icasefs: make case-folding collision detection as rename aware (issue3370)

if the file in target context causes case-folding collision against
one in working context, current implementation aborts merging with it,
even thouhg collding one (in target) is the file renamed from collided
one (in working).

this patch uses file copy information to know whether colliding file
is renamed from collided one or not: if so, collision between them is
ignored.

this patch also avoids collision detection between current context and
target context, if working context is clean (with --check/-c) or will
be clean (with --clean/-C).

mercurial/merge.py

@@ -1,595 +1,607 b''
 # merge.py - directory-level update/merge handling for Mercurial
 #
 # Copyright 2006, 2007 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from node import nullid, nullrev, hex, bin
 from i18n import _
 import scmutil, util, filemerge, copies, subrepo
 import errno, os, shutil
 
 class mergestate(object):
     '''track 3-way merge state of individual files'''
     def __init__(self, repo):
         self._repo = repo
         self._dirty = False
         self._read()
     def reset(self, node=None):
         self._state = {}
         if node:
             self._local = node
         shutil.rmtree(self._repo.join("merge"), True)
         self._dirty = False
     def _read(self):
         self._state = {}
         try:
             f = self._repo.opener("merge/state")
             for i, l in enumerate(f):
                 if i == 0:
                     self._local = bin(l[:-1])
                 else:
                     bits = l[:-1].split("\0")
                     self._state[bits[0]] = bits[1:]
             f.close()
         except IOError, err:
             if err.errno != errno.ENOENT:
                 raise
         self._dirty = False
     def commit(self):
         if self._dirty:
             f = self._repo.opener("merge/state", "w")
             f.write(hex(self._local) + "\n")
             for d, v in self._state.iteritems():
                 f.write("\0".join([d] + v) + "\n")
             f.close()
             self._dirty = False
     def add(self, fcl, fco, fca, fd, flags):
         hash = util.sha1(fcl.path()).hexdigest()
         self._repo.opener.write("merge/" + hash, fcl.data())
         self._state[fd] = ['u', hash, fcl.path(), fca.path(),
                            hex(fca.filenode()), fco.path(), flags]
         self._dirty = True
     def __contains__(self, dfile):
         return dfile in self._state
     def __getitem__(self, dfile):
         return self._state[dfile][0]
     def __iter__(self):
         l = self._state.keys()
         l.sort()
         for f in l:
             yield f
     def mark(self, dfile, state):
         self._state[dfile][0] = state
         self._dirty = True
     def resolve(self, dfile, wctx, octx):
         if self[dfile] == 'r':
             return 0
         state, hash, lfile, afile, anode, ofile, flags = self._state[dfile]
         f = self._repo.opener("merge/" + hash)
         self._repo.wwrite(dfile, f.read(), flags)
         f.close()
         fcd = wctx[dfile]
         fco = octx[ofile]
         fca = self._repo.filectx(afile, fileid=anode)
         r = filemerge.filemerge(self._repo, self._local, lfile, fcd, fco, fca)
         if r is None:
             # no real conflict
             del self._state[dfile]
         elif not r:
             self.mark(dfile, 'r')
         return r
 
 def _checkunknownfile(repo, wctx, mctx, f):
     return (not repo.dirstate._ignore(f)
         and os.path.exists(repo.wjoin(f))
         and repo.dirstate.normalize(f) not in repo.dirstate
         and mctx[f].cmp(wctx[f]))
 
 def _checkunknown(repo, wctx, mctx):
     "check for collisions between unknown files and files in mctx"
 
     error = False
     for f in mctx:
         if f not in wctx and _checkunknownfile(repo, wctx, mctx, f):
             error = True
             wctx._repo.ui.warn(_("%s: untracked file differs\n") % f)
     if error:
         raise util.Abort(_("untracked files in working directory differ "
                            "from files in requested revision"))
 
 def _checkcollision(mctx, wctx):
     "check for case folding collisions in the destination context"
     folded = {}
     for fn in mctx:
         fold = util.normcase(fn)
         if fold in folded:
             raise util.Abort(_("case-folding collision between %s and %s")
                              % (fn, folded[fold]))
         folded[fold] = fn
 
