Improve documentation for include_file_mtime

diff --git a/MANUAL.txt b/MANUAL.txt
index 4b0cfb22af1ba1a0ce918fc89fb25c49418898a7..4be33aedc88cd99e57e2bf049385c23a4faa6f7e 100644 (file)
--- a/MANUAL.txt
+++ b/MANUAL.txt
@@ -425,7 +425,8 @@ WRAPPERS>>.
 *file_macro*::
     Ignore *\_\_FILE__* being present in the source.
 *include_file_mtime*::
-    Don't check the modification time of include files in the direct mode.
+    By default, ccache will not cache a file if it includes a header whose
+    mtime is too new.  This option disables that check.
 *time_macros*::
     Ignore *\_\_DATE\__* and *\_\_TIME__* being present in the source code.
 --