect of the
.dir-locals.el file.

Reported-by: Wolf <wolf@wolfsden.cz>

2 files changed, 5 insertions, 30 deletions

diff --git a/.dir-locals.el b/.dir-locals.el
index d79b5c9d7e..36714c1aa4 100644
--- a/.dir-locals.el
+++ b/.dir-locals.el
@@ -32,27 +32,7 @@
      ;; Geiser
      ;; This allows automatically setting the `geiser-guile-load-path'
      ;; variable when using various Guix checkouts (e.g., via git worktrees).
-     (eval . (let ((root-dir-unexpanded (locate-dominating-file
-                                         default-directory ".dir-locals.el")))
-               ;; While Guix should in theory always have a .dir-locals.el
-               ;; (we are reading this file, after all) there seems to be a
-               ;; strange problem where this code "escapes" to some other buffers,
-               ;; at least vc-mode.  See:
-               ;;   https://lists.gnu.org/archive/html/guix-devel/2020-11/msg00296.html
-               ;; Upstream report: <https://bugs.gnu.org/44698>
-               ;; Hence the following "when", which might otherwise be unnecessary;
-               ;; it prevents causing an error when root-dir-unexpanded is nil.
-               (when root-dir-unexpanded
-                 (let* ((root-dir (file-local-name (expand-file-name root-dir-unexpanded)))
-                        ;; Workaround for bug https://issues.guix.gnu.org/43818.
-                        (root-dir* (directory-file-name root-dir)))
-
-                   (unless (boundp 'geiser-guile-load-path)
-                     (defvar geiser-guile-load-path '()))
-                   (make-local-variable 'geiser-guile-load-path)
-                   (require 'cl-lib)
-                   (cl-pushnew root-dir* geiser-guile-load-path
-                               :test #'string-equal)))))))
+     (geiser-repl-per-project-p . t)))
 
  (c-mode          . ((c-file-style . "gnu")))
  (scheme-mode
diff --git a/doc/contributing.texi b/doc/contributing.texi
index fa9238fde8..a0da871f1a 100644
--- a/doc/contributing.texi
+++ b/doc/contributing.texi
@@ -300,15 +300,10 @@ Geiser allows for interactive and incremental development from within
 Emacs: code compilation and evaluation from within buffers, access to
 on-line documentation (docstrings), context-sensitive completion,
 @kbd{M-.} to jump to an object definition, a REPL to try out your code,
-and more (@pxref{Introduction,,, geiser, Geiser User Manual}).  For
-convenient Guix development, make sure to augment Guile’s load path so
-that it finds source files from your checkout:
-
-@lisp
-;; @r{Assuming the Guix checkout is in ~/src/guix.}
-(with-eval-after-load 'geiser-guile
-  (add-to-list 'geiser-guile-load-path "~/src/guix"))
-@end lisp
+and more (@pxref{Introduction,,, geiser, Geiser User Manual}).  If you
+allow Emacs to load the @file{.dir-locals.el} file at the root of the
+project checkout, it will cause Geiser to automatically add the local
+Guix sources to the Guile load path.
 
 To actually edit the code, Emacs already has a neat Scheme mode.  But in
 addition to that, you must not miss