Ship a 1.0 release

[thejpster]

Part of rust-embedded/wg#383

Blockers:

• remove const-fn now it's in Rust
• specify our MSRV
• Review and merge Use CriticalSection<'cs> instead of &'cs CriticalSection. #20 to fix Inefficiency in the CriticalSection API #7
• Review against https://rust-lang.github.io/api-guidelines/ – happening in Pre-1.0 API Guidelines Audit #26
• Mutex is not safe on multi-core systems - Mutex is not safe on multi-core systems #12
• Should Peripheral be removed?
• What to do with the Nr trait? (it's gone)

[jonas-schievink]

Some simple improvements to be made before 1.0:

• Remove the const-fn feature, and the build.rs logic related to const fn support
• Review and merge Use CriticalSection<'cs> instead of &'cs CriticalSection. #20 to fix Inefficiency in the CriticalSection API #7

Other blockers:

• Resolve Mutex is not safe on multi-core systems #12 via a sound {bare_metal,cortex_m,etc}::Mutex wg#388 or Address Multi-Core Soundness by abolishing Send and Sync wg#419

Unresolved questions:

• Where is bare_metal::Peripheral used? Does it pull its weight? Needs more documentation.
• Same goes for bare_metal::Nr. Would it be better to move it outside this crate? Also: Why return u8? It should probably be renamed to something like Interrupt, since it's not a trait for numbers.

[rubberduck203]

As soon as I find the markdown version of the API checklist, I’m going to create a tracking issue for that work so items can be checked off as they’re reviewed.

[rubberduck203]

Found it. Will open the tracking issue when time allows. https://github.com/rust-lang/api-guidelines/blob/master/src/checklist.md

[therealprof]

As agreed in the 2020-03-10 meeting we're taking off the Mutex from the 1.0 blocker list. We're aiming to have the new Mutex based on mutex-trait implemented by the arch crates instead.

[luojia65]

Maybe Nr can be used as a parameter to configure vendor specific interrupt controller. However in this way Nr::nr should not always return a u8 (there could be more than 256 interrupts). It could be necessary to provide as Nr { type Id; fn nr(&self) -> Self::Id } (still working on it to adapt to Bumblebee's ECLIC controller)

[jonas-schievink]

IMO Nr logically belongs in architecture-specific core crates like cortex-m or cortex-m-rt.

We should check what uses it, and whether the users would see any benefit of having a traits that's shared between architectures. Maybe come up with potential use cases.

(EDIT: #32 deleted it)

[thejpster]

Ticked MSRV, as it's in the README.

[adamgreig]

Closed by #35.