Add docs about performance and `Iterator::map` to `[T; N]::map`
This suboptimal code gen for some usages of array::map got a bit of
attention by multiple people throughout the community. Some cases:
- https://github.com/rust-lang/rust/issues/75243#issuecomment-866051086
- https://github.com/rust-lang/rust/issues/75243#issuecomment-874732134
- https://www.reddit.com/r/rust/comments/oeqqf7/unexpected_high_stack_usage/
My *guess* is that this gets the attention it gets because in JavaScript
(and potentially other languages), a `map` function on arrays is very
commonly used since in those languages, arrays basically take the role
of Rust's iterator. I considered explicitly naming JavaScript in the
first paragraph I added, but I couldn't find precedence of mentioning
other languages in standard library doc, so I didn't add it.
When array::map was stabilized, we still wanted to add docs, but that
somehow did not happen in time. So here we are. Not sure if this sounds
crazy but maybe it is worth considering beta backporting this? Only if
it's not a lot of work, of course! But yeah, stabilized array::map is
already in beta and if this problem is really as big as it sometimes seems,
might be worth having the docs in place when 1.55 is released.
CC ``@CryZe``
r? ``@m-ou-se`` (since you were involved in that discussion and the stabilization)
Add warning when whitespace is not skipped after an escaped newline
Fixes issue #87318, also simplifies issue #87319.
* Add support to the lexer to emit warnings as well as errors.
* Emit a warning when a string literal contains an escaped newline, but when (some of) the whitespace on the next line is not skipped due to it being non-ASCII.
Fix issue with autofix for ambiguous associated function from Rust 2021 prelude when struct is generic
Fixes#86940
The test cases and associated issue should make it clear what specifically this is meant to fix. The fix is slightly hacky in that we check against the literal source code of the call site for the presence of `<` in order to determine if the user has included the generics for the struct (meaning we don't need to include them for them).
r? ``@nikomatsakis``
Make `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` warn by default
This PR makes the `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` lint warn by default.
To avoid showing a large number of un-actionable warnings to users, we only enable the lint for macros defined in the same crate. This ensures that users will be able to fix the warning by simply removing a semicolon.
In the future, I'd like to enable this lint unconditionally, and eventually make it into a hard error in a future edition. This PR is a step towards that goal.
Use more precise span for E0282 in cast expressions
This pull request fixes#85586. The example code given there:
```rust
fn main() {
let a = [1, 2, 3].iter().sum();
let b = (a + 1) as usize;
}
```
currently produces
```
error[E0282]: type annotations needed
--> issue-85586.rs:3:13
|
3 | let b = (a + 1) as usize;
| ^^^^^^^^^^^^^^^^ cannot infer type
|
= note: type must be known at this point
error: aborting due to previous error
```
even though the type of the entire cast expression quite clearly should be `usize`. The error is in the cast's left-hand side, which is made explicit by the changes in this PR:
```
error[E0282]: type annotations needed
--> issue-85586.rs:3:13
|
3 | let b = (a + 1) as usize;
| ^^^^^^^ cannot infer type
|
= note: type must be known at this point
error: aborting due to previous error
```
Add feature gates for `for` and `?` in consts
These operations seems *relatively* straightforward to support, and only seem to be blocked on `impl const Trait`.
I have included a working test for `const_try`, but `const_for` is currently unusable without reimplementing *every single* defaulted `Iterator` method, so I didn't do that.
(both features still need tracking issues before this is merged)
Rollup of 10 pull requests
Successful merges:
- #87052 (Optimize fmt::PadAdapter::wrap)
- #87522 (Fix assert in diy_float)
- #87553 (Fix typo in rustc_driver::version)
- #87554 (2229: Discr should be read when PatKind is Range)
- #87564 (min_type_alias_impl_trait is going to be removed in 1.56)
- #87574 (Update the examples in `String` and `VecDeque::retain`)
- #87583 (Refactor compression cache in v0 symbol mangler)
- #87585 (Add missing links for core::char types)
- #87594 (fs File get_path procfs usage for netbsd same as linux.)