     if wctx:
+        # class to delay looking up copy mapping
+        class pathcopies(object):
+            @util.propertycache
+            def map(self):
+                # {dst@mctx: src@wctx} copy mapping
+                return copies.pathcopies(wctx, mctx)
+        pc = pathcopies()
+
         for fn in wctx:
             fold = util.normcase(fn)
             mfn = folded.get(fold, None)
-            if mfn and (mfn != fn):
+            if mfn and mfn != fn and pc.map.get(mfn) != fn:
                 raise util.Abort(_("case-folding collision between %s and %s")
                                  % (mfn, fn))
 
 def _forgetremoved(wctx, mctx, branchmerge):
     """
     Forget removed files
 
     If we're jumping between revisions (as opposed to merging), and if
     neither the working directory nor the target rev has the file,
     then we need to remove it from the dirstate, to prevent the
     dirstate from listing the file when it is no longer in the
     manifest.
 
     If we're merging, and the other revision has removed a file
     that is not present in the working directory, we need to mark it
     as removed.
     """
 
     action = []
     state = branchmerge and 'r' or 'f'
     for f in wctx.deleted():
         if f not in mctx:
             action.append((f, state))
 
     if not branchmerge:
         for f in wctx.removed():
             if f not in mctx:
                 action.append((f, "f"))
 
     return action
 
 def manifestmerge(repo, p1, p2, pa, overwrite, partial):
     """
     Merge p1 and p2 with ancestor pa and generate merge action list
 
     overwrite = whether we clobber working files
     partial = function to filter file lists
     """
 
     def fmerge(f, f2, fa):
         """merge flags"""
         a, m, n = ma.flags(fa), m1.flags(f), m2.flags(f2)
         if m == n: # flags agree
             return m # unchanged
         if m and n and not a: # flags set, don't agree, differ from parent
             r = repo.ui.promptchoice(
                 _(" conflicting flags for %s\n"
                   "(n)one, e(x)ec or sym(l)ink?") % f,
                 (_("&None"), _("E&xec"), _("Sym&link")), 0)
             if r == 1:
                 return "x" # Exec
             if r == 2:
                 return "l" # Symlink
             return ""
         if m and m != a: # changed from a to m
             return m
         if n and n != a: # changed from a to n
             if (n == 'l' or a == 'l') and m1.get(f) != ma.get(f):
                 # can't automatically merge symlink flag when there
                 # are file-level conflicts here, let filemerge take
                 # care of it
                 return m
             return n
         return '' # flag was cleared
 
     def act(msg, m, f, *args):
         repo.ui.debug(" %s: %s -> %s\n" % (f, msg, m))
         action.append((f, m) + args)
 
     action, copy = [], {}
 
     if overwrite:
         pa = p1
     elif pa == p2: # backwards
         pa = p1.p1()
     elif pa and repo.ui.configbool("merge", "followcopies", True):
         copy, diverge = copies.mergecopies(repo, p1, p2, pa)
         for of, fl in diverge.iteritems():
             act("divergent renames", "dr", of, fl)
 
     repo.ui.note(_("resolving manifests\n"))
     repo.ui.debug(" overwrite: %s, partial: %s\n"
                   % (bool(overwrite), bool(partial)))
     repo.ui.debug(" ancestor: %s, local: %s, remote: %s\n" % (pa, p1, p2))
 
     m1, m2, ma = p1.manifest(), p2.manifest(), pa.manifest()
     copied = set(copy.values())
 
     if '.hgsubstate' in m1:
         # check whether sub state is modified
         for s in p1.substate:
             if p1.sub(s).dirty():
                 m1['.hgsubstate'] += "+"
                 break
 
