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Fix lang items box example code

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The `exchange_free` lang item is gone in favour of `box_free` [1].

Some warnings are also fixed by this commit.

[1]: ca115dd083
This commit is contained in:
Volker Mische 2018-02-01 00:21:43 +01:00 • committed by GitHub
parent 560a2f4faf
commit cf78ff3913
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 9 additions and 14 deletions
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23
src/doc/unstable-book/src/language-features/lang-items.md
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@ -37,28 +37,23 @@ unsafe fn allocate(size: usize, _align: usize) -> *mut u8 {
p
}
#[lang = "exchange_free"]
unsafe fn deallocate(ptr: *mut u8, _size: usize, _align: usize) {
#[lang = "box_free"]
unsafe fn box_free<T: ?Sized>(ptr: *mut T) {
libc::free(ptr as *mut libc::c_void)
}
#[lang = "box_free"]
unsafe fn box_free<T: ?Sized>(ptr: *mut T) {
deallocate(ptr as *mut u8, ::core::mem::size_of_val(&*ptr), ::core::mem::align_of_val(&*ptr));
}
#[start]
fn main(argc: isize, argv: *const *const u8) -> isize {
let x = box 1;
fn main(_argc: isize, _argv: *const *const u8) -> isize {
let _x = box 1;
0
}
#[lang = "eh_personality"] extern fn rust_eh_personality() {}
#[lang = "panic_fmt"] extern fn rust_begin_panic() -> ! { unsafe { intrinsics::abort() } }
# #[lang = "eh_unwind_resume"] extern fn rust_eh_unwind_resume() {}
# #[no_mangle] pub extern fn rust_eh_register_frames () {}
# #[no_mangle] pub extern fn rust_eh_unregister_frames () {}
#[lang = "eh_unwind_resume"] extern fn rust_eh_unwind_resume() {}
#[no_mangle] pub extern fn rust_eh_register_frames () {}
#[no_mangle] pub extern fn rust_eh_unregister_frames () {}
```
Note the use of `abort`: the `exchange_malloc` lang item is assumed to
@ -80,7 +75,7 @@ Other features provided by lang items include:
Lang items are loaded lazily by the compiler; e.g. if one never uses
`Box` then there is no need to define functions for `exchange_malloc`
and `exchange_free`. `rustc` will emit an error when an item is needed
and `box_free`. `rustc` will emit an error when an item is needed
but not found in the current crate or any that it depends on.
Most lang items are defined by `libcore`, but if you're trying to build
@ -318,4 +313,4 @@ the source code.
- `phantom_data`: `libcore/marker.rs`
- `freeze`: `libcore/marker.rs`
- `debug_trait`: `libcore/fmt/mod.rs`
- `non_zero`: `libcore/nonzero.rs`
- `non_zero`: `libcore/nonzero.rs`