- #87602 ([backtraces]: look for the `begin` symbol only after seeing `end`)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
[backtraces]: look for the `begin` symbol only after seeing `end`
On `x86_64-pc-windows-msvc`, we often get backtraces which look like
this:
```
10: 0x7ff77e0e9be5 - std::panicking::rust_panic_with_hook
11: 0x7ff77e0e11b4 - std::sys_common::backtrace::__rust_begin_short_backtrace::h5769736bdb11136c
12: 0x7ff77e0e116f - std::sys_common::backtrace::__rust_end_short_backtrace::h61c7ecb1b55338ae
13: 0x7ff77e0f89dd - std::panicking::begin_panic::h8e60ef9f82a41805
14: 0x7ff77e0e108c - d
15: 0x7ff77e0e1069 - c
16: 0x7ff77e0e1059 - b
17: 0x7ff77e0e1049 - a
18: 0x7ff77e0e1039 - core::ptr::drop_in_place<std::rt::lang_start<()>::{{closure}}>::h1bfcd14d5e15ba81
19: 0x7ff77e0e1186 - std::sys_common::backtrace::__rust_begin_short_backtrace::h5769736bdb11136c
20: 0x7ff77e0e100c - std::rt::lang_start::{{closure}}::ha054184bbf9921e3
```
Notice that `__rust_begin_short_backtrace` appears on frame 11 before
`__rust_end_short_backtrace` on frame 12. This is because in typical
release binaries without debug symbols, dbghelp.dll, which we use to walk
and symbolize the stack, does not know where CGU internal functions
start or end and so the closure invoked by `__rust_end_short_backtrace`
is incorrectly described as `__rust_begin_short_backtrace` because it
happens to be near that symbol.
While that can obviously change, this has been happening quite
consistently since #75048. Since this is a very small change to the std
and the change makes sense by itself, I think this is worth doing.
This doesn't completely resolve the situation for release binaries on
Windows, since without debug symbols, the stack printed can still show
incorrect symbol names (this is why the test uses `#[no_mangle]`) but it
does slightly improve the situation in that you see the same backtrace
you would see with `RUST_BACKTRACE=full` or in a debugger (without the
uninteresting bits at the top and bottom).
Fixes part of #87481
Refactor compression cache in v0 symbol mangler
* Remove redundant option around compression caches (they are always present).
* Flatten compression caches into symbol mangler to avoid dynamic memory allocation.
* Implement printer for `&mut SymbolMangler` instead of `SymbolMangler` to avoid passing now slightly larger symbol mangler by value.
Update the examples in `String` and `VecDeque::retain`
The examples added in #60396 used a "clever" post-increment hack,
unrelated to the actual point of the examples. That hack was found
[confusing] in the users forum, and #81811 already changed the `Vec`
example to use a more direct iterator. This commit changes `String` and
`VecDeque` in the same way for consistency.
[confusing]: https://users.rust-lang.org/t/help-understand-strange-expression/62858
min_type_alias_impl_trait is going to be removed in 1.56
#87501 removed `min_type_alias_impl_trait` but meanwhile that PR was approved in homu queue, a new beta was cut so we need to bump the version because it won't be removed in 1.55.
r? ```@oli-obk```
```@bors``` rollup=always
2229: Discr should be read when PatKind is Range
This PR fixes an issue related to pattern matching in closures when Edition 2021 is enabled.
- If any of the patterns the discr is being matched on is `PatKind::Range` then the discr should be read
r? ```@nikomatsakis```
Closes https://github.com/rust-lang/rust/issues/87426
Optimize fmt::PadAdapter::wrap
After adding the first `write!` usage to my project and printing the result to the console, I noticed, that my binary contains the strings "called `Option::unwrap()` on a `None` value`" and more importantly "C:\Users\Patrick Fischer\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\fmt\builders.rs", with my release build being configured as follows:
```
[profile.release]
panic = "abort"
codegen-units = 1
strip = "symbols" # the important bit
lto = true
```
I am in a no_std environment and my custom panic handler is a simple `loop {}`. I did not expect the above information to be preserved. I heavily suspect the edited function to be the culprit. It contains the only direct use of `Option::unwrap` in the entire file and I tracked the symbols in the assembly to be used from the section `_ZN68_$LT$core..fmt..builders..PadAdapter$u20$as$u20$core..fmt..Write$GT$9write_str17ha1d5e5efe167202aE`.
