How do I get a squashed diff for review

Hi,

I'm wondering if there is an easy way to get a squashed diff of the changes done on the feature branch for review. In the simple cases (where feature branch is linear) there is an absolutely fantastic way to get a patch for review: git diff master...feature

However if the feature branch happened to be long-lived and had mainline merged into it it's not going to work -- the resulting diff would contain changes from the merge. The way we are doing things now is to merge master into it once more and then diff, however this is somewhat cumbersome. Is there easier way to do it?

And while we are on the topic -- is there a tool for git similar to "bzr qdiff"? It's a simple graphical diff viewer with 2 nice features -- it shows complete diff (of multiple files) in a single window and has a checkbox to switch between diff-only & full-text modes. I have seen difftool, but it seems to work on per-file basis, and something like "vi <(git diff ...)" lacks the easy way to switch into full-text mode.

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Best regards,
  Alexander.