help: describe about choice of :prompt as a fallback merge tool explicitly "merge-tools" help topic has described that the merge of the file fails if no tool is found to merge binary or symlink, since c77f6276c9e7 (or Mercurial 1.7), which based on (already removed) MergeProgram wiki page. But even at that revision, and of course now, merge of the file doesn't fail automatically for binary/symlink. ":prompt" (or equivalent logic) is used, if there is no appropriate tool configuration for binary/symlink.

wix: only one KeyPath is allowed per Component

dirstate: optimize walk() by using match.visitdir() We already have the logic for restricting directory walks in match.visitdir() that we use for treemanifests. We should take advantage of it when walking the working copy as well. This speeds up "hg st -I rootfilesin:." on the Firefox repo from 0.587s to 0.305s on warm disk (and much more on cold disk). More time is spent reading the dirstate than walking the working copy after. I tried to find scenarios where calling match.visitdir() would be a noticeable overhead, but I couldn't find any. I encourage the reader to try for themselves, since this is performance-critical code.

match: optimize visitdir() for patterns matching only root directory Because _rootsanddirs() returns a list of directories to visit recursively and a list of directories to visit non-recursively. For patterns such as 'rootfilesin:foo/bar', we clearly need to visit the directory foo/bar, but we also need to visit its parents. The method therefore uses util.dirs() to find the parent directories of 'foo/bar'. That method does not include the root directory, but since we obviously need to visit the root directory, we always added '.' to the set of directories to visit non-recursively. The visitdir() method had special handling to consider set(['.']) to mean that no includes had been specified and would thus visit all directories. However, when the pattern is 'rootfilesin:.', set(['.']) is actually the real set of directories to visit and the special handling of that set meant that all directories got visited instead of just the root directory. The fix is simple: add '.' to the set of parent directories in _rootsanddirs() and stop treating set(['.']) specially. This makes hg files -r . -I rootfilesin:. in a treemanifest version of the Firefox repo go from 1.5s to 0.26s on warm disk (and a *much* bigger improvement on cold disk). Note that the -I is necessary for no good reason. We just haven't optimized visitdir() for regular (non-include, non-exclude) patterns yet.