pub type TypeMapKey = (u32, u32);Expand description
Key for type map: (span.start, span.end) for exact span lookup.
When multiple nodes share the same span (e.g. an identifier that is both a primary expr and
a var decl name), the type_map may store one entry per span; LSP/hover should prefer the
innermost or declaration node as appropriate (e.g. use node_at_offset and look up the
node’s text range).