oddities with fgrep

$ fgrep -w -r CS drm
...
drm/include/drm/drm_mode.h:#define DRM_MODE_FLAG_NCSYNC (1<<8)
$ fgrep -w -r CSY drm
...
drm/include/drm/drm_mode.h:#define DRM_MODE_FLAG_NCSYNC (1<<8)
$ fgrep -w -r CSYN drm
<nothing> (exit 1)
$ fgrep -w -r NCS drm
<nothing> (exit 1)
$ fgrep -w CS drm/include/drm/drm_mode.h
<nothing> (exit 1)

So looks like a potential bug in some optimization.
-w works correctly without -r.  With -r it works correctly for some substrings,
but not for others.

-- 
Andriy Gapon