     # Compare manifests
     for f, n in m1.iteritems():
         if partial and not partial(f):
             continue
         if f in m2:
             rflags = fmerge(f, f, f)
             a = ma.get(f, nullid)
             if n == m2[f] or m2[f] == a: # same or local newer
                 # is file locally modified or flags need changing?
                 # dirstate flags may need to be made current
                 if m1.flags(f) != rflags or n[20:]:
                     act("update permissions", "e", f, rflags)
             elif n == a: # remote newer
                 act("remote is newer", "g", f, rflags)
             else: # both changed
                 act("versions differ", "m", f, f, f, rflags, False)
         elif f in copied: # files we'll deal with on m2 side
             pass
         elif f in copy:
             f2 = copy[f]
             if f2 not in m2: # directory rename
                 act("remote renamed directory to " + f2, "d",
                     f, None, f2, m1.flags(f))
             else: # case 2 A,B/B/B or case 4,21 A/B/B
                 act("local copied/moved to " + f2, "m",
                     f, f2, f, fmerge(f, f2, f2), False)
         elif f in ma: # clean, a different, no remote
             if n != ma[f]:
                 if repo.ui.promptchoice(
                     _(" local changed %s which remote deleted\n"
                       "use (c)hanged version or (d)elete?") % f,
                     (_("&Changed"), _("&Delete")), 0):
                     act("prompt delete", "r", f)
                 else:
                     act("prompt keep", "a", f)
             elif n[20:] == "a": # added, no remote
                 act("remote deleted", "f", f)
             else:
                 act("other deleted", "r", f)
 
     for f, n in m2.iteritems():
         if partial and not partial(f):
             continue
         if f in m1 or f in copied: # files already visited
             continue
         if f in copy:
             f2 = copy[f]
             if f2 not in m1: # directory rename
                 act("local renamed directory to " + f2, "d",
                     None, f, f2, m2.flags(f))
             elif f2 in m2: # rename case 1, A/A,B/A
                 act("remote copied to " + f, "m",
                     f2, f, f, fmerge(f2, f, f2), False)
             else: # case 3,20 A/B/A
                 act("remote moved to " + f, "m",
                     f2, f, f, fmerge(f2, f, f2), True)
         elif f not in ma:
             if (not overwrite
                 and _checkunknownfile(repo, p1, p2, f)):
                 rflags = fmerge(f, f, f)
                 act("remote differs from untracked local",
                     "m", f, f, f, rflags, False)
             else:
                 act("remote created", "g", f, m2.flags(f))
         elif n != ma[f]:
             if repo.ui.promptchoice(
                 _("remote changed %s which local deleted\n"
                   "use (c)hanged version or leave (d)eleted?") % f,
                 (_("&Changed"), _("&Deleted")), 0) == 0:
                 act("prompt recreating", "g", f, m2.flags(f))
 
     return action
 
 def actionkey(a):
     return a[1] == 'r' and -1 or 0, a
 
 def applyupdates(repo, action, wctx, mctx, actx, overwrite):
     """apply the merge action list to the working directory
 
     wctx is the working copy context
     mctx is the context to be merged into the working copy
     actx is the context of the common ancestor
 
     Return a tuple of counts (updated, merged, removed, unresolved) that
     describes how many files were affected by the update.
     """
 
     updated, merged, removed, unresolved = 0, 0, 0, 0
     ms = mergestate(repo)
     ms.reset(wctx.p1().node())
     moves = []
     action.sort(key=actionkey)
 
     # prescan for merges
     for a in action:
         f, m = a[:2]
         if m == 'm': # merge
             f2, fd, flags, move = a[2:]
             if f == '.hgsubstate': # merged internally
                 continue
             repo.ui.debug("preserving %s for resolve of %s\n" % (f, fd))
             fcl = wctx[f]
             fco = mctx[f2]
             if mctx == actx: # backwards, use working dir parent as ancestor
                 if fcl.parents():
                     fca = fcl.p1()
                 else:
                     fca = repo.filectx(f, fileid=nullrev)
             else:
                 fca = fcl.ancestor(fco, actx)
             if not fca:
                 fca = repo.filectx(f, fileid=nullrev)
             ms.add(fcl, fco, fca, fd, flags)
             if f != fd and move:
                 moves.append(f)
 
     audit = scmutil.pathauditor(repo.root)
 
