Improve doc strings for some -search-path variables

* lisp/emacs-lisp/bytecomp.el (emacs-lisp-compilation-search-path):
Improve doc string.

* lisp/progmodes/compile.el (compilation-search-path): Improve doc
string.

* lisp/progmodes/grep.el (grep-search-path): Improve doc string.

3 files changed, 11 insertions, 8 deletions

diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index 431525431a4..125344b779b 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -1037,9 +1037,10 @@ If STR is something like \"Buffer foo.el\", return #<buffer foo.el>
 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."
+  "Directories to search for files named in byte-compile error messages.
+Value should be a list of directory names, not file names of
+directories.  The value nil as an element means the byte-compile
+message buffer `default-directory'."
   :version "27.1"
   :type '(repeat (choice (const :tag "Default" nil)
                          (string :tag "Directory"))))
diff --git a/lisp/progmodes/compile.el b/lisp/progmodes/compile.el
index 4b2fc516c3d..7537525a063 100644
--- a/lisp/progmodes/compile.el
+++ b/lisp/progmodes/compile.el
@@ -677,8 +677,9 @@ of `my-compilation-root' here."
 ;;;###autoload
 (defcustom compilation-search-path '(nil)
   "List of directories to search for source files named in error messages.
-Elements should be directory names, not file names of directories.
-The value nil as an element means to try the default directory."
+Elements should be directory names, not file names of
+directories.  The value nil as an element means the error
+message buffer `default-directory'."
   :type '(repeat (choice (const :tag "Default" nil)
                          (string :tag "Directory"))))
 
diff --git a/lisp/progmodes/grep.el b/lisp/progmodes/grep.el
index 67222f78627..306ae8fd50f 100644
--- a/lisp/progmodes/grep.el
+++ b/lisp/progmodes/grep.el
@@ -442,9 +442,10 @@ abbreviated part can also be toggled with
   :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."
+  "List of directories to search for files named in grep messages.
+Elements should be directory names, not file names of
+directories.  The value nil as an element means the grep messages
+buffer `default-directory'."
   :group 'grep
   :version "27.1"
   :type '(repeat (choice (const :tag "Default" nil)