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3c0aac44d7
A static assertion is particularly appropriate when unsafe code relies
on two types to have the same size, or on some type to have a particular
size. This is a pattern I observed in USB code, for example:
ff7068402e/devices/src/usb/xhci/xhci_abi_schema.rs (522)
EXAMPLE:
extern crate assertions;
use assertions::const_assert;
fn main() {
const_assert!(std::mem::size_of::<String>() == 24);
}
EXAMPLE THAT FAILS TO COMPILE:
extern crate assertions;
use assertions::const_assert;
fn main() {
// fails to compile:
const_assert!(std::mem::size_of::<String>() == 8);
}
FAILURE LOOKS LIKE:
error[E0271]: type mismatch resolving `<[(); 0] as assertions::Expr>::Value == assertions::True`
--> src/main.rs:5:5
|
5 | const_assert!(std::mem::size_of::<String>() == 8);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected struct `assertions::True`, found struct `assertions::False`
TEST=`cargo test` the new crate
Change-Id: I6abe36d5a6a4bd4acb1a02e3aa7c1ece5357f007
Reviewed-on: https://chromium-review.googlesource.com/1366819
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: David Tolnay <dtolnay@chromium.org>
Reviewed-by: Dylan Reid <dgreid@chromium.org>
4 lines
86 B
TOML
4 lines
86 B
TOML
[package]
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name = "assertions"
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version = "0.1.0"
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authors = ["The Chromium OS Authors"]
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