Fix Bug#33618; define search path variables for grep, byte-compile

* etc/NEWS: Mention new variables.

* lisp/emacs-lisp/bytecomp.el (emacs-lisp-compilation-search-path): New.

* lisp/progmodes/grep.el (grep-search-path): New.

3 files changed, 29 insertions, 2 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 788be7060af..721ebb2dedd 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -325,8 +325,17 @@ and directory-local variables.
 longer.
 
 ---
-** next-error-verbose controls when `next-error' outputs a message
-   about the error locus.
+** New variable next-error-verbose controls when `next-error' outputs
+   a message about the error locus.
+
+---
+** New variable grep-search-path defines the directories searched for
+   grep hits (this used to be controlled by compilation-search-path).
+
+---
+** New variable emacs-lisp-compilation-search-path defines the
+   directories searched for byte-compiler error messages (this used to
+   be controlled by compilation-search-path).
 
 
 * Editing Changes in Emacs 27.1
diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index 4c61e1a4471..e76baf5ed0d 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -1022,6 +1022,15 @@ If STR is something like \"Buffer foo.el\", return #<buffer foo.el>
   "The value for `compilation-parse-errors-filename-function' for when
 we go into emacs-lisp-compilation-mode.")
 
+(defcustom emacs-lisp-compilation-search-path '(nil)
+  "Search path for byte-compile error messages.
+Elements should be directory names, not file names of directories.
+The value nil as an element means to try the default directory."
+  :group 'bytecomp
+  :version "27.1"
+  :type '(repeat (choice (const :tag "Default" nil)
+			 (string :tag "Directory"))))
+
 (define-compilation-mode emacs-lisp-compilation-mode "elisp-compile"
   "The variant of `compilation-mode' used for emacs-lisp error buffers")
 
diff --git a/lisp/progmodes/grep.el b/lisp/progmodes/grep.el
index 8c7a58fd8bd..85f9078d46d 100644
--- a/lisp/progmodes/grep.el
+++ b/lisp/progmodes/grep.el
@@ -441,6 +441,15 @@ abbreviated part can also be toggled with
   :version "27.1"
   :group 'grep)
 
+(defcustom grep-search-path '(nil)
+  "Search path for grep results.
+Elements should be directory names, not file names of directories.
+The value nil as an element means to try the default directory."
+  :group 'grep
+  :version "27.1"
+  :type '(repeat (choice (const :tag "Default" nil)
+			 (string :tag "Directory"))))
+
 (defvar grep-find-abbreviate-properties
   (let ((ellipsis (if (char-displayable-p ?…) "[…]" "[...]"))
         (map (make-sparse-keymap)))