Cargo suppresses output for warnings, but not for related notes.

[Ms2ger]

For example, compiling rust-mozjs as part of Servo yields

/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:1387:1: 1390:2 note: the `#[repr(C)]` attribute is attached here
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:1387 pub struct JSAutoCompartment {
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:1388     pub cx_: *mut JSContext,
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:1389     pub oldCompartment_: *mut JSCompartment,
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:1390 }
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:1302:1: 1304:2 note: the `#[repr(C)]` attribute is attached here
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:1302 pub struct JSAutoRequest {
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:1303     pub mContext: *mut JSContext,
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:1304 }
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:573:1: 575:2 note: the `#[repr(C)]` attribute is attached here
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:573 pub struct Heap<T: GCMethods<T> + Copy> {
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:574     pub ptr: UnsafeCell<T>,
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:575 }
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:592:1: 596:2 note: the `#[repr(C)]` attribute is attached here
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:592 pub struct Rooted<T> {
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:593     pub stack: *mut *mut Rooted<*mut ::libc::c_void>,
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:594     pub prev: *mut Rooted<*mut ::libc::c_void>,
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:595     pub ptr: T,
/home/servo/.cargo/git/checkouts/rust-mozjs-ebb4917e843c0a11/master/src/jsapi.rs:596 }

but not the warnings those notes are about.

[alexcrichton]

Unfortunately this is actually a bug in the compiler where the note message isn't paired well with the warning message, but could you open an issue in the rust-lang/rust repo instead of Cargo?