     # remove renamed files after safely stored
     for f in moves:
         if os.path.lexists(repo.wjoin(f)):
             repo.ui.debug("removing %s\n" % f)
             audit(f)
             os.unlink(repo.wjoin(f))
 
     numupdates = len(action)
     for i, a in enumerate(action):
         f, m = a[:2]
         repo.ui.progress(_('updating'), i + 1, item=f, total=numupdates,
                          unit=_('files'))
         if f and f[0] == "/":
             continue
         if m == "r": # remove
             repo.ui.note(_("removing %s\n") % f)
             audit(f)
             if f == '.hgsubstate': # subrepo states need updating
                 subrepo.submerge(repo, wctx, mctx, wctx, overwrite)
             try:
                 util.unlinkpath(repo.wjoin(f))
             except OSError, inst:
                 if inst.errno != errno.ENOENT:
                     repo.ui.warn(_("update failed to remove %s: %s!\n") %
                                  (f, inst.strerror))
             removed += 1
         elif m == "m": # merge
             if f == '.hgsubstate': # subrepo states need updating
                 subrepo.submerge(repo, wctx, mctx, wctx.ancestor(mctx), overwrite)
                 continue
             f2, fd, flags, move = a[2:]
             repo.wopener.audit(fd)
             r = ms.resolve(fd, wctx, mctx)
             if r is not None and r > 0:
                 unresolved += 1
             else:
                 if r is None:
                     updated += 1
                 else:
                     merged += 1
             if (move and repo.dirstate.normalize(fd) != f
                 and os.path.lexists(repo.wjoin(f))):
                 repo.ui.debug("removing %s\n" % f)
                 audit(f)
                 os.unlink(repo.wjoin(f))
         elif m == "g": # get
             flags = a[2]
             repo.ui.note(_("getting %s\n") % f)
             t = mctx.filectx(f).data()
             repo.wwrite(f, t, flags)
             t = None
             updated += 1
             if f == '.hgsubstate': # subrepo states need updating
                 subrepo.submerge(repo, wctx, mctx, wctx, overwrite)
         elif m == "d": # directory rename
             f2, fd, flags = a[2:]
             if f:
                 repo.ui.note(_("moving %s to %s\n") % (f, fd))
                 audit(f)
                 t = wctx.filectx(f).data()
                 repo.wwrite(fd, t, flags)
                 util.unlinkpath(repo.wjoin(f))
             if f2:
                 repo.ui.note(_("getting %s to %s\n") % (f2, fd))
                 t = mctx.filectx(f2).data()
                 repo.wwrite(fd, t, flags)
             updated += 1
         elif m == "dr": # divergent renames
             fl = a[2]
             repo.ui.warn(_("note: possible conflict - %s was renamed "
                            "multiple times to:\n") % f)
             for nf in fl:
                 repo.ui.warn(" %s\n" % nf)
         elif m == "e": # exec
             flags = a[2]
             repo.wopener.audit(f)
             util.setflags(repo.wjoin(f), 'l' in flags, 'x' in flags)
     ms.commit()
     repo.ui.progress(_('updating'), None, total=numupdates, unit=_('files'))
 
     return updated, merged, removed, unresolved
 
 def recordupdates(repo, action, branchmerge):
     "record merge actions to the dirstate"
 