Aside from me suspecting this function to be the culprit, the replaced code performs the same operation as `Option::insert`, but without the `unreachable_unchecked` optimization `Option::insert` provides. Therefore, it makes sense to me to use the more optimized version, instead.
As I don't change any semantics, I hope a simple pull request suffices.
Mir borrowck does not generate lifetime variables for 'static lifetimes during opaque type resolution
Fixes#87455
This situation was unreachable before #87287 as we used to just grab the resolved opaque type from typeck and replaced all regions with new inference vars. After #87287 we let the `InferCx` in mir borrowck figure out the opaque type all by itself (which it already did before, but it only used the result to sanity check with the typeck result).
Fix may not to appropriate might not or must not
I went through and changed occurrences of `may not` to be more explicit with `might not` and `must not`.
Improve intra doc errors display
#87169
`@jyn514` This is what I had in mind to avoid having duplicated backticks. I also gave a try to simply updating the span for the suggestion/help messages but I think this current one is better because less "noisy". Anyway, that allows you to see the result. ;)
Bufwriter disassembly tweaks
In #80690 `@BurntSushi` observed that `WriterPanicked` was erroneously not exported, and suggested renaming `into_raw_parts` to `into_parts`. (More info in my commit messages.)
r? `@BurntSushi`
On `x86_64-pc-windows-msvc`, we often get backtraces which look like
this:
```
10: 0x7ff77e0e9be5 - std::panicking::rust_panic_with_hook
11: 0x7ff77e0e11b4 - std::sys_common::backtrace::__rust_begin_short_backtrace::h5769736bdb11136c
12: 0x7ff77e0e116f - std::sys_common::backtrace::__rust_end_short_backtrace::h61c7ecb1b55338ae
13: 0x7ff77e0f89dd - std::panicking::begin_panic::h8e60ef9f82a41805
14: 0x7ff77e0e108c - d
15: 0x7ff77e0e1069 - c
16: 0x7ff77e0e1059 - b
17: 0x7ff77e0e1049 - a
18: 0x7ff77e0e1039 - core::ptr::drop_in_place<std::rt::lang_start<()>::{{closure}}>::h1bfcd14d5e15ba81
19: 0x7ff77e0e1186 - std::sys_common::backtrace::__rust_begin_short_backtrace::h5769736bdb11136c
20: 0x7ff77e0e100c - std::rt::lang_start::{{closure}}::ha054184bbf9921e3
```
Notice that `__rust_begin_short_backtrace` appears on frame 11 before
`__rust_end_short_backtrace` on frame 12. This is because in typical
release binaries without debug symbols, dbghelp.dll, which we use to walk
and symbolize the stack, does not know where CGU internal functions
start or end and so the closure invoked by `__rust_end_short_backtrace`
is incorrectly described as `__rust_begin_short_backtrace` because it
happens to be near that symbol.
While that can obviously change, this has been happening quite
consistently since #75048. Since this is a very small change to the std
and the change makes sense by itself, I think this is worth doing.
This doesn't completely resolve the situation for release binaries on
Windows, since without debug symbols, the stack printed can still show
incorrect symbol names (this is why the test uses `#[no_mangle]`) but it
does slightly improve the situation in that you see the same backtrace
you would see with `RUST_BACKTRACE=full` or in a debugger (without the
uninteresting bits at the top and bottom).
I looked in stdlib and as @BurntSushi thought, `raw` is generally
used for raw pointers, or other hazardous kinds of thing. stdlib does
not have `into_parts` apart from the one I added to `IntoInnerError`.
I did an ad-hoc search of the rustdocs for my current game project
Otter, which includes quite a large number of dependencies.
`into_parts` seems heavily used for things quite like this.
So change this name.
Suggested-by: Andrew Gallant <jamslam@gmail.com>
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
I didn't notice the submodule, which means I failed to re-export this
to make it actually-public.
Reported-by: Andrew Gallant <jamslam@gmail.com>
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
The compression caches currently don't have any dedicated functionality
that would benefit from being separated. Incorporating caches directly
into the symbol manger also avoids dynamic memory allocation.
The symbol mangler, which is often passed by value, is now slightly
larger. This aspect will be addressed by a follow-up commit.
