On 30.03.23 17:00, Alice Ryhl wrote:
On 3/30/23 00:33, y86-dev@xxxxxxxxxxxxxx wrote:
From: Benno Lossin <y86-dev@xxxxxxxxxxxxxx>
The `stack_pin_init!` macro allows pin-initializing a value on the
stack. It accepts a `impl PinInit<T, E>` to initialize a `T`. It allows
propagating any errors via `?` or handling it normally via `match`.
Signed-off-by: Benno Lossin <y86-dev@xxxxxxxxxxxxxx>
Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
---
+#[macro_export]
+macro_rules! stack_pin_init {
+ (let $var:ident $(: $t:ty)? = $val:expr) => {
+ let mut $var = $crate::init::__internal::StackInit$(::<$t>)?::uninit();
+ let mut $var = {
+ let val = $val;
+ unsafe { $crate::init::__internal::StackInit::init(&mut $var, val) }
+ };
+ };
+ (let $var:ident $(: $t:ty)? =? $val:expr) => {
+ let mut $var = $crate::init::__internal::StackInit$(::<$t>)?::uninit();
+ let mut $var = {
+ let val = $val;
+ unsafe { $crate::init::__internal::StackInit::init(&mut $var, val)? }
+ };
+ };
+}
This will be inconvenient to use if the initializer is infallible and is
used inside an infallible function. However, I'm not sure what a better
alternative would be. Perhaps we should have three variants?
That could be an option, any ideas for the syntax though? Or should it
be a different macro like `stack_pin_init!` and `try_stack_pin_init!`?
Also, maybe a `<-` rather than `=` would be more consistent?
That is sadly not possible, since `<-` is not allowed after `ty` fragments.
Anyway, I don't think this should block the PR. We can revisit it later
if it becomes a problem.
Sure.
--
Cheers,
Benno