     for a in action:
         f, m = a[:2]
         if m == "r": # remove
             if branchmerge:
                 repo.dirstate.remove(f)
             else:
                 repo.dirstate.drop(f)
         elif m == "a": # re-add
             if not branchmerge:
                 repo.dirstate.add(f)
         elif m == "f": # forget
             repo.dirstate.drop(f)
         elif m == "e": # exec change
             repo.dirstate.normallookup(f)
         elif m == "g": # get
             if branchmerge:
                 repo.dirstate.otherparent(f)
             else:
                 repo.dirstate.normal(f)
         elif m == "m": # merge
             f2, fd, flag, move = a[2:]
             if branchmerge:
                 # We've done a branch merge, mark this file as merged
                 # so that we properly record the merger later
                 repo.dirstate.merge(fd)
                 if f != f2: # copy/rename
                     if move:
                         repo.dirstate.remove(f)
                     if f != fd:
                         repo.dirstate.copy(f, fd)
                     else:
                         repo.dirstate.copy(f2, fd)
             else:
                 # We've update-merged a locally modified file, so
                 # we set the dirstate to emulate a normal checkout
                 # of that file some time in the past. Thus our
                 # merge will appear as a normal local file
                 # modification.
                 if f2 == fd: # file not locally copied/moved
                     repo.dirstate.normallookup(fd)
                 if move:
                     repo.dirstate.drop(f)
         elif m == "d": # directory rename
             f2, fd, flag = a[2:]
             if not f2 and f not in repo.dirstate:
                 # untracked file moved
                 continue
             if branchmerge:
                 repo.dirstate.add(fd)
                 if f:
                     repo.dirstate.remove(f)
                     repo.dirstate.copy(f, fd)
                 if f2:
                     repo.dirstate.copy(f2, fd)
             else:
                 repo.dirstate.normal(fd)
                 if f:
                     repo.dirstate.drop(f)
 
 def update(repo, node, branchmerge, force, partial, ancestor=None):
     """
     Perform a merge between the working directory and the given node
 
     node = the node to update to, or None if unspecified
     branchmerge = whether to merge between branches
     force = whether to force branch merging or file overwriting
     partial = a function to filter file lists (dirstate not updated)
 
     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, on the same named
     branch, or on another named branch).
 
     This logic is tested by test-update-branches.t.
 
     -c  -C  dirty  rev  |  linear   same  cross
      n   n    n     n   |    ok     (1)     x
      n   n    n     y   |    ok     ok     ok
      n   n    y     *   |   merge   (2)    (2)
      n   y    *     *   |    ---  discard  ---
      y   n    y     *   |    ---    (3)    ---
      y   n    n     *   |    ---    ok     ---
      y   y    *     *   |    ---    (4)    ---
 
     x = can't happen
     * = don't-care
     1 = abort: crosses branches (use 'hg merge' or 'hg update -c')
     2 = abort: crosses branches (use 'hg merge' to merge or
                  use 'hg update -C' to discard changes)
     3 = abort: uncommitted local changes
     4 = incompatible options (checked in commands.py)
 
     Return the same tuple as applyupdates().
     """
 
     onode = node
     wlock = repo.wlock()
     try:
         wc = repo[None]
         if node is None:
             # tip of current branch
             try:
                 node = repo.branchtags()[wc.branch()]
             except KeyError:
                 if wc.branch() == "default": # no default branch!
                     node = repo.lookup("tip") # update to tip
                 else:
                     raise util.Abort(_("branch %s not found") % wc.branch())
         overwrite = force and not branchmerge
         pl = wc.parents()
         p1, p2 = pl[0], repo[node]
         if ancestor:
             pa = repo[ancestor]
         else:
             pa = p1.ancestor(p2)
 
         fp1, fp2, xp1, xp2 = p1.node(), p2.node(), str(p1), str(p2)
 
         ### check phase
         if not overwrite and len(pl) > 1:
             raise util.Abort(_("outstanding uncommitted merges"))
         if branchmerge:
             if pa == p2:
                 raise util.Abort(_("merging with a working directory ancestor"
                                    " has no effect"))
             elif pa == p1:
                 if p1.branch() == p2.branch():
                     raise util.Abort(_("nothing to merge"),
                                      hint=_("use 'hg update' "
                                             "or check 'hg heads'"))
             if not force and (wc.files() or wc.deleted()):
                 raise util.Abort(_("outstanding uncommitted changes"),
                                  hint=_("use 'hg status' to list changes"))
             for s in wc.substate:
                 if wc.sub(s).dirty():
                     raise util.Abort(_("outstanding uncommitted changes in "
                                        "subrepository '%s'") % s)
 
         elif not overwrite:
             if pa == p1 or pa == p2: # linear
                 pass # all good
             elif wc.dirty(missing=True):
                 raise util.Abort(_("crosses branches (merge branches or use"
                                    " --clean to discard changes)"))
             elif onode is None:
                 raise util.Abort(_("crosses branches (merge branches or update"
                                    " --check to force update)"))
             else:
                 # Allow jumping branches if clean and specific rev given
                 pa = p1
 
