diff mercurial/merge.py @ 31168:41a9edc5d00f

update: allow setting default update check to "noconflict"

The new value allows update (linear or not) as long as they don't
result in file merges.

I'm hoping that this value can some day become the default.

--- a/mercurial/merge.py	Mon Feb 13 16:03:05 2017 -0800
+++ b/mercurial/merge.py	Mon Feb 13 00:05:55 2017 -0800
@@ -1465,21 +1465,27 @@
     The table below shows all the behaviors of the update command
     given the -c and -C or no options, whether the working directory
     is dirty, whether a revision is specified, and the relationship of
-    the parent rev to the target rev (linear or not). Match from top first.
+    the parent rev to the target rev (linear or not). Match from top first. The
+    -n option doesn't exist on the command line, but represents the
+    experimental.updatecheck=noconflict option.
 
     This logic is tested by test-update-branches.t.
 
-    -c  -C  -m  dirty  rev  linear  |  result
-     y   y   *    *     *     *     |    (1)
-     y   *   y    *     *     *     |    (1)
-     *   y   y    *     *     *     |    (1)
-     *   *   *    *     n     n     |     x
-     *   *   *    n     *     *     |    ok
-     n   n   n    y     *     y     |   merge
-     n   n   n    y     y     n     |    (2)
-     n   n   y    y     *     *     |   merge
-     n   y   n    y     *     *     |  discard
-     y   n   n    y     *     *     |    (3)
+    -c  -C  -n  -m  dirty  rev  linear  |  result
+     y   y   *   *    *     *     *     |    (1)
+     y   *   y   *    *     *     *     |    (1)
+     y   *   *   y    *     *     *     |    (1)
+     *   y   y   *    *     *     *     |    (1)
+     *   y   *   y    *     *     *     |    (1)
+     *   *   y   y    *     *     *     |    (1)
+     *   *   *   *    *     n     n     |     x
+     *   *   *   *    n     *     *     |    ok
+     n   n   n   n    y     *     y     |   merge
+     n   n   n   n    y     y     n     |    (2)
+     n   n   n   y    y     *     *     |   merge
+     n   n   y   n    y     *     *     |  merge if no conflict
+     n   y   n   n    y     *     *     |  discard
+     y   n   n   n    y     *     *     |    (3)
 
     x = can't happen
     * = don't-care
@@ -1499,7 +1505,7 @@
         # updatecheck='abort' to better suppport some of these callers.
         if updatecheck is None:
             updatecheck = 'linear'
-        assert updatecheck in ('none', 'linear')
+        assert updatecheck in ('none', 'linear', 'noconflict')
     # If we're doing a partial update, we need to skip updating
     # the dirstate, so make a note of any partial-ness to the
     # update here.
@@ -1593,6 +1599,13 @@
             repo, wc, p2, pas, branchmerge, force, mergeancestor,
             followcopies, matcher=matcher, mergeforce=mergeforce)
 
+        if updatecheck == 'noconflict':
+            for f, (m, args, msg) in actionbyfile.iteritems():
+                if m not in ('g', 'k', 'r'):
+                    msg = _("uncommitted changes")
+                    hint = _("commit or update --merge to allow merge")
+                    raise error.Abort(msg, hint=hint)
+
         # Prompt and create actions. Most of this is in the resolve phase
         # already, but we can't handle .hgsubstate in filemerge or
         # subrepo.submerge yet so we have to keep prompting for it.