Auto merge of #21257 - alexcrichton:issue-20064, r=pnkfelix

These two attributes are used to change the entry point into a Rust program, but
for now they're being put behind feature gates until we have a chance to think
about them a little more. The #[start] attribute specifically may have its
signature changed.

This is a breaking change to due the usage of these attributes generating errors
by default now. If your crate is using these attributes, add this to your crate
root:

    #![feature(start)] // if you're using the #[start] attribute
    #![feature(main)]  // if you're using the #[main] attribute

cc #20064

src/test/run-pass/attr-main-2.rs

@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(main)]
 
 pub fn main() {
     panic!()

src/test/run-pass/attr-main.rs

@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(main)]
 
 #[main]
 fn foo() {

src/test/run-pass/attr-start.rs

@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(start)]
 
 #[start]
 fn start(_argc: int, _argv: *const *const u8) -> int {

src/test/run-pass/attr.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(main)]
+
 #[main]
 fn foo() {
 }

src/test/run-pass/intrinsic-alignment.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(intrinsics)]
+#![feature(intrinsics, main)]
 
 mod rusti {
     extern "rust-intrinsic" {

src/test/run-pass/issue-16597-empty.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 
 // compile-flags:--test
+// no-pretty-expanded
 
 // This verifies that the test generation doesn't crash when we have
 // no tests - for more information, see PR #16892.

src/test/run-pass/issue-20823.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 
 // compile-flags: --test
+// no-pretty-expanded
 
 #![deny(unstable)]
 

src/test/run-pass/lang-item-public.rs

@@ -13,7 +13,7 @@
 // ignore-windows #13361
 
 #![no_std]
-#![feature(lang_items)]
+#![feature(lang_items, start)]
 
 extern crate "lang-item-public" as lang_lib;
 

src/test/run-pass/native-print-no-runtime.rs

@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(start)]
 
 #[start]
 pub fn main(_: int, _: *const *const u8) -> int {

src/test/run-pass/running-with-no-runtime.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(start)]
+
 use std::ffi;
 use std::io::process::{Command, ProcessOutput};
 use std::os;

src/test/run-pass/smallest-hello-world.rs

@@ -13,7 +13,7 @@
 // Smallest "hello world" with a libc runtime
 
 #![no_std]
-#![feature(intrinsics, lang_items)]
+#![feature(intrinsics, lang_items, start)]
 
 extern crate libc;
 

src/test/run-pass/use.rs

@@ -9,14 +9,13 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-
 #![allow(unused_imports)]
-
+#![feature(start)]
 #![no_std]
+
 extern crate std;
 extern crate "std" as zed;
 
-
 use std::str;
 use zed::str as x;
 mod baz {

src/test/run-pass/vec-macro-no-std.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(lang_items)]
+#![feature(lang_items, start)]
 #![no_std]
 
 extern crate "std" as other;