Replacing a (sym-) link by its target

David A. Cobb writes:
 > I've been using lndir with some success during make's -- leaving the 
 > source tree alone and read-only, building in the link tree. 
 > 
 > When it comes time to change something, it seems the best way to do it 
 > is make the working copy in the build tree.
 > If I just read the link, I get the original file -- but I also try to 
 > replace the (read-only) original file. 
 > 
 > The sequence of operations otta be something like
 > (if (and (visited-file-is-a-link) (target-is-read-only))
 >     ((rename-the-link) ;; to get it out of the way
 >     (write-the-buffer)
 >     (delete-the-renamed-link))
 >     ; otherwise
 >     (write-the-buffer))
 > 
 > Comment?

Setting file-precious-flag gets you effect of replacing the link
with a regular file.  But what you describe woudl be a useful
option for peopel who spend a lot of time working on RO mounted
source trees.