A unique ID associated with a macro invocation and expansion.
The ID of the theoretical expansion that generates freshly parsed, unexpanded AST. Invariant: we do not create any ExpnId with local_id == 0 and krate != 0.
expn_id.outer_expn_is_descendant_of(ctxt) is equivalent to but faster than
Returns span for the macro which originally caused this expansion to happen.
Stops backtracing at include! boundary.
Returns the argument unchanged.
Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain
repr(...) attributes. Please see the Rust Reference’s “Type Layout” chapter for details on type layout guarantees.
Size: 8 bytes