         ### calculate phase
         action = []
         folding = not util.checkcase(repo.path)
         if folding:
-            _checkcollision(p2, branchmerge and p1)
+            # collision check is not needed for clean update
+            if not branchmerge and force:
+                _checkcollision(p2, None)
+            else:
+                _checkcollision(p2, wc)
         if not force:
             _checkunknown(repo, wc, p2)
         action += _forgetremoved(wc, p2, branchmerge)
         action += manifestmerge(repo, wc, p2, pa, overwrite, partial)
 
         ### apply phase
         if not branchmerge: # just jump to the new rev
             fp1, fp2, xp1, xp2 = fp2, nullid, xp2, ''
         if not partial:
             repo.hook('preupdate', throw=True, parent1=xp1, parent2=xp2)
 
         stats = applyupdates(repo, action, wc, p2, pa, overwrite)
 
         if not partial:
             repo.dirstate.setparents(fp1, fp2)
             recordupdates(repo, action, branchmerge)
             if not branchmerge:
                 repo.dirstate.setbranch(p2.branch())
     finally:
         wlock.release()
 
     if not partial:
         repo.hook('update', parent1=xp1, parent2=xp2, error=stats[3])
     return stats

tests/test-casecollision-merge.t

@@ -1,109 +1,209 b''
 run only on case-insensitive filesystems
 
   $ "$TESTDIR/hghave" icasefs || exit 80
 
 ################################
 test for branch merging
 ################################
 
-  $ hg init repo1
-  $ cd repo1
-
-create base revision
+test for rename awareness of case-folding collision check:
 
-  $ echo base > base.txt
-  $ hg add base.txt
-  $ hg commit -m 'base'
+(1) colliding file is one renamed from collided file:
+this is also case for issue3370.
 
-add same file in different case on both heads
+  $ hg init merge_renameaware_1
+  $ cd merge_renameaware_1
 
-  $ echo a > a.txt
-  $ hg add a.txt
-  $ hg commit -m 'add a.txt'
-
+  $ echo a > a
+  $ hg add a
+  $ hg commit -m '#0'
+  $ hg rename a tmp
+  $ hg rename tmp A
+  $ hg commit -m '#1'
   $ hg update 0
-  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
-
-  $ echo A > A.TXT
-  $ hg add A.TXT
-  $ hg commit -m 'add A.TXT'
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ echo 'modified at #2' > a
+  $ hg commit -m '#2'
   created new head
 
-merge another, and fail with case-folding collision
+  $ hg merge
+  merging a and A to A
+  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg status -A
+  M A
+    a
+  R a
+  $ cat A
+  modified at #2
+
+  $ hg update --clean 1
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg merge
+  merging A and a to A
+  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg status -A
+  M A
+    a
+  $ cat A
+  modified at #2
+
+  $ cd ..
+
+(2) colliding file is not related to collided file
+
+  $ hg init merge_renameaware_2
+  $ cd merge_renameaware_2
+
+  $ echo a > a
+  $ hg add a
+  $ hg commit -m '#0'
+  $ hg remove a
+  $ hg commit -m '#1'
+  $ echo A > A
+  $ hg add A
+  $ hg commit -m '#2'
+  $ hg update --clean 0
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ echo 'modified at #3' > a
+  $ hg commit -m '#3'
+  created new head
 
   $ hg merge
-  abort: case-folding collision between a.txt and A.TXT
+  abort: case-folding collision between A and a
   [255]
+  $ hg parents --template '{rev}\n'
+  3
+  $ hg status -A
+  C a
+  $ cat a
+  modified at #3
 
-check clean-ness of working directory
-
-  $ hg status
+  $ hg update --clean 2
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg merge
+  abort: case-folding collision between a and A
+  [255]
   $ hg parents --template '{rev}\n'
   2
+  $ hg status -A
+  C A
+  $ cat A
+  A
+
   $ cd ..
 
