Function rustc_expand::mbe::transcribe::lockstep_iter_size

fn lockstep_iter_size(
    tree: &TokenTree, 
    interpolations: &FxHashMap<MacroRulesNormalizedIdent, NamedMatch>, 
    repeats: &[(usize, usize)]
) -> LockstepIterSize

Given a tree, make sure that all sequences have the same length as the matches for the appropriate meta-vars in interpolations.

Note that if repeats does not match the exact correct depth of a meta-var, lookup_cur_matched will return None, which is why this still works even in the presence of multiple nested matcher sequences.