--- a/mercurial/commands.py	Mon Mar 20 11:38:37 2017 +0900
+++ b/mercurial/commands.py	Tue Mar 14 17:43:18 2017 -0700
@@ -5349,6 +5349,11 @@
     if rev and node:
         raise error.Abort(_("please specify just one revision"))
 
+    if ui.configbool('commands', 'update.requiredest', False):
+        if not node and not rev and not date:
+            raise error.Abort(_('you must specify a destination'),
+                              hint=_('for example: hg update ".::"'))
+
     if rev is None or rev == '':
         rev = node
 

--- a/mercurial/help/config.txt	Mon Mar 20 11:38:37 2017 +0900
+++ b/mercurial/help/config.txt	Tue Mar 14 17:43:18 2017 -0700
@@ -414,6 +414,15 @@
     a different color mode than the pager (activated via the "pager"
     extension).
 
+``commands``
+----------
+
+``update.requiredest``
+    Require that the user pass a destination when running ``hg update``.
+    For example, ``hg update .::`` will be allowed, but a plain ``hg update``
+    will be disallowed.
+    (default: False)
+
 ``committemplate``
 ------------------
 

--- a/tests/test-update-names.t	Mon Mar 20 11:38:37 2017 +0900
+++ b/tests/test-update-names.t	Tue Mar 14 17:43:18 2017 -0700
@@ -88,3 +88,19 @@
   (consider changing to repo root: $TESTTMP/r1/r4)
 
 #endif
+
+  $ cd $TESTTMP
+  $ cat >> $HGRCPATH <<EOF
+  > [commands]
+  > update.requiredest = True
+  > EOF
+  $ hg init dest
+  $ cd dest
+  $ echo a >> a
+  $ hg commit -qAm aa
+  $ hg up
+  abort: you must specify a destination
+  (for example: hg update ".::")
+  [255]
+  $ hg up .
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved