comparison tests/test-mv-cp-st-diff.t @ 18136:f23dea2b296e

copies: do not track backward copies, only renames (issue3739)

The inverse of a rename is a rename, but the inverse of a copy is not a copy.
Presenting it as such -- in particular, stuffing it into the same dict as real
copies -- causes bugs because other code starts believing the inverse copies
are real.

The only test whose output changes is test-mv-cp-st-diff.t. When a backwards
status -C command is run where a copy is involved, the inverse copy (which was
hitherto presented as a real copy) is no longer displayed.

Keeping track of inverse copies is useful in some situations -- composability
of diffs, for example, since adding "a" followed by an inverse copy "b" to "a"
is equivalent to a rename "b" to "a". However, representing them would require
a more complex data structure than the same dict in which real copies are also
stored.

18135:a6fe1b9cc68f

  
  # parent to root:
  
  % hg st -C --rev . --rev 0
  M a
    b
  R b
  
  % hg diff --git --rev . --rev 0
  diff --git a/a b/a
  --- a/a

  
  # parent to branch:
  
  % hg st -C --rev . --rev 2
  M a
    b
  A x/y
  R b
  
  % hg diff --git --rev . --rev 2
  diff --git a/a b/a

  
  # parent to root:
  
  % hg st -C --rev . --rev 0
  M a
    b
  R b
  R c
  
  % hg diff --git --rev . --rev 0
  diff --git a/a b/a

  
  # parent to branch:
  
  % hg st -C --rev . --rev 2
  M a
    b
  A x/y
  R b
  R c
  
  % hg diff --git --rev . --rev 2

18136:f23dea2b296e

  
  # parent to root:
  
  % hg st -C --rev . --rev 0
  M a
  R b
  
  % hg diff --git --rev . --rev 0
  diff --git a/a b/a
  --- a/a

  
  # parent to branch:
  
  % hg st -C --rev . --rev 2
  M a
  A x/y
  R b
  
  % hg diff --git --rev . --rev 2
  diff --git a/a b/a

  
  # parent to root:
  
  % hg st -C --rev . --rev 0
  M a
  R b
  R c
  
  % hg diff --git --rev . --rev 0
  diff --git a/a b/a

  
  # parent to branch:
  
  % hg st -C --rev . --rev 2
  M a
  A x/y
  R b
  R c
  
  % hg diff --git --rev . --rev 2