# HG changeset patch
# User Bruno Haible <bruno@clisp.org>
# Date 1055416334 0
# Node ID ca90cd92b340ba0c7e17743aa5e1124ab5ca6ae2
# Parent  cbadaf82e39bb7dd3eac37aa99af650181422b0a
Add a note about empty files.

diff --git a/README b/README
--- a/README
+++ b/README
@@ -64,6 +64,12 @@
 * Try to prevent that the files are built if they aren't needed on a
   platform.  Valid excuses to this rule include ELIDE constructs that
   lead to an empty .o file (see getopt module).
+* If you have a .c file that leads to an empty .o file on some platforms
+  (through some big #if around all the code), still make sure that after
+  preprocessing the compilation unit is not empty. This is usually fulfilled
+  if you #include <stdio.h> or #include <sys/types.h> before the big #if;
+  otherwise you need to add a #else branch containing "typedef int dummy;"
+  or "extern int dummy;".
 
 High Quality
 ============