Definition: "kidney blame" == "blame -r N:M" with M<N. Currently it is an error (raised by svn_client_blame5()).
By and large, it should do exactly what 'blame -r M:N' does: walk the revisions from "before-the-colon revision" to "after-the-colon revision" and then print the contents of the "after the colon" revision, with each line annotated by the revnum of the "rightmost" (that is: nearest to the revnum on the right of the colon) revision within the range that added that line. In other words, if (iota@4, kappa@1), (iota@3, kappa@2), (iota@2, kappa@3), (iota@1, kappa@4) are pairs of byte-for-byte-identical files, then 'blame -r 1:4 kappa' and 'blame -r 4:1 iota' will output the same thing. Currently, the non-kidney blame checks one revision before the start --- that is, 'blame -r M:N' actually calls svn_ra_get_file_revs2(start=M-1, end=N). The purpose of this is to differentiate "lines added in rN" from "lines present since before rN". That makes 'blame -r M:N' correspond to 'diff -r M-1:N' or 'diff -c M:N', in that it also shows changes made _by_ rM, not only _since_ rM. That behaviour cannot easily replicated for the -r N:M case since it's not possible to cheaply find the "next interesting revision" after rN, but in any case I think it shouldn't be: 'blame -r M:N' should not have automagically decremented M --- instead, if the user had wanted to see what lines were added in rM, as opposed to before it, the user should have specified M-1 as the start revision. That way, 'blame -r M:N' would be consistent with 'diff -r M:N'. So I suggest that blame -r N:M not try to find the "next change after rN" (that's the analogous thing to what "decrement M" is in the '-r M:N' case). That means -r M:N and -r N:M are assymetrical, and I propose we fix that by making -r M:N not decrement M --- which we can probably only do in 2.0. --- Another issue: what should 'blame -r 3:3' do? Currently it is allowed, and prints '-' for lines added before r3 and '3' for lines added in r3. I am not sure whether that is intentional / by design, or just an accident of the fact that whoever added the 'end_rev < start_rev' check should have used the broader condition 'end_rev <= start_rev' instead. (See r7438 <-> http://svn.apache.org/r847512). It seems to me it should ideally print '3' for every line, and the user should pass '-r 2:3' if he wants to distinguish "added in r3" from "added before r3". It would be easy to preserve the current behaviour, though, of printing '-' rather than '2' (where '2' here is the youngest change to that line, for lines added before r3). --- Cheers, Daniel