+
 ################################
 test for linear updates
 ################################
 
-  $ hg init repo2
-  $ cd repo2
+test for rename awareness of case-folding collision check:
 
-create base revision (rev:0)
+(1) colliding file is one renamed from collided file
+
+  $ hg init linearupdate_renameaware_1
+  $ cd linearupdate_renameaware_1
 
-  $ hg import --bypass --exact - <<EOF
-  > # HG changeset patch
-  > # User null
-  > # Date 1 0
-  > # Node ID e1bdf414b0ea9c831fd3a14e94a0a18e1410f98b
-  > # Parent  0000000000000000000000000000000000000000
-  > add a
-  > 
-  > diff --git a/a b/a
-  > new file mode 100644
-  > --- /dev/null
-  > +++ b/a
-  > @@ -0,0 +1,3 @@
-  > +this is line 1
-  > +this is line 2
-  > +this is line 3
-  > EOF
-  applying patch from stdin
-
-create rename revision (rev:1)
-
-  $ hg import --bypass --exact - <<EOF
-  > # HG changeset patch
-  > # User null
-  > # Date 1 0
-  > # Node ID 9dca9f19bb91851bc693544b598b0740629edfad
-  > # Parent  e1bdf414b0ea9c831fd3a14e94a0a18e1410f98b
-  > rename a to A
-  > 
-  > diff --git a/a b/A
-  > rename from a
-  > rename to A
-  > EOF
-  applying patch from stdin
-
-update to base revision, and modify 'a'
+  $ echo a > a
+  $ hg add a
+  $ hg commit -m '#0'
+  $ hg rename a tmp
+  $ hg rename tmp A
+  $ hg commit -m '#1'
 
   $ hg update 0
-  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
-  $ echo 'this is added line' >> a
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
 
-update to current tip linearly
-
+  $ echo 'this is added line' >> a
   $ hg update 1
   merging a and A to A
   0 files updated, 1 files merged, 0 files removed, 0 files unresolved
-
-check status and contents of file
-
   $ hg status -A
   M A
   $ cat A
-  this is line 1
-  this is line 2
-  this is line 3
+  a
   this is added line
+
+  $ cd ..
+
+(2) colliding file is not related to collided file
+
+  $ hg init linearupdate_renameaware_2
+  $ cd linearupdate_renameaware_2
+
+  $ echo a > a
+  $ hg add a
+  $ hg commit -m '#0'
+  $ hg remove a
+  $ hg commit -m '#1'
+  $ echo A > A
+  $ hg add A
+  $ hg commit -m '#2'
+
+  $ hg update 0
+  abort: case-folding collision between a and A
+  [255]
+  $ hg parents --template '{rev}\n'
+  2
+  $ hg status -A
+  C A
+  $ cat A
+  A
+
+  $ hg update --check 0
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg parents --template '{rev}\n'
+  0
+  $ hg status -A
+  C a
+  $ cat a
+  a
+
+  $ hg update --clean 2
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg parents --template '{rev}\n'
+  2
+  $ hg status -A
+  C A
+  $ cat A
+  A
+
+  $ cd ..
+
+(3) colliding file is not related to collided file: added in working dir
+
+  $ hg init linearupdate_renameaware_3
+  $ cd linearupdate_renameaware_3
+
+  $ echo a > a
+  $ hg add a
+  $ hg commit -m '#0'
+  $ hg rename a b
+  $ hg commit -m '#1'
+  $ hg update 0
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+
+  $ echo B > B
+  $ hg add B
+  $ hg status
+  A B
+  $ hg update
+  abort: case-folding collision between b and B
+  [255]
+
+  $ hg update --check
+  abort: uncommitted local changes
+  [255]
+
+  $ hg update --clean
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg parents --template '{rev}\n'
+  1
+  $ hg status -A
+  C b
+  $ cat b
+  a
+
+  $ cd ..