Parse fully-qualified associated types in generics without whitespace
Parse fully-qualified associated types in generics without whitespace

This breaks code that looks like this:

    let x = foo as bar << 13;

Change such code to look like this:

    let x = (foo as bar) << 13;

Closes #17362.

[breaking-change]

retep998/rand,ebfull/rand,huonw/rand,GrahamDennis/rand,bluss/rand,achanda/rand,waynenilsen/rand,shepmaster/rand,bhickey/rand,arthurprs/rand