[PATCH 0 of 1] merge: add --no-fast-forward to suppress fast-forward merge
adrian at cadifra.com
Sun Mar 6 05:37:47 CST 2011
On 2011-03-06 12:02, Didly (aka Angel Ezquerra :-) wrote:
> Actually this is the first I've heard of it and I don't really know what
> it means. Is it related to merging with a descendant?
> Anyway, I guess it does confuse at least some existing users :-)
Consider the following DAG (DAG=directed acyclic graph; time increases
from left to right):
\ Figure 1
If you update to d1, merge with s2, and commit, mercurial will notice
that there were no changes on the default branch and will just create a
new commit with the branch name "default".
The result will be a new changeset d2 on default, even though you said
"hg merge s2":
default --o-----o o
\ / Figure 2a
Note that the new changeset d2 has a single parent s2. No merge changeset!
You could do the same with 'hg branch --force default', followed by commit.
So, mercurial is just doing a "fast-forward" on the stable branch,
instead of really doing:
\ / Figure 2b
If mercurial would really do a d2' merge changeset, that changeset would
contain no file changes at all.
Similarly, d2 in figure 2a does not contain any file changes at all.
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