Function rustc_expand::mbe::macro_rules::is_in_follow
source ยท fn is_in_follow(tok: &TokenTree, kind: NonterminalKind) -> IsInFollow
Expand description
Returns true
if frag
can legally be followed by the token tok
. For
fragments that can consume an unbounded number of tokens, tok
must be within a well-defined follow set. This is intended to
guarantee future compatibility: for example, without this rule, if
we expanded expr
to include a new binary operator, we might
break macros that were relying on that binary operator as a
separator.