How do I check for potential merge/rebase conflicts in Mercurial?

Question

Is there a simple way to check if a merge/rebase will yield file conflicts, without actually performing the merge/rebase?

I want to be able to decide whether to:

Answer 1

There is no reason to use hg merge if the changes overlap and hg rebase otherwise since hg rebase make a merge internally and will let you resolve it using the same tools as hg merge.

As for testing if a merge or rebase will cause conflicts, then you can use

$ hg merge --tool internal:merge

in Mercurial 1.7 to override your normal merge tool configuration. (The --tool internal:merge part is new, use --config ui.merge=internal:merge in earlier versions of Mercurial.)

Following the merge,

$ hg resolve --list

will tell you the results and you will get back to where you started with

$ hg update --clean .