+(defcustom compilation-save-buffers-predicate nil
+ "The second argument (PRED) passed to `save-some-buffers' before compiling.
+E.g., one can set this to
+ (lambda ()
+ (string-prefix-p my-compilation-root (file-truename (buffer-file-name))))
+to limit saving to files located under `my-compilation-root'.
+Note, that, in general, `compilation-directory' cannot be used instead
+of `my-compilation-root' here."
+ :type '(choice
+ (const :tag "Default (save all file-visiting buffers)" nil)
+ (const :tag "Save all buffers" t)
+ function)
+ :group 'compilation
+ :version "24.1")
+