are feature gates for tuple indexing and slicing properly enforced?

[pnkfelix]

I have seen evidence that both tuple indexing and slicing syntax are silently allowed by rustc, rather than requiring the feature gate turned on to enable them.

It could be that I missed some step along the way where these features were officially enabled. But I think its more likely that someone has accidentally turned them both on somehow, especially since the team discussion from last Thursday on #18006 included statements that tuple-indexing is meant to be feature gated.

% cat /tmp/f.rs 
fn main() {
    let t = ('a', 'b', 'c');
    let v = vec!['x', 'y', 'z'];
    println!("t: {} v: {}", t.1, v[]);
}
% rustc-0.12-x64 --version=verbose
rustc 0.12.0 (ba4081a5a 2014-10-07 13:44:41 -0700)
binary: rustc
commit-hash: ba4081a5a8573875fed17545846f6f6902c8ba8d
commit-date: 2014-10-07 13:44:41 -0700
host: x86_64-apple-darwin
release: 0.12.0
% rustc-0.12-x64 /tmp/f.rs 
% rustc --version
rustc 0.13.0-dev (4480caf2a 2014-10-18 06:22:15 +0000)
% rustc /tmp/f.rs 
% ./f
t: b v: [x, y, z]
% 

[pnkfelix]

Note that I demonstrated running both the release (0.12) and a recent development (4480caf) build of rustc on the file that is using these features without the gate.

[nrc]

#18102 ?

[pnkfelix]

oh... right.

[pnkfelix]

(closing as duplicate of #18102 )