log: add -L/--line-range option to follow file history by line range We add an experimental -L/--line-range option to 'hg log' taking file patterns along with a line range using the (new) FILE,FROMLINE-TOLINE syntax where FILE may be a pattern (matching exactly one file). The resulting history is similar to what the "followlines" revset except that, if --patch is specified, only diff hunks within specified line range are shown. Basically, this brings the CLI on par with what currently only exists in hgweb through line selection in "file" and "annotate" views resulting in a file log with filtered patch to only display followed line range. The option may be specified multiple times and can be combined with --rev and regular file patterns to further restrict revisions. Usage of this option requires --follow; revisions are shown in descending order and renames are followed. Only the --graph option is currently not supported. The UI is the result of a consensus from review feedback at: https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-October/106749.html The implementation spreads between commands.log() and cmdutil module. In commands.log(), the main loop may now use a "hunksfilter" factory (similar to "filematcher") that, for a given "rev", produces a filtering function for diff hunks for a given file context object. The logic to build revisions from -L/--line-range options lives in cmdutil.getloglinerangerevs() which produces "revs", "filematcher" and "hunksfilter" information. Revisions obtained by following files' line range are filtered if they do not match the revset specified by --rev option. If regular FILE arguments are passed along with -L options, both filematchers are combined into a new matcher. .. feature:: Add an experimental -L/--line-range FILE,FROMLINE-TOLINE option to 'hg log' command to follow the history of files by line range. In combination with -p/--patch option, only diff hunks within specified line range will be displayed. Feedback, especially on UX aspects, is welcome.

diff: pass a diff hunks filter function from changeset_printer to patch.diff() We add a 'hunksfilterfn' keyword argument in all functions of the call stack from changeset_printer.show() to patch.diff(). This is a callable that will be used to filter out hunks by line range and will be used in the "-L/--line-range" option of "hg log" command introduced in the following changesets.

diff: also yield file context objects in patch.trydiff() (API) And retrieve them in patch.diffhunks(). We'll use these in forthcoming changesets to filter diff hunks by line range.

revset: extract a parsefollowlinespattern helper function We'll need the same logic in forthcoming changeset to handle --line-range option in 'hg log' command. The function lives in scmutil.py (rather than util.py) as it uses match and pathutil modules.

obsfate: add obsfate to default mapfile Use the verbosity aware template keyword introduced earlier. It has the nice property of being verbosity dependent but in order to customize the obsfate part, users will need to replace the lobsfate definition from default mapfile with the one using template functions (by copying the one from test-obsmarker- template.t for example). As it's a more advanced use-case, I'm more inclined to have the same code for the {obsfate} keyword, in the changeset printer and in the default mapfile for consistency. But, the definition in default mapfile could be replaced with one based on template filter to obsfate output customization if it is a big need for users.

log: add obsfate by default in changeset printer Having an obsfate by default in log will be useful for users to understand why they have obsolete and unstable changesets. Obsfate will only be shown for obsolete changesets, which only happens if people opt-in to experimental feature. But when obsolete changeset are visible, it is very useful to understand where they are. Having it in log could be sufficient for most people, so they don't have to learn a new command (like obslog which is itself useful in case of divergences). For example, when pulling and working directory parent become obsolete: $ hg pull ... working directory parent is obsolete! (f936c1697205) This message comes from the Evolve extension. Obsfate would comes handy: $ hg log -G o changeset: 2:6f91013c5136 | tag: tip | parent: 0:4ef7b558f3ec | user: Boris Feld <boris.feld@octobus.net> | date: Mon Oct 09 16:00:27 2017 +0200 | summary: A | | @ changeset: 1:f936c1697205 |/ user: Boris Feld <boris.feld@octobus.net> | date: Mon Oct 09 16:00:27 2017 +0200 | obsfate: rewritten using amend as 2:6f91013c5136 | summary: -A | o changeset: 0:feb4dd822b8c user: Boris Feld <boris.feld@octobus.net> date: Tue Oct 09 16:00:00 2017 +0200 summary: ROOT And once we update, we don't have an obsolete changeset in the log anymore so we don't show obsfate anymore, most users won't see obsfate often if they don't have obsolete changeset often: @ changeset: 2:6f91013c5136 | tag: tip | parent: 0:4ef7b558f3ec | user: Boris Feld <boris.feld@octobus.net> | date: Mon Oct 09 16:00:27 2017 +0200 | summary: A | o changeset: 0:feb4dd822b8c user: Boris Feld <boris.feld@octobus.net> date: Tue Oct 09 16:00:00 2017 +0200 summary: ROOT

obsfate: only display date in verbose mode The date is also not that helpful in most cases but we show it in verbose mode.