error: macro-expanded `extern crate` items cannot shadow names passed with `--extern` --> $DIR/extern-prelude-extern-crate-restricted-shadowing.rs:19:9 | LL | extern crate std as core; | ^^^^^^^^^^^^^^^^^^^^^^^^^ ... LL | define_other_core!(); | -------------------- in this macro invocation | = note: this error originates in the macro `define_other_core` (in Nightly builds, run with -Z macro-backtrace for more info) error[E0659]: `Vec` is ambiguous --> $DIR/extern-prelude-extern-crate-restricted-shadowing.rs:13:9 | LL | Vec::panic!(); | ^^^ ambiguous name | = note: ambiguous because of a conflict between a macro-expanded name and a less macro-expanded name from outer scope during import or macro resolution note: `Vec` could refer to the crate imported here --> $DIR/extern-prelude-extern-crate-restricted-shadowing.rs:5:9 | LL | extern crate std as Vec; | ^^^^^^^^^^^^^^^^^^^^^^^^ ... LL | define_vec!(); | ------------- in this macro invocation note: `Vec` could also refer to a struct from prelude --> $SRC_DIR/std/src/prelude/mod.rs:LL:COL = note: this error originates in the macro `define_vec` (in Nightly builds, run with -Z macro-backtrace for more info) error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0659`.