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.