libcore no longer compiles for targets with max-atomic-width = 0

[japaric]

due to some unused_macro warning and #![deny(warnings)]

STR

$ cargo build --target armv5te-unknown-linux-gnueabi --manifest-path $(rustc --print sysroot)/lib/rustlib/src/rust/src/libcore/Cargo.toml
   Compiling core v0.0.0 (file:///home/japaric/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore)
error: unused macro definition
    --> /home/japaric/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore/sync/atomic.rs:921:1
     |
921  | / macro_rules! atomic_int {
922  | |     ($stable:meta,
923  | |      $stable_cxchg:meta,
924  | |      $stable_debug:meta,
...    |
1328 | |     }
1329 | | }
     | |_^
     |
     = note: #[deny(unused_macros)] implied by #[deny(warnings)]
note: lint level defined here
    --> /home/japaric/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore/lib.rs:68:9
     |
68   | #![deny(warnings)]
     |         ^^^^^^^^

error: aborting due to previous error

error: Could not compile `core`.

To learn more, run the command again with --verbose.

Meta

$ rustc -V
rustc 1.19.0-nightly (0ed1ec9f9 2017-05-18)

[nagisa]

Isn’t it supposed to be a guranatee that ptr-sized atomics are always available? Is this a custom target of some sort?

[japaric]

Isn’t it supposed to be a guranatee that ptr-sized atomics are always available?

Hmm, no?

Is this a custom target of some sort?

At least two built-in targets have max-atomic-width = 0.