Primarily affects the MIR construction, which indirectly improves LLVM
IR generation, but some LLVM IR changes have been made too.
* Handle "statement expressions" more intelligently. These are
expressions that always evaluate to `()`. Previously a temporary would
be generated as a destination to translate into, which is unnecessary.
This affects assignment, augmented assignment, `return`, `break` and
`continue`.
* Avoid inserting drops for non-drop types in more places. Scheduled
drops were already skipped for types that we knew wouldn't need
dropping at construction time. However manually-inserted drops like
those for `x` in `x = y;` were still generated. `build_drop` now takes
a type parameter like its `schedule_drop` counterpart and checks to
see if the type needs dropping.
* Avoid generating an extra temporary for an assignment where the types
involved don't need dropping. Previously an expression like
`a = b + 1;` would result in a temporary for `b + 1`. This is so the
RHS can be evaluated, then the LHS evaluated and dropped and have
everything work correctly. However, this isn't necessary if the `LHS`
doesn't need a drop, as we can just overwrite the existing value.
* Improves lvalue analysis to allow treating an `Rvalue::Use` as an
operand in certain conditions. The reason for it never being an
operand is so it can be zeroed/drop-filled, but this is only true for
types that need dropping.
The first two changes result in significantly fewer MIR blocks being
generated, as previously almost every statement would end up generating
a new block due to the drop of the `()` temporary being generated.
Make some fatal lexer errors recoverable
I've kept the changes to a minimum since I'm not really sure if this approach is a acceptable.
fixes#12834
cc @nrc
report `const_err` on all expressions that can fail
also a drive-by fix for reporting an "overflow in shift *left*" when shifting an `i64` *right*
This increases the warning noise for shifting by more than the bitwidth and for `-T::MIN`. I can silence the bitwidth warnings explicitly and fix the const evaluator to make sure `--$expr` is treated exactly like `$expr` (which is kinda wrong, but mathematically right).
r? @eddyb
special-case #[derive(Copy, Clone)] with a shallow clone
If a type is Copy then its Clone implementation can be a no-op. Currently `#[derive(Clone)]` generates a deep clone anyway. This can lead to lots of code bloat.
This PR detects the case where Copy and Clone are both being derived (the general case of "is this type Copy" can't be determined by a syntax extension) and generates the shallow Clone impl. Right now this can only be done if there are no type parameters (see https://github.com/rust-lang/rust/issues/31085#issuecomment-178988663), but this restriction can be removed after specialization.
Fixes#31085.
rustdoc: Handle concurrent mkdir requests
It's likely that `rustdoc` as a tool is run concurrently in the same output
(e.g. documenting multiple crates as Cargo does), in which case it needs to
handle concurrent calls to `fs::create_dir`.
Changes #[derive(Copy, Clone)] to use a faster impl of Clone when
both derives are present, and there are no generics in the type.
The faster impl is simply returning *self (which works because the
type is also Copy). See the comments in libsyntax_ext/deriving/clone.rs
for more details.
There are a few types which are Copy but not Clone, in violation
of the definition of Copy. These include large arrays and tuples. The
very existence of these types is arguably a bug, but in order for this
optimization not to change the applicability of #[derive(Copy, Clone)],
the faster Clone impl also injects calls to a new function,
core::clone::assert_receiver_is_clone, to verify that all members are
actually Clone.
This is not a breaking change, because pursuant to RFC 1521, any type
that implements Copy should not do any observable work in its Clone
impl.
Normalize types before using them in debuginfo.
Small oversight, fixes#33096 - odd thing is that the old code doesn't look like it should've ever worked, although it wasn't using all of the type parameters, so maybe that's what changed.
mk: Fix use of deprecated configure var
The `--android-cross-path` has been deprecated for some time now, we should use
`CFG_ARM_LINUX_ANDROIDEABI_NDK` instead.
Ideally this would use the right triple, but we're only testing ARM for now.
The `--android-cross-path` has been deprecated for some time now, we should use
`CFG_ARM_LINUX_ANDROIDEABI_NDK` instead.
Ideally this would use the right triple, but we're only testing ARM for now.
clarify documentation of TcpStream::connect() for multiple valid addresses
I am not sure how the UDP part of the stdlib behaves when passing multiple valid addresses, but it should be mentioned as there are legit use cases for [`impl<'a> ToSocketAddrs for &'a [SocketAddr]`](http://doc.rust-lang.org/nightly/std/net/trait.ToSocketAddrs.html), a TCP fallback only being one.
Just a little example program for anyone willing to enhance the documentation further:
```rust
use std::net::SocketAddr;
use std::net::ToSocketAddrs;
use std::net::TcpStream;
fn main()
{
let v: Vec<SocketAddr> = vec!
[
"127.0.0.1:1338".to_socket_addrs().unwrap().next().unwrap(),
"127.0.0.1:1337".to_socket_addrs().unwrap().next().unwrap(),
"127.0.0.1:1339".to_socket_addrs().unwrap().next().unwrap(),
];
let stream = TcpStream::connect(&v[..]).unwrap();
}
```
rustdoc: inline all the impls
This used to be done to avoid inlining impls referencing private items, but is now unnecessary since we actually check that impls do not reference non-doc-reachable items.
fixes#32881fixes#33025fixes#33113
r? @alexcrichton
Enable vfp3-d16 for ARMv7 Android target
Android's [armeabi-v7a ABI][1] guarantees at least VFPv3-d16 hardware FPU support, so Rust should include this in the default features for the `arm-linux-androideabi` target.
[1]: https://developer.android.com/ndk/guides/abis.html
Suppress fallback and ambiguity errors
If the infcx has observed other errors, then suppress both default type
parameter fallback (which can be unreliable, as the full constraint set
is not available) and errors related to unresovled
variables (annoyingly, integer type variables cannot currently be
unified with error, so that has to be a separate mechanism). Also add a
flag to `infcx` to allow us to independently indicate when we have
observed an error and hence should trigger this suppression mode.
Fixes#31997
cc @alexcrichton
r? @arielb1
It's likely that `rustdoc` as a tool is run concurrently in the same output
(e.g. documenting multiple crates as Cargo does), in which case it needs to
handle concurrent calls to `fs::create_dir`.
Make the `Iterator::enumerate` doc example more clear
The example uses integers for the value being iterated over, but the indices
added by `enumerate` are also integers, so I always end up double taking and
thinking harder than I should when parsing the documentation. I also always
forget which order the index and value are in the tuple so I frequently hit this
stumbling block. This commit changes the documentation to iterate over
characters so that it is immediately obvious which part of the tuple is the
index and which is the value.
