merge: fix crash on criss cross merge with dir move and delete (issue5020) stable

merge: fix crash on criss cross merge with dir move and delete (issue5020)

Work around that 'dm' in the data model only can have one operation for the
target file, but still can have multiple and conflicting operations on the
source file where the other operation is a 'rm'. The move would thus fail with
'abort: No such file or directory'.

In this case it is "obvious" that the file should be removed, either before or
after moving it. We thus keep the 'rm' of the source file but drop the 'dm'.

This is not a pretty fix but quite "obviously" safe (famous last words...) as
it only touches a rare code path that used to crash. It is possible that it
would be better to swap the files for 'dm' as suggested on
https://bz.mercurial-scm.org/show_bug.cgi?id=5020#c13 but it is not entirely
obvious that it not just would create conflicts on the other file. That can be
revisited later.

--- a/mercurial/merge.py	Tue Jan 31 03:20:07 2017 +0100
+++ b/mercurial/merge.py	Tue Jan 31 03:25:59 2017 +0100
@@ -997,6 +997,7 @@
         # Pick the best bid for each file
         repo.ui.note(_('\nauction for merging merge bids\n'))
         actions = {}
+        dms = [] # filenames that have dm actions
         for f, bids in sorted(fbids.items()):
             # bids is a mapping from action method to list af actions
             # Consensus?
@@ -1005,6 +1006,8 @@
                 if all(a == l[0] for a in l[1:]): # len(bids) is > 1
                     repo.ui.note(_(" %s: consensus for %s\n") % (f, m))
                     actions[f] = l[0]
+                    if m == 'dm':
+                        dms.append(f)
                     continue
             # If keep is an option, just do it.
             if 'k' in bids:
@@ -1029,7 +1032,19 @@
             repo.ui.warn(_(' %s: ambiguous merge - picked %s action\n') %
                          (f, m))
             actions[f] = l[0]
+            if m == 'dm':
+                dms.append(f)
             continue
+        # Work around 'dm' that can cause multiple actions for the same file
+        for f in dms:
+            dm, (f0, flags), msg = actions[f]
+            assert dm == 'dm', dm
+            m, args, msg = actions[f0]
+            if m == 'r':
+                # We have one bid for removing a file and another for moving it.
+                # These two could be merged as first move and then delete ...
+                # but instead drop moving and just delete.
+                del actions[f]
         repo.ui.note(_('end of auction\n\n'))
 
     _resolvetrivial(repo, wctx, mctx, ancestors[0], actions)

--- a/tests/test-merge-criss-cross.t	Tue Jan 31 03:20:07 2017 +0100
+++ b/tests/test-merge-criss-cross.t	Tue Jan 31 03:25:59 2017 +0100
@@ -11,9 +11,15 @@
 
   $ hg up -qr0
   $ echo '2 first change' > f2
+  $ mkdir d1
+  $ echo '0 base' > d1/f3
+  $ echo '0 base' > d1/f4
+  $ hg add -q d1
   $ hg ci -qm '2 first change f2'
 
   $ hg merge -qr 1
+  $ hg rm d1/f3
+  $ hg mv -q d1 d2
   $ hg ci -m '3 merge'
 
   $ hg up -qr2
@@ -24,38 +30,38 @@
   $ hg ci -m '5 second change f1'
 
   $ hg up -r3
-  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  2 files updated, 0 files merged, 2 files removed, 0 files unresolved
   $ echo '6 second change' > f2
   $ hg ci -m '6 second change f2'
 
   $ hg log -G
-  @  changeset:   6:3b08d01b0ab5
+  @  changeset:   6:6373bbfdae1d
   |  tag:         tip
-  |  parent:      3:cf89f02107e5
+  |  parent:      3:c202c8af058d
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     6 second change f2
   |
-  | o  changeset:   5:adfe50279922
+  | o  changeset:   5:e673248094b1
   | |  user:        test
   | |  date:        Thu Jan 01 00:00:00 1970 +0000
   | |  summary:     5 second change f1
   | |
-  | o    changeset:   4:7d3e55501ae6
-  | |\   parent:      2:40663881a6dd
+  | o    changeset:   4:177f58377c06
+  | |\   parent:      2:d1d156401c1b
   | | |  parent:      1:0f6b37dbe527
   | | |  user:        test
   | | |  date:        Thu Jan 01 00:00:00 1970 +0000
   | | |  summary:     4 merge
   | | |
-  o---+  changeset:   3:cf89f02107e5
-  | | |  parent:      2:40663881a6dd
+  o---+  changeset:   3:c202c8af058d
+  | | |  parent:      2:d1d156401c1b
   |/ /   parent:      1:0f6b37dbe527
   | |    user:        test
   | |    date:        Thu Jan 01 00:00:00 1970 +0000
   | |    summary:     3 merge
   | |
-  | o  changeset:   2:40663881a6dd
+  | o  changeset:   2:d1d156401c1b
   | |  parent:      0:40494bf2444c
   | |  user:        test
   | |  date:        Thu Jan 01 00:00:00 1970 +0000
@@ -73,27 +79,51 @@
   
