diff --git a/src/doc/trpl/no-stdlib.md b/src/doc/trpl/no-stdlib.md index 9abcd330989..5fca05d5340 100644 --- a/src/doc/trpl/no-stdlib.md +++ b/src/doc/trpl/no-stdlib.md @@ -4,14 +4,6 @@ By default, `std` is linked to every Rust crate. In some contexts, this is undesirable, and can be avoided with the `#![no_std]` attribute attached to the crate. -```ignore -// a minimal library -#![crate_type="lib"] -#![feature(no_std)] -#![no_std] -# // fn main() {} tricked you, rustdoc! -``` - Obviously there's more to life than just libraries: one can use `#[no_std]` with an executable, controlling the entry point is possible in two ways: the `#[start]` attribute, or overriding the @@ -21,7 +13,10 @@ The function marked `#[start]` is passed the command line parameters in the same format as C: ```rust -#![feature(lang_items, start, no_std, libc)] +# #![feature(libc)] +#![feature(lang_items)] +#![feature(start)] +#![feature(no_std)] #![no_std] // Pull in the system libc library for what crt0.o likely requires @@ -47,11 +42,13 @@ with `#![no_main]` and then create the appropriate symbol with the correct ABI and the correct name, which requires overriding the compiler's name mangling too: -```ignore +```rust +# #![feature(libc)] #![feature(no_std)] +#![feature(lang_items)] +#![feature(start)] #![no_std] #![no_main] -#![feature(lang_items, start)] extern crate libc; @@ -92,19 +89,24 @@ instead. The core library has very few dependencies and is much more portable than the standard library itself. Additionally, the core library has most of the -necessary functionality for writing idiomatic and effective Rust code. +necessary functionality for writing idiomatic and effective Rust code. When +using `#![no_std]`, Rust will automatically inject the `core` crate, just like +we do for `std` when we’re using it. As an example, here is a program that will calculate the dot product of two vectors provided from C, using idiomatic Rust practices. -```ignore -#![feature(lang_items, start, no_std, core, libc)] +```rust +# #![feature(libc)] +#![feature(lang_items)] +#![feature(start)] +#![feature(no_std)] +#![feature(core)] +#![feature(core_slice_ext)] +#![feature(raw)] #![no_std] -# extern crate libc; -extern crate core; - -use core::prelude::*; +extern crate libc; use core::mem;