error[E0659]: `std` is ambiguous --> $DIR/ambiguity-macros-nested.rs:8:13 | LL | pub use std::io; | ^^^ ambiguous name | = note: ambiguous because of multiple potential import sources = note: `std` could refer to a built-in crate = help: use `::std` to refer to this crate unambiguously note: `std` could also refer to the module defined here --> $DIR/ambiguity-macros-nested.rs:13:13 | LL | / mod std { LL | | pub struct io; LL | | } | |_____________^ ... LL | m!(); | ---- in this macro invocation = help: use `self::std` to refer to this module unambiguously = note: this error originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info) error: aborting due to previous error For more information about this error, try `rustc --explain E0659`.