Use a build script to detect if we can use MaybeUninit or NoDrop.
Enabling unstable features automatically is not ideal, but since it's
a soundness issue we should do it.
Use a MaybeUninit-like union on nightly when we can. We use a feature
detection script in build.rs, so that we also go back to the fallback if
the unstable feature changes in an unexpected way.
We need to continue to use NoDrop for best working stable
implementation, but we eagerly use our union solution where we can,
currently only in nightlies.
Rustc feature probe code written by Josh Stone (cuviper),
taken from num-bigint.
This way we cover all users up to 256 at least. The reason these are not
enabled by default is that they slow down the compilation of the crate
by a factor of 2-3x.
- Add try_insert / try_remove to be the old fallible variants that
return errors
- Insert that pushes out if full does no longer exist -- full vec is an
error
This implements serde support under the optional 'serde' feature, and adds unit tests to test said support.
https://serde.rs/unit-testing.html used as a guide for the unit tests - using 'serde_test' makes for much
less boilerplate here, but it does require that the project have a non-optional dev dependency on 'serde_test'.
ArrayVec::drop was not panic safe — if there would be a panic during an
element's drop, the discriminant would never be set to Dropped, and the
array elements would potentially double drop.
Fix this by going back to the old NoDrop composition. The NoDrop struct
thas its own Drop impl, that will trigger too on panic during an element's
drop. This serves to make ArrayVec::drop panic safe.
Also tweak IntoIter::drop to make it panic safe: set inner ArrayVec's
length before dropping any elements.
Thank you to @Stebalien for reporting this bug and providing the
excellent testcases in this commit.
Using NoDrop expands ArrayVec to have two drop flags again, but this
is a temporary tradeoff, drop flags will eventually go away.
Fixes#3
bluss