Add recommendation to not use "ccache distcc compiler" as the compiler

diff --git a/manual.txt b/manual.txt
index 52cd144a69609d68c8891964318afb6d10d0a7e1..1af3ce54ac1d7265f72f5374f185c9bdeecd131a 100644 (file)
--- a/manual.txt
+++ b/manual.txt
@@ -536,6 +536,12 @@ The recommended way of combining distcc and ccache is by using the
 *CCACHE_PREFIX* to *distcc* and ccache will prefix the command line used with
 the compiler with the command ``distcc''.
 
+It is not recommended to use the form *ccache distcc compiler args* as the
+compilation command, because ccache will in that case hash the mtime of distcc
+instead of the compiler (see the *CCACHE_COMPILERCHECK* option), which means
+that compiler upgrades will not be detected properly and that the cached
+results will not be shared between compilations with and without distcc.
+
 
 BUGS
 ----