Auto merge of #30015 - petrochenkov:staged, r=brson

Closes #30008

`#[stable]`, `#[unstable]` and `#[rustc_deprecated]` are now guarded by `#[feature(staged_api)]`

r? @brson

Author: bors

src/doc/reference.md

@@ -2325,10 +2325,6 @@ The currently implemented features of the reference compiler are:
 * `simd_ffi` - Allows use of SIMD vectors in signatures for foreign functions.
                The SIMD interface is subject to change.
 
-* `staged_api` - Allows usage of stability markers and `#![staged_api]` in a
-                 crate. Stability markers are also attributes: `#[stable]`,
-                 `#[unstable]`, and `#[rustc_deprecated]` are the three levels.
-
 * `start` - Allows use of the `#[start]` attribute, which changes the entry point
             into a Rust program. This capability, especially the signature for the
             annotated function, is subject to change.

src/liballoc/lib.rs

@@ -60,7 +60,7 @@
 #![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "alloc"]
 #![crate_type = "rlib"]
-#![staged_api]
+#![cfg_attr(stage0, staged_api)]
 #![allow(unused_attributes)]
 #![unstable(feature = "alloc",
             reason = "this library is unlikely to be stabilized in its current \

src/liballoc_jemalloc/lib.rs

@@ -11,7 +11,7 @@
 #![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "alloc_jemalloc"]
 #![crate_type = "rlib"]
-#![staged_api]
+#![cfg_attr(stage0, staged_api)]
 #![no_std]
 #![cfg_attr(not(stage0), allocator)]
 #![cfg_attr(stage0, allow(improper_ctypes))]

src/liballoc_system/lib.rs

@@ -11,7 +11,7 @@
 #![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "alloc_system"]
 #![crate_type = "rlib"]
-#![staged_api]
+#![cfg_attr(stage0, staged_api)]
 #![no_std]
 #![cfg_attr(not(stage0), allocator)]
 #![cfg_attr(stage0, allow(improper_ctypes))]

src/libarena/lib.rs

@@ -23,7 +23,7 @@
 #![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "arena"]
 #![unstable(feature = "rustc_private", issue = "27812")]
-#![staged_api]
+#![cfg_attr(stage0, staged_api)]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",

src/libcollections/lib.rs

@@ -16,7 +16,7 @@
 // Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
 #![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "collections"]
-#![staged_api]
+#![cfg_attr(stage0, staged_api)]
 #![crate_type = "rlib"]
 #![unstable(feature = "collections",
             reason = "library is unlikely to be stabilized with the current \

src/libcore/lib.rs

@@ -56,7 +56,7 @@
             reason = "the libcore library has not yet been scrutinized for \
                       stabilization in terms of structure and naming",
             issue = "27701")]
-#![staged_api]
+#![cfg_attr(stage0, staged_api)]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
        html_favicon_url = "https://doc.rust-lang.org/favicon.ico",

src/libflate/lib.rs

@@ -18,7 +18,7 @@
 #![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "flate"]
 #![unstable(feature = "rustc_private", issue = "27812")]
-#![staged_api]
+#![cfg_attr(stage0, staged_api)]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",

src/libfmt_macros/lib.rs

@@ -18,7 +18,7 @@
 #![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "fmt_macros"]
 #![unstable(feature = "rustc_private", issue = "27812")]
-#![staged_api]
+#![cfg_attr(stage0, staged_api)]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",

src/libgetopts/lib.rs

@@ -84,7 +84,7 @@
 #![unstable(feature = "rustc_private",
             reason = "use the crates.io `getopts` library instead",
             issue = "27812")]
-#![staged_api]
+#![cfg_attr(stage0, staged_api)]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",