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.
refactor to remove trans::adt and make rustc::ty::layout authoritative
I asked on IRC about optimizing struct layout by reordering fields from most-aligned to least-aligned and somehow ended up getting talked into doing this. The goal here is to make `layout` authoritative and to remove `adt`. The former has been accomplished by reimplementing `represent_type_uncached` and the latter is in progress. @eddyb thought I should make the PR now.
My plan is to reserve the actual optimization for a second PR, as this work is useful by itself.
rustbuild: Nicer error for host builds of targets
If a triple is configured only as a target, not a host, then trying to build
that triple with host artifacts would cause a panic. Fail a little nicer
instead.
Closes#36268
The src/libstd/sys/unix/net.rs file depends on it. It is missing
from Haiku. This workaround should actually 'fix' the problem,
but it turns out the fds-are-cloexec.rs test hangs. I do not
know how related these two issues are, but it warrants further
investigation.
The test is ignored on this platform for now.
* Hand rebased from Niels original work on 1.9.0
Skip binary tidy check when on Windows Linux Subsystem
While it's possible that other linux systems will include "Microsoft" in
their /proc/version, this is deemed unlikely, and since this is a tidy
check, will likely be caught by buildbot/travis either way.
Fixes#36706.
While reading this, the comment made it difficult for me to simply absorb the concept. It interrupted my reading flow, and I think this expresses the same meaning, but reads a bit better.
While it's possible that other linux systems will include "Microsoft" in
their /proc/version, this is deemed unlikely, and since this is a tidy
check, will likely be caught by buildbot/travis either way.
s390x's C ABI ty_align and ty_size are not moved because the
implementation of ty_align varies in an atypical pattern: it calls
ty_size for the llvm::Vector type kind. ty_size then cannot be moved
since it indirectly calls ty_align through align.
[breaking-change] Remove TypedArena::with_capacity
This is a follow-up to #36592.
The function is unused by rustc. Also, it doesn't really follow the
usual meaning of a `with_capacity` function because the first chunk
allocation is now delayed until the first `alloc` call.
This change reduces the size of `TypedArena` by one `usize`.
@eddyb: we discussed this on IRC. Would you like to review it?
