[PATCH 3 of 9] update: add error message for dirty non-linear update with no rev

[Martin Geisler]

Siddharth Agarwal <sid0 at fb.com> writes:

> # HG changeset patch
> # User Siddharth Agarwal <sid0 at fb.com>
> # Date 1379992050 25200
> #      Mon Sep 23 20:07:30 2013 -0700
> # Node ID 3c9d933940fabae7052a1bdad0eb9b47e61fb455
> # Parent  eddb6f0b067c90910adb968dfb7eb798961e0ab2
> update: add error message for dirty non-linear update with no rev
>
> Previously, the error message for a dirty non-linear update was the
> same (and relatively unhelpful) whether or not a rev was specified.
> This patch and an upcoming one will introduce separate, more helpful
> hints.
>
> diff --git a/mercurial/merge.py b/mercurial/merge.py
> --- a/mercurial/merge.py
> +++ b/mercurial/merge.py
> @@ -656,19 +656,21 @@
>      -c  -C  dirty  rev  |  linear   same  cross
>       n   n    n     n   |    ok     (1)     x
>       n   n    n     y   |    ok     ok     ok
> -     n   n    y     *   |   merge   (2)    (2)
> +     n   n    y     n   |   merge   (2)    (2)
> +     n   n    y     y   |   merge   (3)    (3)
>       n   y    *     *   |    ---  discard  ---
> -     y   n    y     *   |    ---    (3)    ---
> +     y   n    y     *   |    ---    (4)    ---
>       y   n    n     *   |    ---    ok     ---
> -     y   y    *     *   |    ---    (4)    ---
> +     y   y    *     *   |    ---    (5)    ---
>  
>      x = can't happen
>      * = don't-care
>      1 = abort: not a linear update (merge or update --check to force update)
>      2 = abort: crosses branches (use 'hg merge' to merge or
>                   use 'hg update -C' to discard changes)
> -    3 = abort: uncommitted local changes
> -    4 = incompatible options (checked in commands.py)
> +    3 = abort: uncommitted changes (commit or update --clean to discard changes)

I know you didn't introduce this behaviour originally and that you're
just making the existing message more clear. But is this not bad advice?

I almost *never* want to use 'hg update --clean'. It's a bad option
since it throws away data. Suggesting that people use 'hg revert' would
be better IMHO since that gives them backup files by default.

Further: if I say 'hg update X', and Mercurial aborts, then I must go
through the 'hg update "ancestor(., X)"; hg update X' dance. What I
really need in that situation is for Mercurial to help me move (merge)
them into the target revision. It is extremely rare that I want to throw
away my changes with 'hg update --clean'.

-- 
Martin Geisler