Clean up hasher discussion on HashMap
* We never want to make guarantees about protecting against attacks.
* "True randomness" is not the right terminology to be using in this
context.
* There is significantly more nuance to the performance of SipHash than
"somewhat slow".
r? @steveklabnik
Follow up to discussion on #35371
Change encode_utf{8,16}() to write to a buffer and panic if it's too small
cc #27784
Should the "A buffer that's too small" examples be removed and replaced by tests?
Remove CString drop test.
The test relies on the undefined behavior, and so may fail in some
circumstances. This can be worked around by stubbing a memory allocator
in the test, but it is a bit of work, and LLVM could still theoretically
eliminate the write of the zero byte in release mode (which is
intended).
So let's just remove the test and mark the function as inline. It
shouldn't be optimized away when inlined into the debug build of user's
code.
Supersedes #36607
r? @alexcrichton
When getaddrinfo returns EAI_SYSTEM retrieve actual error from errno.
Fixes issue #36546. This change also updates libc to earliest version
that includes EAI_SYSTEM constant.
Previously, in cases where `EAI_SYSTEM` has been returned from getaddrinfo, the
resulting `io::Error` would be broadly described as "System error":
Error { repr: Custom(Custom { kind: Other, error: StringError("failed to lookup address information: System error") }) }
After change a more detailed error is crated based on particular value of
errno, for example:
Error { repr: Os { code: 64, message: "Machine is not on the network" } }
The only downside is that the prefix "failed to lookup address information" is
no longer included in the error message.
Haiku: Initial work at OS support
These changes should be non-invasive to non-Haiku platforms. These patches were hand reworked from Neil's original Rust 1.9.0 patches. I've done some style cleanup and design updates along the way.
There are a few small additional patches to libc, rust-installer and compiler-rt that will be submitted once this one is accepted.
Haiku can be compiled on Linux, and a full gcc cross-compiler with a Haiku target is available, which means bootstrapping should be fairly easy. The patches here have already successfully bootstrapped under our haiku x86_gcc2 architecture. http://rust-on-haiku.com/wiki/PortingRust
I'll be focusing on our more modern gcc5 x86 and x86 architectures for now.
As for support, we're not seeking official support for now. We understand Haiku isn't a top-tier OS choice, however having these patches upstream greatly reduces the amount of patchwork we have to do. Mesa has Haiku code upstream, and we submit patches to keep it going. Mesa doesn't test on Haiku and we're ok with that :-)
The test relies on the undefined behavior, and so may fail in some
circumstances. This can be worked around by stubbing a memory allocator
in the test, but it is a bit of work, and LLVM could still theoretically
eliminate the write of the zero byte in release mode (which is
intended).
So let's just remove the test and mark the function as inline. It
shouldn't be optimized away when inlined into the debug build of user's
code.
Don't allocate during default HashSet creation.
The following `HashMap` creation functions don't allocate heap storage for elements.
```
HashMap::new()
HashMap::default()
HashMap::with_hasher()
```
This is good, because it's surprisingly common to create a HashMap and never
use it. So that case should be cheap.
However, `HashSet` does not have the same behaviour. The corresponding creation
functions *do* allocate heap storage for the default number of non-zero
elements (which is 32 slots for 29 elements).
```
HashMap::new()
HashMap::default()
HashMap::with_hasher()
```
This commit gives `HashSet` the same behaviour as `HashMap`, by simply calling
the corresponding `HashMap` functions (something `HashSet` already does for
`with_capacity` and `with_capacity_and_hasher`). It also reformats one existing
`HashSet` construction to use a consistent single-line format.
This speeds up rustc itself by 1.01--1.04x on most of the non-tiny
rustc-benchmarks.
The following `HashMap` creation functions don't allocate heap storage for elements.
```
HashMap::new()
HashMap::default()
HashMap::with_hasher()
```
This is good, because it's surprisingly common to create a HashMap and never
use it. So that case should be cheap.
However, `HashSet` does not have the same behaviour. The corresponding creation
functions *do* allocate heap storage for the default number of non-zero
elements (which is 32 slots for 29 elements).
```
HashMap::new()
HashMap::default()
HashMap::with_hasher()
```
This commit gives `HashSet` the same behaviour as `HashMap`, by simply calling
the corresponding `HashMap` functions (something `HashSet` already does for
`with_capacity` and `with_capacity_and_hasher`). It also reformats one existing
`HashSet` construction to use a consistent single-line format.
This speeds up rustc itself by 1.01--1.04x on most of the non-tiny
rustc-benchmarks.
Fix outdated Doc Comment on BufReader::seek
A long time ago non-panicking `unwrap` methods were renamed to `into_inner` in this Pull Request: https://github.com/rust-lang/rust/pull/19149
Looks like this doc comment was not updated however.
A long time ago non-panicking `unwrap` methods were renamed to `into_inner` in this Pull Request: https://github.com/rust-lang/rust/pull/19149
Looks like this doc comment was not updated however.
* We never want to make guarantees about protecting against attacks.
* "True randomness" is not the right terminology to be using in this
context.
* There is significantly more nuance to the performance of SipHash than
"somewhat slow".
