From 078ef1845559618c485d5a5cb64522bd08945860 Mon Sep 17 00:00:00 2001
From: Stephen Sherratt <stephen@sherra.tt>
Date: Tue, 17 Sep 2024 15:26:21 +1000
Subject: [PATCH] Allow custom commands for running ocamlformat

Currently it's possible to customize the path or name of the
ocamlformat executable that gets run by the emacs ocamlformat
package. However sometimes it's desirable to run ocamlformat by
running a multi-word command, such as `opam exec ocamlformat --`. This
change adds support running coamlformat with custom multi-word
commands by allowing the `ocamlformat-command` variable to be set to a
list of strings.

Signed-off-by: Stephen Sherratt <stephen@sherra.tt>
---
 CHANGES.md           |  1 +
 emacs/ocamlformat.el | 18 ++++++++++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index 65dcb3c9ec..91a1d3e574 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -11,6 +11,7 @@ profile. This started with version 0.26.0.
 - Support OCaml 5.2 syntax (#2519, @Julow)
   This includes:
   + Local open in types.
+- Allow a custom command to be used to run ocamlformat in the emacs plugin (#2577, @gridbugs)
 
 ### Changed
 
diff --git a/emacs/ocamlformat.el b/emacs/ocamlformat.el
index e19b700179..9d0d7adb17 100644
--- a/emacs/ocamlformat.el
+++ b/emacs/ocamlformat.el
@@ -48,7 +48,9 @@
 
 (defcustom ocamlformat-command "ocamlformat"
   "The `ocamlformat' command."
-  :type 'string
+  :type '(choice
+	  (string :tag "The name of the ocamlformat executable")
+	  (repeat :tag "The prefix of the command to run to run ocamlformat" string))
   :group 'ocamlformat)
 
 (defcustom ocamlformat-enable 'enable
@@ -266,15 +268,23 @@ is nil."
            ((eq ocamlformat-file-kind 'implementation)
             (list "--impl"))
            ((eq ocamlformat-file-kind 'interface)
-            (list "--intf")))))
+            (list "--intf"))))
+	 (ocamlformat-exe
+	  (if (listp ocamlformat-command)
+	      (car ocamlformat-command)
+	    ocamlformat-command))
+	 (ocamlformat-prefix-args
+	  (if (listp ocamlformat-command)
+	      (cdr ocamlformat-command)
+	    '())))
     (unwind-protect
         (save-restriction
           (widen)
           (write-region nil nil bufferfile)
           (if (zerop
                (apply #'call-process
-                      ocamlformat-command nil (list :file errorfile) nil
-                      (append margin-args enable-args extension-args
+                      ocamlformat-exe nil (list :file errorfile) nil
+                      (append ocamlformat-prefix-args margin-args enable-args extension-args
                               (list
                                "--name" buffer-file-name
                                "--output" outputfile bufferfile))))