>>> "KK" == Konstantin Khomoutov <kos...@bswap.ru> writes:

> On Mon, Jul 10, 2023 at 06:30:04PM +0200, Uwe Brauer wrote:
>> While in mercurial «hg fetch» is equivalent to «hg pull» and «hg merge»
>> 
>> it seems that «git pull --no-ff» is not equivalent to 
>> «git fetch» and «git merge».

> This might be wrong expectations.
> I'll try to explain in simple words.


> In a VCS which uses cryptographic hashes to refer to commits, a line of
> history may be fully contained in another, say

>   A --> B --> C --> D

> fully contains

>   A --> B

> and

>   A --> B --> C

> but not, for instance,

>   A --> B --> X


> A branch fully contained in some other branch is said to be eligible for
> fast-forwarding to that containing (enclosing) branch. Why is that?
> Because if we, say, have that A --> B line of commits on some branch,
> and want that branch to now become A --> B --> C --> D, there's no real need
> to _actually merge_ that C --> D bit: we can instead just update the branch to
> point directly at D, with not merge commit involved.


> Git defaults to this fast-forward behavior in every place merging is involved,
> and `git pull` is one of such places. 

So far I had assumed.

> Going back to our example, if you locally have your "master" to
> contain A --> B, and "master" in the remote repo contains A --> B -->
> C --> D, pulling from that branch will by default to a fast-forward
> merge. 


> The "--no-ff" command-line option for `git pull` is actually
> passed by that command to `git merge` it eventually calls, and forces
> the latter to not do a fast-forward and instead record a true merge,
> resulting in a merge commit recorded, which has two parents: B and D.

But that is where my confusing starts I used the "--no-ff" option and
nevertheless git performed (at least the graphs looks to me like that) 
a fast forward.


Is there no way to configure pull that it produces the same graph, as 
git fetch+merge?

Mercurial seems to do that and I will ask some mercurial guru how it
does it.

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