Function token_tree_to_syntax_node 

pub fn token_tree_to_syntax_node(
    tt: &TopSubtree,
    entry_point: TopEntryPoint,
    span_to_edition: &mut dyn FnMut(SyntaxContext) -> Edition,
) -> (Parse<SyntaxNode>, SpanMap)
where
    SyntaxContext: Copy + Debug + PartialEq + Eq + Hash,

Converts a tt::Subtree back to a SyntaxNode. The produced SpanMap contains a mapping from the syntax nodes offsets to the subtree’s spans.