 
   $ hg merge -v --debug --tool internal:dump 5 --config merge.preferancestor='!'
-  note: using 0f6b37dbe527 as ancestor of 3b08d01b0ab5 and adfe50279922
-        alternatively, use --config merge.preferancestor=40663881a6dd
+  note: using 0f6b37dbe527 as ancestor of 6373bbfdae1d and e673248094b1
+        alternatively, use --config merge.preferancestor=d1d156401c1b
     searching for copies back to rev 3
+    unmatched files in local:
+     d2/f4
+    unmatched files in other:
+     d1/f3
+     d1/f4
+    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
+     src: 'd1/f4' -> dst: 'd2/f4' 
+    checking for directory renames
+     discovered dir src: 'd1/' -> dst: 'd2/'
+     pending file src: 'd1/f3' -> dst: 'd2/f3'
+     pending file src: 'd1/f4' -> dst: 'd2/f4'
   resolving manifests
    branchmerge: True, force: False, partial: False
-   ancestor: 0f6b37dbe527, local: 3b08d01b0ab5+, remote: adfe50279922
+   ancestor: 0f6b37dbe527, local: 6373bbfdae1d+, remote: e673248094b1
+   preserving d2/f4 for resolve of d2/f4
    preserving f2 for resolve of f2
    f1: remote is newer -> g
   getting f1
+   d2/f3: local directory rename - get from d1/f3 -> dg
+  getting d1/f3 to d2/f3
+   d2/f4: local directory rename, both created -> m (premerge)
    f2: versions differ -> m (premerge)
   picked tool ':dump' for f2 (binary False symlink False changedelete False)
   merging f2
-  my f2@3b08d01b0ab5+ other f2@adfe50279922 ancestor f2@0f6b37dbe527
+  my f2@6373bbfdae1d+ other f2@e673248094b1 ancestor f2@0f6b37dbe527
    f2: versions differ -> m (merge)
   picked tool ':dump' for f2 (binary False symlink False changedelete False)
-  my f2@3b08d01b0ab5+ other f2@adfe50279922 ancestor f2@0f6b37dbe527
-  1 files updated, 0 files merged, 0 files removed, 1 files unresolved
+  my f2@6373bbfdae1d+ other f2@e673248094b1 ancestor f2@0f6b37dbe527
+  3 files updated, 0 files merged, 0 files removed, 1 files unresolved
   use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
   [1]
 
-  $ f --dump *
+  $ f --dump --recurse *
+  d2: directory with 2 files
+  d2/f3:
+  >>>
+  0 base
+  <<<
+  d2/f4:
+  >>>
+  0 base
+  <<<
   f1:
   >>>
   5 second change
@@ -121,11 +151,13 @@
 
   $ hg up -qC .
   $ hg merge -v --tool internal:dump 5 --config merge.preferancestor="null 40663881 3b08d"
-  note: using 40663881a6dd as ancestor of 3b08d01b0ab5 and adfe50279922
-        alternatively, use --config merge.preferancestor=0f6b37dbe527
+  note: using 0f6b37dbe527 as ancestor of 6373bbfdae1d and e673248094b1
+        alternatively, use --config merge.preferancestor=d1d156401c1b
   resolving manifests
-  merging f1
-  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
+  getting f1
+  getting d1/f3 to d2/f3
+  merging f2
+  3 files updated, 0 files merged, 0 files removed, 1 files unresolved
   use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
   [1]
 
