remove support for the #[start] attribute

tests/ui/error-codes/E0132.rs

@@ -1,7 +0,0 @@
-#![feature(start)]
-
-#[start]
-fn f< T >() {} //~ ERROR E0132
-
-fn main() {
-}

tests/ui/error-codes/E0132.stderr

@@ -1,9 +0,0 @@
-error[E0132]: `#[start]` function is not allowed to have type parameters
-  --> $DIR/E0132.rs:4:5
-   |
-LL | fn f< T >() {}
-   |     ^^^^^ `#[start]` function cannot have type parameters
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0132`.

tests/ui/error-codes/E0138.rs

@@ -1,8 +0,0 @@
-#![feature(start)]
-
-#[start]
-fn foo(argc: isize, argv: *const *const u8) -> isize { 0 }
-
-#[start]
-fn f(argc: isize, argv: *const *const u8) -> isize { 0 }
-//~^ ERROR E0138

tests/ui/error-codes/E0138.stderr

@@ -1,12 +0,0 @@
-error[E0138]: multiple `start` functions
-  --> $DIR/E0138.rs:7:1
-   |
-LL | fn foo(argc: isize, argv: *const *const u8) -> isize { 0 }
-   | ---------------------------------------------------- previous `#[start]` function here
-...
-LL | fn f(argc: isize, argv: *const *const u8) -> isize { 0 }
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ multiple `start` functions
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0138`.

tests/ui/error-codes/E0647.rs

@@ -1,9 +0,0 @@
-#![no_std]
-#![feature(start)]
-
-extern crate std;
-
-#[start]
-fn start(_: isize, _: *const *const u8) -> isize where (): Copy { //~ ERROR [E0647]
-    0
-}

tests/ui/error-codes/E0647.stderr

@@ -1,9 +0,0 @@
-error[E0647]: `#[start]` function is not allowed to have a `where` clause
-  --> $DIR/E0647.rs:7:50
-   |
-LL | fn start(_: isize, _: *const *const u8) -> isize where (): Copy {
-   |                                                  ^^^^^^^^^^^^^^ `#[start]` function cannot have a `where` clause
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0647`.