Optimize return value of util._matcher for common command line case This will trigger every time somebody runs something like "hg diff" or "hg status" without any arguments. The important part here is returning util.always as the match function, which is a much simpler (and faster) function than the usual return value, and allows other code to just skip the filtering if it knows all files will match.

#!/bin/sh

hg init
hg branch dummy # needed so -r "" doesn't point to the unnamed/default branch
touch a
hg add a
hg ci -m "a" -d "1000000 0"

echo 123 > b
hg add b
hg diff --nodates

hg diff --nodates -r tip

echo foo > a
hg diff --nodates

hg diff -r ""
hg diff -r tip -r ""

true