diff relnotes/next @ 44396:acbfa31cfaf2

debugmergestate: make templated

Our IntelliJ team wants to be able to read the merge state in order to
help the user resolve merge conflicts. They had so far been reading
file contents from p1() and p2() and their merge base. That is not
ideal for several reasons (merge base is not necessarily the "graft
base", renames are not handled, commands like `hg update -m` is not
handled). It will get especially bad as of my D7827. This patch makes
the output s a templated. I haven't bothered to make it complete
(e.g. merge driver states are not handled), but it's probably good
enough as a start.

I've done a web search for "debugmergestate" and I can't find any
indication that any tools currently rely on its output. If it turns
out that we get bug reports for it once this is released, I won't
object to backing this patch out on the stable branch (and then
perhaps replace it by a separate command, or put it behind a new
flag).

The changes in test-backout.t are interesting, in particular this:

```
  -    other path: foo (node not stored in v1 format)
  +    other path:  (node foo)
```

I wonder if that means that we actually read v1 format
incorrectly. That seems to be an old format that was switched away
from in 2014, so it doesn't matter now anyway.

Differential Revision: https://phab.mercurial-scm.org/D8120

--- a/relnotes/next	Thu Feb 13 21:55:38 2020 -0800
+++ b/relnotes/next	Thu Feb 13 21:14:20 2020 -0800
@@ -23,6 +23,10 @@
    Will use `zstd` compression for new repositories is available, and will
    simply fall back to `zlib` if not.
 
+ * `hg debugmergestate` output is now templated, which may be useful
+   e.g. for IDEs that want to help the user resolve merge conflicts.
+
+
 == New Experimental Features ==
 
  * `hg copy` now supports a `--at-rev` argument to mark files as
@@ -49,6 +53,10 @@
  * `hg recover` does not verify the validity of the whole repository
    anymore. You can pass `--verify` or call `hg verify` if necessary.
 
+ * `hg debugmergestate` output format changed. Let us know if that is
+   causing you problems and we'll roll it back.
+
+
 == Internal API Changes ==
 
  * The deprecated `ui.progress()` has now been deleted. Please use