Most of the standard distribution is still using ~[] instead of Vec, so this
lint is essentially useless currently. When the standard distribution has been
ported to not use ~[], then we can turn the lint back on.
`Share` implies that all *reachable* content is *threadsafe*.
Threadsafe is defined as "exposing no operation that permits a data race if multiple threads have access to a &T pointer simultaneously". (NB: the type system should guarantee that if you have access to memory via a &T pointer, the only other way to gain access to that memory is through another &T pointer)...
Fixes#11781
cc #12577
What this PR will do
================
- [x] Add Share kind and
- [x] Replace usages of Freeze with Share in bounds.
- [x] Add Unsafe<T> #12577
- [x] Forbid taking the address of a immutable static item with `Unsafe<T>` interior
What's left to do in a separate PR (after the snapshot)?
===========================================
- Remove `Freeze` completely
this comes from a discussion on IRC where the split between stdin and stdout
seemed unnatural, and the fact that reading on stdin won't flush stdout, which
is unlike every other language (including C's stdio).
These variants occur rarely but inflate the whole enum for the other variants, leaving a lot of wasted space. In total this reduces `ty::sty` from 160 bytes to 96 (on a 64-bit platform).
After this, `ty_struct` and `ty_enum` are the largest variants, with the 80-byte `substs` being the major contributor.
This fixes struct passing abi on x86 ffi: Structs are now passed
indirectly with byval attribute (as clang does).
Empty structs are also explicitly ignored rather than directly passed.
Fixes#5744Fixes#11198Fixes#11343
This reduces the size of sty from 112 to 96; like with the ty_trait
variant, this variant of sty occurs rarely (~1%) so the benefits are
large and the costs small.
This reduces ty::sty from 160 bytes to just 112, and some measurements
eddyb made suggest that the ty_trait variant occurs very
rarely (e.g. ~1% of all sty instances) hence this will result in a large
memory saving, and the cost of the indirection is unlikely to be an
issue.
This adds lots of docs to the atomics module. Two of the examples
are using the future atomics API (relying on `Share`) and are ignored temporarily.
I discovered a bug in the way AtomicBool's fetch_nand method is
implemented and fixed it by using the correct value for `true`.
I also fixed the implementation of AcqRel fences (it was only doing
a release barrier), and made a "relaxed" fence a failure.
possible by also calling `clone_from` on it.
In general, `Clone` implementors that overwrite `clone_from`
should try to to use it recursivly for substructures.
A major discoverability issue with rustdoc is that all crates have their
documentation built in isolation, so it's difficult when looking at the
documentation for libstd to learn that there's a libcollections crate with a
HashMap in it.
This commit moves rustdoc a little closer to improving the multiple crate
experience. This unifies all search indexes for all crates into one file so all
pages share the same search index. This allows searching to work across crates
in the same documentation directory (as the standard distribution is currently
built).
This strategy involves updating a shared file amongst many rustdoc processes, so
I implemented a simple file locking API for handling synchronization for updates
to the shared files.
cc #12554