@@ -134,36 +166,70 @@
   $ rm f*
   $ hg up -qC .
   $ hg merge -v --debug --tool internal:dump 5 --config merge.preferancestor="*"
-  note: merging 3b08d01b0ab5+ and adfe50279922 using bids from ancestors 0f6b37dbe527 and 40663881a6dd
+  note: merging 6373bbfdae1d+ and e673248094b1 using bids from ancestors 0f6b37dbe527 and d1d156401c1b
   
   calculating bids for ancestor 0f6b37dbe527
     searching for copies back to rev 3
+    unmatched files in local:
+     d2/f4
+    unmatched files in other:
+     d1/f3
+     d1/f4
+    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
+     src: 'd1/f4' -> dst: 'd2/f4' 
+    checking for directory renames
+     discovered dir src: 'd1/' -> dst: 'd2/'
+     pending file src: 'd1/f3' -> dst: 'd2/f3'
+     pending file src: 'd1/f4' -> dst: 'd2/f4'
   resolving manifests
    branchmerge: True, force: False, partial: False
-   ancestor: 0f6b37dbe527, local: 3b08d01b0ab5+, remote: adfe50279922
+   ancestor: 0f6b37dbe527, local: 6373bbfdae1d+, remote: e673248094b1
+   d2/f3: local directory rename - get from d1/f3 -> dg
+   d2/f4: local directory rename, both created -> m
    f1: remote is newer -> g
    f2: versions differ -> m
   
-  calculating bids for ancestor 40663881a6dd
+  calculating bids for ancestor d1d156401c1b
     searching for copies back to rev 3
+    unmatched files in local:
+     d2/f4
+    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
+     src: 'd1/f4' -> dst: 'd2/f4' 
+    checking for directory renames
+     discovered dir src: 'd1/' -> dst: 'd2/'
   resolving manifests
    branchmerge: True, force: False, partial: False
-   ancestor: 40663881a6dd, local: 3b08d01b0ab5+, remote: adfe50279922
+   ancestor: d1d156401c1b, local: 6373bbfdae1d+, remote: e673248094b1
    f1: versions differ -> m
    f2: remote unchanged -> k
   
   auction for merging merge bids
+   d2/f3: consensus for dg
+   d2/f4: consensus for m
    f1: picking 'get' action
    f2: picking 'keep' action
   end of auction
   
+   preserving d2/f4 for resolve of d2/f4
    f1: remote is newer -> g
   getting f1
    f2: remote unchanged -> k
-  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+   d2/f3: local directory rename - get from d1/f3 -> dg
+  getting d1/f3 to d2/f3
+   d2/f4: local directory rename, both created -> m (premerge)
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 
-  $ f --dump *
+  $ f --dump --recurse *
+  d2: directory with 2 files
+  d2/f3:
+  >>>
+  0 base
+  <<<
+  d2/f4:
+  >>>
+  0 base
+  <<<
   f1:
   >>>
   5 second change
@@ -177,38 +243,79 @@
 The other way around:
 
   $ hg up -C -r5
-  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  4 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg merge -v --debug --config merge.preferancestor="*"
-  note: merging adfe50279922+ and 3b08d01b0ab5 using bids from ancestors 0f6b37dbe527 and 40663881a6dd
+  note: merging e673248094b1+ and 6373bbfdae1d using bids from ancestors 0f6b37dbe527 and d1d156401c1b
   
   calculating bids for ancestor 0f6b37dbe527
     searching for copies back to rev 3
+    unmatched files in local:
+     d1/f3
+     d1/f4
+    unmatched files in other:
+     d2/f4
+    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
+     src: 'd1/f4' -> dst: 'd2/f4' 
+    checking for directory renames
+     discovered dir src: 'd1/' -> dst: 'd2/'
+     pending file src: 'd1/f3' -> dst: 'd2/f3'
+     pending file src: 'd1/f4' -> dst: 'd2/f4'
   resolving manifests
    branchmerge: True, force: False, partial: False
-   ancestor: 0f6b37dbe527, local: adfe50279922+, remote: 3b08d01b0ab5
+   ancestor: 0f6b37dbe527, local: e673248094b1+, remote: 6373bbfdae1d
+   d2/f3: remote directory rename - move from d1/f3 -> dm
+   d2/f4: remote directory rename, both created -> m
    f1: remote unchanged -> k
    f2: versions differ -> m
   
-  calculating bids for ancestor 40663881a6dd
+  calculating bids for ancestor d1d156401c1b
     searching for copies back to rev 3
+    unmatched files in other:
+     d2/f4
+    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
+     src: 'd1/f4' -> dst: 'd2/f4' 
+    checking for directory renames
+     discovered dir src: 'd1/' -> dst: 'd2/'
   resolving manifests
    branchmerge: True, force: False, partial: False
-   ancestor: 40663881a6dd, local: adfe50279922+, remote: 3b08d01b0ab5
+   ancestor: d1d156401c1b, local: e673248094b1+, remote: 6373bbfdae1d
+   d1/f3: other deleted -> r
+   d1/f4: other deleted -> r
+   d2/f4: remote created -> g
    f1: versions differ -> m
    f2: remote is newer -> g
   
   auction for merging merge bids
+   d1/f3: consensus for r
+   d1/f4: consensus for r
+   d2/f3: consensus for dm
+   d2/f4: picking 'get' action
    f1: picking 'keep' action
    f2: picking 'get' action
   end of auction
   
