Missed this review comment.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/
7229084
return compile(expr, syntax.POSIX, true)
}
-// Longest sets the match semantics of the regexp to leftmost-longest.
+// Longest makes future searches prefer the leftmost-longest match.
// That is, when matching against text, the regexp returns a match that
// begins as early as possible in the input (leftmost), and among those
// it chooses a match that is as long as possible.