more evocative examples for `Sub` and `SubAssign`
These examples are exactly analogous to those in PRs #35709 and #35806. I'll probably remove the `fn main` wrappers for `Add` and `Sub` once this is merged in.
Part of #29365.
r? @steveklabnik
The memrchr fallback did not compute the offset correctly. It was
intentioned to land on usize-aligned addresses but did not.
This was suspected to resulted in a crash on ARMv7 platform!
This bug affected non-linux platforms.
I think like this, if we have a slice with pointer `ptr` and length
`len`, we want to find the last usize-aligned offset in the slice.
The correct computation should be:
For example if ptr = 1 and len = 6, and size_of::<usize>() is 4:
[ x x x x x x ]
1 2 3 4 5 6
^-- last aligned address at offset 3 from the start.
The last aligned address is ptr + len - (ptr + len) % usize_size.
Compute offset from the start as:
offset = len - (ptr + len) % usize_size = 6 - (1 + 6) % 4 = 6 - 3 = 3.
I believe the function's return value was always correct previously, if
the platform supported unaligned addresses.
Make version check in gdb_rust_pretty_printing.py more compatible.
Some versions of Python don't support the `major` field on the object returned by `sys.version_info`.
Fixes#35724
r? @brson
r? @steveklabnik
add examples that lift `<<` and `>>` to a trivial struct
replace `Scalar` structs with struct tuples
add `fn main` wrappers to enable Rust Playground "Run" button
...there is still one confusing thing – see the _BAZ functions, which
appear to be elided in the `compile-fail` test and defaulted in the
´run-pass` test (if you uncomment line 73).
compute and cache HIR hashes at beginning
This avoids the compile-time overhead of computing them twice. It also fixes
an issue where the hash computed after typeck is differen than the hash before,
because typeck mutates the def-map in place.
Fixes#35549.
Fixes#35593.
Some performance measurements suggest this `HashesMap` is very small in memory (unobservable via `-Z time-passes`) and very cheap to construct. I do see some (very minor) performance wins in the incremental case after the first run -- the first run costs more because loading the dep-graph didn't have any hashing to do in that case. Example timings from two runs of `libsyntex-syntax` -- the (1) indicates first run, (2) indicates second run, and (*) indicates both together:
| Phase | Master | Branch |
| ---- | ---- | ---- |
| compute_hashes_map (1) | N/A | 0.343 |
| load_dep_graph (1) | 0 | 0 |
| serialize dep graph (1) | 4.190 | 3.920 |
| total (1) | 4.190 | 4.260 |
| compute_hashes_map (2) | N/A | 0.344 |
| load_dep_graph (2) | 0.592 | 0.252 |
| serialize dep graph (2) | 4.119 | 3.779 |
| total (2) | 4.71 | 4.375 |
| total (*) | 8.9 | 8.635 |
r? @michaelwoerister
I can think of a few things we may want to accomplish with the documentation of the `Fn`, `FnMut`, and `FnOnce` traits:
- the relationship between these traits and the closures that implement them
- examples of non-closure implementations
- the relationship between these traits and Rust's ownership semantics
add module-level documentation for `Fn*` traits
Describe how `Fn*` traits, closure types, and ownership semantics are
linked, and provide examples of higher-level functions that take `Fn*`s.
more examples for `Fn*` traits
create correct (though not yet elegant) examples for `FnMut` and `FnOnce`
add trait links to module-level documentation
third time's a charm!
argument -> capture for trait documentation
This wording will need to be supported with better examples for
capturing eventually.
correct `FnOnce` example
I also fixed some of the trait wording here to make the concept of
capturing clearer; though that still needs more work.
replace `x + x` with `x * 2` for `fn double`
Implement 1581 (FusedIterator)
* [ ] Implement on patterns. See https://github.com/rust-lang/rust/issues/27721#issuecomment-239638642.
* [ ] Handle OS Iterators. A bunch of iterators (`Args`, `Env`, etc.) in libstd wrap platform specific iterators. The current ones all appear to be well-behaved but can we assume that future ones will be?
* [ ] Does someone want to audit this? On first glance, all of the iterators on which I implemented `FusedIterator` appear to be well-behaved but there are a *lot* of them so a second pair of eyes would be nice.
* I haven't touched rustc internal iterators (or the internal rand) because rustc doesn't actually call `fuse()`.
* `FusedIterator` can't be implemented on `std::io::{Bytes, Chars}`.
Closes: #35602 (Tracking Issue)
Implements: rust-lang/rfcs#1581
Implement `CoerceUnsized` for `{Cell, RefCell, UnsafeCell}`
These impls are analogous to the one for `NonZero`. It's occasionally useful to be able to coerce the cell types when they're being used inside another abstraction. See Manishearth/rust-gc#17 for an example.
r? @eddyb
