remove useless ?s (clippy::needless_question_marks)
Example code:
```rust
fn opts() -> Option<String> {
let s: Option<String> = Some(String::new());
Some(s?) // this can just be "s"
}
```
make `suggest_setup` help messages better
When I first built the compiler and didn't create a `config.toml.example`, the following was emitted:
```
help: consider running `x.py setup` or copying `config.toml.example`
```
I ran `x.py setup` but got an error so in this PR I made the help messages a little clearer.
Use !Sync std::lazy::OnceCell in usefulness checking
The `rustc_data_structures::sync::OnceCell` is thread-safe when building
a parallel compiler. This is unnecessary for the purposes of pattern
usefulness checking. Use `!Sync` `std::lazy::OnceCell` instead.
Add diagnostics for specific cases for const/type mismatch err
For now, this adds at least more information so better diagnostics can be emitted for const mismatch errors.
I'm not sure what exactly we want to emit, so I've left notes there temporarily, also to see if this is the right approach
r? ```@lcnr```
cc: ```@estebank```
Implement RFC 2580: Pointer metadata & VTable
RFC: https://github.com/rust-lang/rfcs/pull/2580
~~Before merging this PR:~~
* [x] Wait for the end of the RFC’s [FCP to merge](https://github.com/rust-lang/rfcs/pull/2580#issuecomment-759145278).
* [x] Open a tracking issue: https://github.com/rust-lang/rust/issues/81513
* [x] Update `#[unstable]` attributes in the PR with the tracking issue number
----
This PR extends the language with a new lang item for the `Pointee` trait which is special-cased in trait resolution to implement it for all types. Even in generic contexts, parameters can be assumed to implement it without a corresponding bound.
For this I mostly imitated what the compiler was already doing for the `DiscriminantKind` trait. I’m very unfamiliar with compiler internals, so careful review is appreciated.
This PR also extends the standard library with new unstable APIs in `core::ptr` and `std::ptr`:
```rust
pub trait Pointee {
/// One of `()`, `usize`, or `DynMetadata<dyn SomeTrait>`
type Metadata: Copy + Send + Sync + Ord + Hash + Unpin;
}
pub trait Thin = Pointee<Metadata = ()>;
pub const fn metadata<T: ?Sized>(ptr: *const T) -> <T as Pointee>::Metadata {}
pub const fn from_raw_parts<T: ?Sized>(*const (), <T as Pointee>::Metadata) -> *const T {}
pub const fn from_raw_parts_mut<T: ?Sized>(*mut (),<T as Pointee>::Metadata) -> *mut T {}
impl<T: ?Sized> NonNull<T> {
pub const fn from_raw_parts(NonNull<()>, <T as Pointee>::Metadata) -> NonNull<T> {}
/// Convenience for `(ptr.cast(), metadata(ptr))`
pub const fn to_raw_parts(self) -> (NonNull<()>, <T as Pointee>::Metadata) {}
}
impl<T: ?Sized> *const T {
pub const fn to_raw_parts(self) -> (*const (), <T as Pointee>::Metadata) {}
}
impl<T: ?Sized> *mut T {
pub const fn to_raw_parts(self) -> (*mut (), <T as Pointee>::Metadata) {}
}
/// `<dyn SomeTrait as Pointee>::Metadata == DynMetadata<dyn SomeTrait>`
pub struct DynMetadata<Dyn: ?Sized> {
// Private pointer to vtable
}
impl<Dyn: ?Sized> DynMetadata<Dyn> {
pub fn size_of(self) -> usize {}
pub fn align_of(self) -> usize {}
pub fn layout(self) -> crate::alloc::Layout {}
}
unsafe impl<Dyn: ?Sized> Send for DynMetadata<Dyn> {}
unsafe impl<Dyn: ?Sized> Sync for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Debug for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Unpin for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Copy for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Clone for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Eq for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> PartialEq for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Ord for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> PartialOrd for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Hash for DynMetadata<Dyn> {}
```
API differences from the RFC, in areas noted as unresolved questions in the RFC:
* Module-level functions instead of associated `from_raw_parts` functions on `*const T` and `*mut T`, following the precedent of `null`, `slice_from_raw_parts`, etc.
* Added `to_raw_parts`
Implement reborrow for closure captures
The strategy for captures is detailed here with examples: https://hackmd.io/PzxYMPY4RF-B9iH9uj9GTA
Key points:
- We only need to reborrow a capture in case of move closures.
- If we mutate something via a `&mut` we store it as a `MutBorrow`/`UniqueMuBorrow` of the path containing the `&mut`,
- Similarly, if it's read via `&` ref we just store it as a `ImmBorrow` of the path containing the `&` ref.