+   d1/f3: other deleted -> r
+  removing d1/f3
+   d1/f4: other deleted -> r
+  removing d1/f4
+   d2/f4: remote created -> g
+  getting d2/f4
    f2: remote is newer -> g
   getting f2
    f1: remote unchanged -> k
-  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  2 files updated, 0 files merged, 2 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 
-  $ f --dump *
+  $ f --dump --recurse *
+  d2: directory with 2 files
+  d2/f3:
+  >>>
+  0 base
+  <<<
+  d2/f4:
+  >>>
+  0 base
+  <<<
   f1:
   >>>
   5 second change
@@ -222,57 +329,85 @@
 
   $ hg up -qC
   $ hg merge
-  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  2 files updated, 0 files merged, 2 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 
   $ hg up -qC tip
   $ hg merge -v
-  note: merging 3b08d01b0ab5+ and adfe50279922 using bids from ancestors 0f6b37dbe527 and 40663881a6dd
+  note: merging 6373bbfdae1d+ and e673248094b1 using bids from ancestors 0f6b37dbe527 and d1d156401c1b
   
   calculating bids for ancestor 0f6b37dbe527
   resolving manifests
   
-  calculating bids for ancestor 40663881a6dd
+  calculating bids for ancestor d1d156401c1b
   resolving manifests
   
   auction for merging merge bids
+   d2/f3: consensus for dg
+   d2/f4: consensus for m
    f1: picking 'get' action
    f2: picking 'keep' action
   end of auction
   
   getting f1
-  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  getting d1/f3 to d2/f3
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 
   $ hg up -qC
   $ hg merge -v --debug --config merge.preferancestor="*"
-  note: merging 3b08d01b0ab5+ and adfe50279922 using bids from ancestors 0f6b37dbe527 and 40663881a6dd
+  note: merging 6373bbfdae1d+ and e673248094b1 using bids from ancestors 0f6b37dbe527 and d1d156401c1b
   
   calculating bids for ancestor 0f6b37dbe527
     searching for copies back to rev 3
+    unmatched files in local:
+     d2/f4
+    unmatched files in other:
+     d1/f3
+     d1/f4
+    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
+     src: 'd1/f4' -> dst: 'd2/f4' 
+    checking for directory renames
+     discovered dir src: 'd1/' -> dst: 'd2/'
+     pending file src: 'd1/f3' -> dst: 'd2/f3'
+     pending file src: 'd1/f4' -> dst: 'd2/f4'
   resolving manifests
    branchmerge: True, force: False, partial: False
-   ancestor: 0f6b37dbe527, local: 3b08d01b0ab5+, remote: adfe50279922
+   ancestor: 0f6b37dbe527, local: 6373bbfdae1d+, remote: e673248094b1
+   d2/f3: local directory rename - get from d1/f3 -> dg
+   d2/f4: local directory rename, both created -> m
    f1: remote is newer -> g
    f2: versions differ -> m
   
-  calculating bids for ancestor 40663881a6dd
+  calculating bids for ancestor d1d156401c1b
     searching for copies back to rev 3
+    unmatched files in local:
+     d2/f4
+    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
+     src: 'd1/f4' -> dst: 'd2/f4' 
+    checking for directory renames
+     discovered dir src: 'd1/' -> dst: 'd2/'
   resolving manifests
    branchmerge: True, force: False, partial: False
-   ancestor: 40663881a6dd, local: 3b08d01b0ab5+, remote: adfe50279922
+   ancestor: d1d156401c1b, local: 6373bbfdae1d+, remote: e673248094b1
    f1: versions differ -> m
    f2: remote unchanged -> k
   
   auction for merging merge bids
+   d2/f3: consensus for dg
+   d2/f4: consensus for m
    f1: picking 'get' action
    f2: picking 'keep' action
   end of auction
   
+   preserving d2/f4 for resolve of d2/f4
    f1: remote is newer -> g
   getting f1
    f2: remote unchanged -> k
-  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+   d2/f3: local directory rename - get from d1/f3 -> dg
+  getting d1/f3 to d2/f3
+   d2/f4: local directory rename, both created -> m (premerge)
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
 
   $ cd ..