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Mention target_arch conditional compilation

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Adam Greig
2018-11-27 17:12:34 +00:00
committed by Adam Greig
parent 6e8271ea5c
commit 52a01b6f53
1 changed files with 13 additions and 5 deletions
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src/c-tips/index.md
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@@ -54,11 +54,19 @@ pub mod iir;
You can similarly include code blocks only if a feature is _not_ enabled, or if
any combination or features is or is not enabled.
The feature selection will only apply to the next statement or block. If a block can not be used in the current scope then then `cfg` attribute will need to be used multiple times.
It's worth noting that most of the time it is better to simply include all the
code and allow the compiler to remove dead code when optimising: it's simpler
for you and your users, and in general the compiler will do a good job of
removing unused code.
Additionally, Rust provides a number of automatically-set conditions you can
use, such as `target_arch` to select different code based on architecture. For
full details of the conditional compilation support, refer to the [Rust
Reference].
[Rust Reference]: https://doc.rust-lang.org/reference/conditional-compilation.html
The conditional compilation will only apply to the next statement or block. If
a block can not be used in the current scope then then `cfg` attribute will
need to be used multiple times. It's worth noting that most of the time it is
better to simply include all the code and allow the compiler to remove dead
code when optimising: it's simpler for you and your users, and in general the
compiler will do a good job of removing unused code.
### Compile-Time Sizes and Computation