How to display outgoing diff without merges? - mercurial

Question

When using mercurial, when working on a large change, I will do several commits (as safe points, or share my progress with coworkers).
Whe I am done, I want to push my changes into the main repository. Before I do that, though, I will want to do a "hg pull -u && hg merge"to get changes that occured since my last pull, and review my changes.
Because I have several changesets, running hg diff on each of those is not a good solution.
I tried running hg diff -c"outgoing() and not merge()" to only show the diff for my outgoing changesets (without merge ones, as this tends to only add noise which I want to avoid).
However, it is still not ok for me, as mercurial seems to skip some information, and I do not understand on what basis. Please refer to the scenario below:
full scenario:
# clean working directory
rm -fr base clone
#prepare reference repo
mkdir base; cd base
hg init
touch 1.txt
echo " 1\n2" >>1.txt
hg add 1.txt
touch 2.txt
hg add 2.txt
hg commit -m"initial commit"
cd ..
hg clone base clone
cd base
#update ref repo.
echo "foo" >> 1.txt
hg commit -m"update file on remote repository"
#make changes locally
cd ../clone
echo "foo" >> 2.txt
hg commit -m "update initial file"
#now we are ready to push
hg pull -u && hg merge
hg commit -m"merge"
#actually...
sed -i -e 's/foo/bar/' 2.txt
hg commit -m"changed my mind"
hg out
changeset: 1:fce14ac089b2
date: Thu Nov 14 11:17:08 2013 +0100
summary: update initial file
changeset: 3:1967c50242c0
parent: 1:fce14ac089b2
parent: 2:2cdaf75afc6d
date: Thu Nov 14 11:17:10 2013 +0100
summary: merge
changeset: 4:120a0b8a0ede
tag: tip
date: Thu Nov 14 11:18:54 2013 +0100
summary: changed my mind
#try to display my changes
hg diff -c"outgoing() and not merge()"
--- a/2.txt Thu Nov 14 11:17:10 2013 +0100
+++ b/2.txt Thu Nov 14 11:18:54 2013 +0100
## -1,1 +1,1 ##
-foo
+bar
#only one change here!
#but
hg log -r"outgoing() and not merge()"
changeset: 1:fce14ac089b2
date: Thu Nov 14 11:17:08 2013 +0100
summary: update initial file
changeset: 4:120a0b8a0ede
tag: tip
date: Thu Nov 14 11:18:54 2013 +0100
summary: changed my mind
#is ok
So, could anyone please explain to me why mercurial skips changeset fce14ac089b2 entirely? What I expect is a consolidated output, i.e something like:
--- a/2.txt
+++ b/2.txt
## -1,1 +1,1 ##
+bar
Thanks a lot in advance.

Answer 1

I think the problem is a misunderstanding of what hg diff -c aka hg diff --change does. It takes a single revision id and shows you the change made by that one revision relative to its left parent.
You're calling:
hg diff -c"outgoing() and not merge()"
which yields multiple revisions (it's a revision set), but only one of them is being used. You're essentially seeing the output of:
hg diff --change 120a0b8a0ede
If what you're trying to do is see all of your outgoing changes lumped together in one diff you don't want --change/-c.
If you think about it the revset outgoing() could contain many changeset from many branches so smooshing them all into one diff isn't necessarily possible at all.
If the view you're trying to get is "how does the most recent head on branch default locally compare to the most recent head on default remotely" you need to know the node id of the most recent head on default, and then locally you'd just run:
hg diff node_id_of_most_recent_head_on_default_at_remote_site

Answer 2

This isn't guaranteed, as I expect that there's some way to have a change graph where the last public ancestor isn't the change-set you're after, but...
> hg diff -r "last(ancestors(.) and public())"
diff -r 5579be654db4 2.txt
--- a/2.txt Sat Nov 16 11:03:06 2013 +0000
+++ b/2.txt Sat Nov 16 11:29:34 2013 +0000
## -0,0 +1,1 ##
+bar