rust/src/doc/trpl/advanced-linking.md

% Advanced Linking

The common cases of linking with Rust have been covered earlier in this book,
but supporting the range of linking possibilities made available by other
languages is important for Rust to achieve seamless interaction with native
libraries.

# Link args

There is one other way to tell `rustc` how to customize linking, and that is via
the `link_args` attribute. This attribute is applied to `extern` blocks and
specifies raw flags which need to get passed to the linker when producing an
artifact. An example usage would be:

``` no_run
#![feature(link_args)]

#[link_args = "-foo -bar -baz"]
extern {}
# fn main() {}
```

Note that this feature is currently hidden behind the `feature(link_args)` gate
because this is not a sanctioned way of performing linking. Right now `rustc`
shells out to the system linker, so it makes sense to provide extra command line
arguments, but this will not always be the case. In the future `rustc` may use
LLVM directly to link native libraries, in which case `link_args` will have no
meaning.

It is highly recommended to *not* use this attribute, and rather use the more
formal `#[link(...)]` attribute on `extern` blocks instead.