comparison mercurial/copies.py @ 23071:652ab726ba93 stable

amend: fix amending rename commit with diverged topologies (issue4405)

This addresses the bug described in issue4405: when obsolescence markers are
enabled, amending a commit with a file move can lead to the copy information
being lost.

However, the bug is more general and can be reproduced without obsmarkers as
well, as demonstracted by Pierre-Yves and put into the updated test.
Specifically, graph topology divergences between the filelogs and the changelog
can cause copy information to be lost during amends.

23070:c289fb3624b8

    if s == -1:
        return ""
    return f[:s]

def _findlimit(repo, a, b):
    """Find the earliest revision that's an ancestor of a or b but not both,
    None if no such revision exists.
    """
    # basic idea:
    # - mark a and b with different sides
    # - if a parent's children are all on the same side, the parent is
    #   on that side, otherwise it is on no side
    # - walk the graph in topological order with the help of a heap;

            limit = r # lowest rev visited
            interesting -= 1

    if not hascommonancestor:
        return None
    return limit

def _chain(src, dst, a, b):
    '''chain two sets of copies a->b'''
    t = a.copy()
    for k, v in b.iteritems():

23071:652ab726ba93

    if s == -1:
        return ""
    return f[:s]

def _findlimit(repo, a, b):
    """
    Find the last revision that needs to be checked to ensure that a full
    transitive closure for file copies can be properly calculated.
    Generally, this means finding the earliest revision number that's an
    ancestor of a or b but not both, except when a or b is a direct descendent
    of the other, in which case we can return the minimum revnum of a and b.
    None if no such revision exists.
    """

    # basic idea:
    # - mark a and b with different sides
    # - if a parent's children are all on the same side, the parent is
    #   on that side, otherwise it is on no side
    # - walk the graph in topological order with the help of a heap;

            limit = r # lowest rev visited
            interesting -= 1

    if not hascommonancestor:
        return None

    # Consider the following flow (see test-commit-amend.t under issue4405):
    # 1/ File 'a0' committed
    # 2/ File renamed from 'a0' to 'a1' in a new commit (call it 'a1')
    # 3/ Move back to first commit
    # 4/ Create a new commit via revert to contents of 'a1' (call it 'a1-amend')
    # 5/ Rename file from 'a1' to 'a2' and commit --amend 'a1-msg'
    #
    # During the amend in step five, we will be in this state:
    #
    # @  3 temporary amend commit for a1-amend
    # |
    # o  2 a1-amend
    # |
    # | o  1 a1
    # |/
    # o  0 a0
    #
    # When findlimit is called, a and b are revs 3 and 0, so limit will be 2,
    # yet the filelog has the copy information in rev 1 and we will not look
    # back far enough unless we also look at the a and b as candidates.
    # This only occurs when a is a descendent of b or visa-versa.
    return min(limit, a, b)

def _chain(src, dst, a, b):
    '''chain two sets of copies a->b'''
    t = a.copy()
    for k, v in b.iteritems():