diff mercurial/patch.py @ 9725:3f522d2fa633

diff: add --inverse option

Most of the time, one can reverse a diff by swapping the revisions passed with
-r but it happens that if you use the global -R, and diff against the tip of
the current repo, you can't swap the revisions. One use-case for that is
reviewing changes from a bundle before unbundling. One could also pipe the
output of `hg diff` to a command line filter that reverses the diff, but that
would remove the benefit from color diffs. Therefore, having an option in
`hg diff` to reverse a diff is a good thing.

The option flag selection was tricky. GNU patch uses -R/--reverse but -R is
already used as a global option and --reverse would make --rev ambiguous.

--- a/mercurial/patch.py	Thu Nov 05 15:06:35 2009 +0100
+++ b/mercurial/patch.py	Thu Nov 05 15:18:56 2009 +0100
@@ -1216,7 +1216,7 @@
     if opts is None:
         opts = mdiff.defaultopts
 
-    if not node1:
+    if not node1 and not node2:
         node1 = repo.dirstate.parents()[0]
 
     def lrugetfilectx():