help: add topic about evolution, based on text from evolve extension
I've taken the text produced by `hg help evolution` when the evolve
extension is enabled and made that available by the same command with
just hg core. Changes I've made:
* Added "(EXPERIMENTAL)" to the title. (That doesn't hide the topic
from `hg help`, though.)
* Replaced old-style `experimental.evolution=<names>` config by
new-style `experimental.evolution.<name>=true`.
* Replaces a "obsolete markers" by "obsolescence markers".
* Removed most content from "Current feature status".
When the evolve extension is enabled, its help text takes precedence.
Differential Revision: https://phab.mercurial-scm.org/D10516
--- a/mercurial/help.py Thu Feb 11 15:02:57 2021 -0800
+++ b/mercurial/help.py Tue Apr 27 14:59:45 2021 -0700
@@ -540,6 +540,12 @@
TOPIC_CATEGORY_CONCEPTS,
),
(
+ [b"evolution"],
+ _(b"Safely rewriting history (EXPERIMENTAL)"),
+ loaddoc(b'evolution'),
+ TOPIC_CATEGORY_CONCEPTS,
+ ),
+ (
[b'scripting'],
_(b'Using Mercurial from scripts and automation'),
loaddoc(b'scripting'),
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/helptext/evolution.txt Tue Apr 27 14:59:45 2021 -0700
@@ -0,0 +1,56 @@
+Obsolescence markers make it possible to mark changesets that have been
+deleted or superseded in a new version of the changeset.
+
+Unlike the previous way of handling such changes, by stripping the old
+changesets from the repository, obsolescence markers can be propagated
+between repositories. This allows for a safe and simple way of exchanging
+mutable history and altering it after the fact. Changeset phases are
+respected, such that only draft and secret changesets can be altered (see
+:hg:`help phases` for details).
+
+Obsolescence is tracked using "obsolescence markers", a piece of metadata
+tracking which changesets have been made obsolete, potential successors for
+a given changeset, the moment the changeset was marked as obsolete, and the
+user who performed the rewriting operation. The markers are stored
+separately from standard changeset data can be exchanged without any of the
+precursor changesets, preventing unnecessary exchange of obsolescence data.
+
+The complete set of obsolescence markers describes a history of changeset
+modifications that is orthogonal to the repository history of file
+modifications. This changeset history allows for detection and automatic
+resolution of edge cases arising from multiple users rewriting the same part
+of history concurrently.
+
+Current feature status
+======================
+
+This feature is still in development.
+
+Instability
+===========
+
+Rewriting changesets might introduce instability.
+
+There are two main kinds of instability: orphaning and diverging.
+
+Orphans are changesets left behind when their ancestors are rewritten.
+Divergence has two variants:
+
+* Content-divergence occurs when independent rewrites of the same changesets
+ lead to different results.
+
+* Phase-divergence occurs when the old (obsolete) version of a changeset
+ becomes public.
+
+It is possible to prevent local creation of orphans by using the following config::
+
+ [experimental]
+ evolution.createmarkers = true
+ evolution.exchange = true
+
+You can also enable that option explicitly::
+
+ [experimental]
+ evolution.createmarkers = true
+ evolution.exchange = true
+ evolution.allowunstable = true
--- a/tests/test-globalopts.t Thu Feb 11 15:02:57 2021 -0800
+++ b/tests/test-globalopts.t Tue Apr 27 14:59:45 2021 -0700
@@ -419,6 +419,7 @@
Concepts:
bundlespec Bundle File Formats
+ evolution Safely rewriting history (EXPERIMENTAL)
glossary Glossary
phases Working with Phases
subrepos Subrepositories
@@ -552,6 +553,7 @@
Concepts:
bundlespec Bundle File Formats
+ evolution Safely rewriting history (EXPERIMENTAL)
glossary Glossary
phases Working with Phases
subrepos Subrepositories
--- a/tests/test-help-hide.t Thu Feb 11 15:02:57 2021 -0800
+++ b/tests/test-help-hide.t Tue Apr 27 14:59:45 2021 -0700
@@ -117,6 +117,7 @@
Concepts:
bundlespec Bundle File Formats
+ evolution Safely rewriting history (EXPERIMENTAL)
glossary Glossary
phases Working with Phases
subrepos Subrepositories
@@ -254,6 +255,7 @@
Concepts:
bundlespec Bundle File Formats
+ evolution Safely rewriting history (EXPERIMENTAL)
glossary Glossary
phases Working with Phases
subrepos Subrepositories
--- a/tests/test-help.t Thu Feb 11 15:02:57 2021 -0800
+++ b/tests/test-help.t Tue Apr 27 14:59:45 2021 -0700
@@ -169,6 +169,7 @@
Concepts:
bundlespec Bundle File Formats
+ evolution Safely rewriting history (EXPERIMENTAL)
glossary Glossary
phases Working with Phases
subrepos Subrepositories
@@ -298,6 +299,7 @@
Concepts:
bundlespec Bundle File Formats
+ evolution Safely rewriting history (EXPERIMENTAL)
glossary Glossary
phases Working with Phases
subrepos Subrepositories
@@ -2274,6 +2276,13 @@
Environment Variables
</td></tr>
<tr><td>
+ <a href="/help/evolution">
+ evolution
+ </a>
+ </td><td>
+ Safely rewriting history (EXPERIMENTAL)
+ </td></tr>
+ <tr><td>
<a href="/help/extensions">
extensions
</a>
--- a/tests/test-hgweb-json.t Thu Feb 11 15:02:57 2021 -0800
+++ b/tests/test-hgweb-json.t Tue Apr 27 14:59:45 2021 -0700
@@ -2272,6 +2272,10 @@
"topic": "environment"
},
{
+ "summary": "Safely rewriting history (EXPERIMENTAL)",
+ "topic": "evolution"
+ },
+ {
"summary": "Using Additional Features",
"topic": "extensions"
},