# 
# 
# patch "ChangeLog"
#  from [35e146a9c36218f8f55750f957fb14bc489cccbf]
#    to [e49d9cea0ea66e2c20628a77999e4d622930ced5]
# 
# patch "cmd_diff_log.cc"
#  from [eea68109f73eb58ad1488bc454e10182c28bafe5]
#    to [769806240271dce3dc01c5af4e55d74821a2ef6d]
# 
# patch "tests/two_parent_workspace_commands_that_fail/__driver__.lua"
#  from [a1b540beddc4f9c24881c22e9fd26f9f6e88a706]
#    to [4ac3985a30348b3d51c911af46749ba9e30ddca8]
# 
============================================================
--- ChangeLog	35e146a9c36218f8f55750f957fb14bc489cccbf
+++ ChangeLog	e49d9cea0ea66e2c20628a77999e4d622930ced5
@@ -1,5 +1,8 @@ 2007-02-07  Zack Weinberg  <address@hidden
 2007-02-07  Zack Weinberg  <address@hidden>
 
+	* cmd_diff_log.cc (prepare_diff): Handle multi-parent workspaces
+	gracefully.
+
 	* tests/two_parent_workspace_commands_that_fail
 	* tests/two_parent_workspace_pluck: New tests (expected to fail).
 	* testsuite.lua: Add them.
============================================================
--- cmd_diff_log.cc	eea68109f73eb58ad1488bc454e10182c28bafe5
+++ cmd_diff_log.cc	769806240271dce3dc01c5af4e55d74821a2ef6d
@@ -359,10 +359,19 @@ prepare_diff(cset & included,
     {
       roster_t new_roster, old_roster;
       revision_id old_rid;
+      parent_map parents;
 
-      app.work.get_base_and_current_roster_shape(old_roster, new_roster, nis);
-      app.work.get_revision_id(old_rid);
+      app.work.get_parent_rosters(parents);
 
+      // With no arguments, which parent should we diff against?
+      N(parents.size() == 1,
+        F("this workspace has more than one parent\n"
+          "(specify a revision to diff against with --revision)"));
+
+      old_rid = parents.begin()->first;
+      old_roster = *(parents.begin()->second.first);
+      app.work.get_current_roster_shape(new_roster, nis);
+
       node_restriction mask(args_to_paths(args),
                             args_to_paths(app.opts.exclude_patterns),
                             app.opts.depth,
@@ -385,13 +394,9 @@ prepare_diff(cset & included,
       N(app.db.revision_exists(r_old_id),
         F("no such revision '%s'") % r_old_id);
 
-      app.work.get_base_and_current_roster_shape(old_roster, new_roster, nis);
-      // Clobber old_roster with the one specified
       app.db.get_roster(r_old_id, old_roster);
+      app.work.get_current_roster_shape(new_roster, nis);
 
-      // FIXME: handle no ancestor case
-      // N(r_new.edges.size() == 1, F("current revision has no ancestor"));
-
       node_restriction mask(args_to_paths(args),
                             args_to_paths(app.opts.exclude_patterns), 
                             app.opts.depth,
@@ -480,7 +485,7 @@ CMD(diff, N_("informative"), N_("[PATH].
   bool new_is_archived;
   
   prepare_diff(included, app, args, new_is_archived, revs);
-  
+
   data summary;
   write_cset(included, summary);
 
============================================================
--- tests/two_parent_workspace_commands_that_fail/__driver__.lua	a1b540beddc4f9c24881c22e9fd26f9f6e88a706
+++ tests/two_parent_workspace_commands_that_fail/__driver__.lua	4ac3985a30348b3d51c911af46749ba9e30ddca8
@@ -24,10 +24,19 @@ diag = "mtn: misuse: this command can on
 check(not qgrep("ancestor", "testfile"))
 
 diag = "mtn: misuse: this command can only be used in a single-parent workspace\n"
+diffdiag = ("mtn: misuse: this workspace has more than one parent\n"..
+	    "mtn: misuse: (specify a revision to diff against with --revision)\n")
 
 check(mtn("merge_into_workspace", anc), 1, nil, diag)
 
-xfail(mtn("diff"), 1, nil, diag)
+-- diff with no arguments: what parent?
+check(mtn("diff"), 1, nil, diffdiag)
+check(mtn("automate", "content_diff"), 1, nil, diffdiag)
+
+-- diff can do something sensible if you specify a parent
+check(mtn("diff", "-r", left), 0, false, nil)
+check(mtn("automate", "content_diff", "-r", right), 0, false, nil)
+
 xfail(mtn("revert"), 1, nil, diag)
 xfail(mtn("update"), 1, nil, diag)