# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@fb.com>
# Date 1435201605 25200
# Node ID 9be1cadf7a07a0ee35b908dfc16e560673bf2ade
# Parent  3c113c097339e7c785e526eba2dbb0e02e5aa78f
next: add a --evolve option

When on a topological head, this option will trigger the evolution of a unstable
changeset that will result in a children of the current working copy parent.

This should ease stacked changesets workflow by allowing to stick to prev and
next to move through a stack of diff, evolving part of it on demand when needed.

In case of ambiguity, the command will ask the user to choose. We need a better
definition of "the stack of changesets I'm working on" to be able to seamlessly
handling branching.

diff -r 3c113c097339 -r 9be1cadf7a07 README
--- a/README	Wed Jun 24 19:42:01 2015 -0700
+++ b/README	Wed Jun 24 20:06:45 2015 -0700
@@ -68,6 +68,7 @@
           enabling
 - next/prev: requires `--merge` to move with uncommited changes
 - next: significantly reword error messages
+- next: add a --evolve flag to evolve aspiring children when on a head
 
 5.1.5 -- 2015-06-23
 
diff -r 3c113c097339 -r 9be1cadf7a07 hgext/evolve.py
--- a/hgext/evolve.py	Wed Jun 24 19:42:01 2015 -0700
+++ b/hgext/evolve.py	Wed Jun 24 20:06:45 2015 -0700
@@ -2005,10 +2005,15 @@
 @command('^next',
          [('B', 'move-bookmark', False,
              _('Move active bookmark after update')),
-          ('', 'merge', False, _('bring uncommited change along'))],
+          ('', 'merge', False, _('bring uncommited change along')),
+          ('', 'evolve', False, _('evolve the next changeset if necessary'))],
          '[-B]')
 def cmdnext(ui, repo, **opts):
-    """update to child and display summary lines"""
+    """update to next child
+
+    You can use the --evolve flag to get unstable children evolved on demand.
+
+    The summary line of the destination is displayed for clarity"""
     wkctx = repo[None]
     wparents = wkctx.parents()
     if len(wparents) != 1:
@@ -2042,13 +2047,28 @@
         ui.warn(_('explicitly update to one of them\n'))
         result = 1
     else:
-        ui.warn(_('no children\n'))
         aspchildren = _aspiringchildren(repo, [repo['.'].rev()])
-        if aspchildren:
-            msg = _('(%i unstable changesets to be evolved here, '
-                    'do you want to evolve?)\n')
-            ui.warn(msg % len(aspchildren))
-        result = 1
+        if not opts['evolve']:
+            ui.warn(_('no children\n'))
+            if aspchildren:
+                msg = _('(%i unstable changesets to be evolved here, '
+                        'do you want --evolve?)\n')
+                ui.warn(msg % len(aspchildren))
+            result = 1
+        elif 1 < len(aspchildren):
+            ui.warn("ambigious next (unstable) changeset:\n")
+            for c in aspchildren:
+                displayer.show(repo[c])
+            ui.warn(_('(run "hg evolve --rev REV" on one of them)\n'))
+            return 1
+        else:
+            cmdutil.bailifchanged(repo)
+            result = _solveone(ui, repo, repo[aspchildren[0]], False,
+                               False, lambda:None, category='unstable')
+            if not result:
+                ui.status(_('working directory now at %s\n') % repo['.'])
+            return result
+        return 1
     return result
 
 def _reachablefrombookmark(repo, revs, mark):
diff -r 3c113c097339 -r 9be1cadf7a07 tests/test-prev-next.t
--- a/tests/test-prev-next.t	Wed Jun 24 19:42:01 2015 -0700
+++ b/tests/test-prev-next.t	Wed Jun 24 20:06:45 2015 -0700
@@ -147,12 +147,12 @@
   1 new unstable changesets
   $ hg next
   no children
-  (1 unstable changesets to be evolved here, do you want to evolve?)
+  (1 unstable changesets to be evolved here, do you want --evolve?)
   [1]
-  $ hg evolve
+  $ hg next --evolve
   move:[2] added c
   atop:[3] added b (2)
-  working directory is now at e3b6d5df389b
+  working directory now at e3b6d5df389b
 
 next with ambiguity
 
@@ -179,12 +179,14 @@
   2 new unstable changesets
   $ hg next
   no children
-  (2 unstable changesets to be evolved here, do you want to evolve?)
+  (2 unstable changesets to be evolved here, do you want --evolve?)
   [1]
-  $ hg evolve
-  abort: multiple evolve candidates
-  (select one of e3b6d5df389b, 9df671ccd2c7 with --rev)
-  [255]
+  $ hg next --evolve
+  ambigious next (unstable) changeset:
+  [4] added c
+  [5] added d
+  (run "hg evolve --rev REV" on one of them)
+  [1]
   $ hg evolve -r 5
   move:[5] added d
   atop:[6] added b (3)