The function resolveLocation can be used for resolving location
descriptors and strings. Resolving is done with a modified version of RFC
3986's resolution algorithm in which the trailing URL segment is not removed. This allows a <Link> to be resolved relative to the <Route> that is is located in. resolveLocation supports pathnames that include double dot notation (../foo).

The function simpleResolve can be used for resolving <Route> and <Switch>
pathnames. This simply joins the pathname (iff it is not absolute) to the
base pathname using a forward slash.

The parent match is passed to matchPath. match.url is used for resolving instead of math.path to simplify matching (just match a string instead of having to parse params). matchPath will combine its parent's params with its params (favoring its params when there are conflicts)