268: Expose proc macro docs via the main crate r=nikomatsakis a=1tgr
Improve visibility by placing the `database` and `query_group` proc macros at the bottom of the main docs page, instead of manually browsing to the docs for the `salsa-macros` crate.
Co-authored-by: Tim Robinson <tim.g.robinson@gmail.com>
The primary motivation here is reducing dependencies. rand has quite a
few of them, and many come from `getrandom` crate (bindings to system
APIs to get true randomness). Some of `getrandom` crates don't have
Apache 2.0 OR MIT license, and it probably doesn't make sense to make
salsa's licensing situation more complicated for feature we don't even
use.
There's a number of small&fast random crates there:
* randomize
* oorandom
* fastrand
I've picked oorandom because it was the simplest & smallest (doesn't
have a thread_local RNG, for example).
This had two unexpected consequences, one unfortunate, one "medium":
* All `salsa::Database` must be `'static`. This falls out from
`Q::DynDb` not having access to any lifetimes, but also the defaulting
rules for `dyn QueryGroup` that make it `dyn QueryGroup + 'static`. We
don't really support generic databases anyway yet so this isn't a big
deal, and we can add workarounds later (ideally via GATs).
* It is now statically impossible to invoke `snapshot` from a query,
and so we don't need to test that it panics. This is because the
signature of `snapshot` returns a `Snapshot<Self>` and that is not
accessible to a `dyn QueryGroup` type. Similarly, invoking
`Runtime::snapshot` directly is not possible becaues it is
crate-private. So I removed the test. This seems ok, but eventually I
would like to expose ways for queries to do parallel
execution (matklad and I had talked about a "speculation" primitive
for enabling that).
* This commit is 99% boilerplate I did with search-and-replace. I also
rolled in a few other changes I might have preferred to factor out,
most notably removing the `GetQueryTable` plumbing trait in favor of
free-methods, but it was awkward to factor them out and get all the
generics right (so much simpler in this version).
