rust/src/librustc_back/lib.rs
Brian Anderson c27133e2ce Preliminary feature staging
This partially implements the feature staging described in the
[release channel RFC][rc]. It does not yet fully conform to the RFC as
written, but does accomplish its goals sufficiently for the 1.0 alpha
release.

It has three primary user-visible effects:

* On the nightly channel, use of unstable APIs generates a warning.
* On the beta channel, use of unstable APIs generates a warning.
* On the beta channel, use of feature gates generates a warning.

Code that does not trigger these warnings is considered 'stable',
modulo pre-1.0 bugs.

Disabling the warnings for unstable APIs continues to be done in the
existing (i.e. old) style, via `#[allow(...)]`, not that specified in
the RFC. I deem this marginally acceptable since any code that must do
this is not using the stable dialect of Rust.

Use of feature gates is itself gated with the new 'unstable_features'
lint, on nightly set to 'allow', and on beta 'warn'.

The attribute scheme used here corresponds to an older version of the
RFC, with the `#[staged_api]` crate attribute toggling the staging
behavior of the stability attributes, but the user impact is only
in-tree so I'm not concerned about having to make design changes later
(and I may ultimately prefer the scheme here after all, with the
`#[staged_api]` crate attribute).

Since the Rust codebase itself makes use of unstable features the
compiler and build system to a midly elaborate dance to allow it to
bootstrap while disobeying these lints (which would otherwise be
errors because Rust builds with `-D warnings`).

This patch includes one significant hack that causes a
regression. Because the `format_args!` macro emits calls to unstable
APIs it would trigger the lint.  I added a hack to the lint to make it
not trigger, but this in turn causes arguments to `println!` not to be
checked for feature gates. I don't presently understand macro
expansion well enough to fix. This is bug #20661.

Closes #16678

[rc]: https://github.com/rust-lang/rfcs/blob/master/text/0507-release-channels.md
2015-01-07 15:34:56 -08:00

51 lines
1.6 KiB
Rust

// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Some stuff used by rustc that doesn't have many dependencies
//!
//! Originally extracted from rustc::back, which was nominally the
//! compiler 'backend', though LLVM is rustc's backend, so rustc_back
//! is really just odds-and-ends relating to code gen and linking.
//! This crate mostly exists to make rustc smaller, so we might put
//! more 'stuff' here in the future. It does not have a dependency on
//! rustc_llvm.
//!
//! FIXME: Split this into two crates: one that has deps on syntax, and
//! one that doesn't; the one that doesn't might get decent parallel
//! build speedups.
#![crate_name = "rustc_back"]
#![experimental]
#![staged_api]
#![crate_type = "dylib"]
#![crate_type = "rlib"]
#![doc(html_logo_url = "http://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
html_favicon_url = "http://www.rust-lang.org/favicon.ico",
html_root_url = "http://doc.rust-lang.org/nightly/")]
#![feature(slicing_syntax)]
extern crate syntax;
extern crate serialize;
#[macro_use] extern crate log;
pub mod abi;
pub mod archive;
pub mod arm;
pub mod fs;
pub mod mips;
pub mod mipsel;
pub mod rpath;
pub mod sha2;
pub mod svh;
pub mod target_strs;
pub mod x86;
pub mod x86_64;
pub mod target;