- If a path doesn't deref a `&mut`, `&`, then that path is captured by Move.
- If the use of a path results in a move when the closure is called, then that path is truncated before any deref and the truncated path is moved into the closure.
- In the case of non-move closure if a use of a path results in a move, then the path is truncated before any deref and the truncated path is moved into the closure.
Note that the implementation differs a bit from the document to allow for truncated path to be used in the ClosureKind analysis that happens as part of the first capture analysis pass.
Closes: https://github.com/rust-lang/project-rfc-2229/issues/31
r? ````@nikomatsakis````
Placeholder lifetime error cleanup
- Remove note of trait definition
- Avoid repeating the same self type
- Use original region names when possible
- Use this error kind more often
- Print closure signatures when they are suppose to implement `Fn*` traits
Works towards #57374
r? ```@nikomatsakis```
Fix debug information for function arguments of type &str or slice.
Issue details:
When lowering MIR to LLVM IR, the compiler decomposes every &str and slice argument into a data pointer and a usize. Then, the original argument is reconstructed from the pointer and the usize arguments in the body of the function that owns it. Since the original argument is declared in the body of a function, it should be marked as a LocalVariable instead of an ArgumentVairable. This confusion causes MSVC debuggers unable to visualize &str and slice arguments correctly. (See https://github.com/rust-lang/rust/issues/81894 for more details).
Fix details:
Making sure that the debug variable for every &str and slice argument is marked as LocalVariable instead of ArgumentVariable in computing_per_local_var_debug_info. This change has been verified on VS Code debugger, VS debugger, WinDbg and LLDB.
Fix SourceMap::start_point
`start_point` needs to return the *first* character's span, but it would
previously call `find_width_of_character_at_span` which returns the span
of the *last* character. The implementation is now fixed.
Other changes:
- Docs for start_point, end_point, find_width_of_character_at_span
updated
- Minor simplification in find_width_of_character_at_span code
Fixes#81800
Add a `Result::into_ok_or_err` method to extract a `T` from `Result<T, T>`
When updating code to handle the semi-recent deprecation of `compare_and_swap` in favor of `compare_exchange`, which returns `Result<T, T>`, I wanted this. I've also wanted it with code using `slice::binary_search` before.
The name (and perhaps the documentation) is the hardest part here, but this name seems consistent with the other Result methods, and equivalently memorable.
Update books
## nomicon
1 commits in bbf06ad39d1f45654047e9596b750cc6e6d1b693..adca786547d08fe676b2fc7a6f08c2ed5280ca38
2021-01-22 07:07:31 -0800 to 2021-02-16 16:34:20 +0900
- Merge pull request rust-lang-nursery/nomicon#254 from mdaverde/ml/adds-compiler-err-lifetimes
## reference
9 commits in f02b09eb6e8af340ad1256a54adb7aae2ff3163e..361367c126290ac17cb4089f8d38fd8b2ac43f98
2021-01-22 01:53:02 -0800 to 2021-02-15 09:58:13 -0800
- Define turbofish in the glossary (rust-lang-nursery/reference#964)
- Remove enum variant expr (rust-lang-nursery/reference#963)
- One sentence is one line src/expressions/* (rust-lang-nursery/reference#962)
- Referencify bool type (rust-lang-nursery/reference#940)
- Fix typo in type cast expression table (rust-lang-nursery/reference#959)
- Define rust (rust-lang-nursery/reference#953)
- Remove "Memory Ownership" chapter (rust-lang-nursery/reference#952)
- Added setting nightly as a requirement for running tests (rust-lang-nursery/reference#955)
- Refactored build steps for better readability (rust-lang-nursery/reference#936)
## book
13 commits in e724bd826580ff95df48a8533af7dec1080693d4..db5e8a5105aa22979490dce30e33b68d8645761d
2021-01-20 08:19:49 -0600 to 2021-02-12 16:58:20 -0500
- Update to Rust 1.50
- Fix issue rust-lang/book#2574 - Improve the explanation about the behaviour of `read_line`. (rust-lang/book#2575)
- closures: replace "is called" with "is defined" (rust-lang/book#2556)
- Minor clarification: types -> values in ch16-04 (rust-lang/book#2587)
- fixed hidden code listing (rust-lang/book#2610)
- Merge remote-tracking branch 'origin/pr/2604'
- (rust-lang/book#2601)
- Merge remote-tracking branch 'origin/pr/2589'
- Fix text wrapping
- Some small rewordings I noticed while rereading just now
- (rust-lang/book#2592)
- Removed 'of' between type alias in Ch 19-04. (rust-lang/book#2581)
- Merge remote-tracking branch 'origin/pr/2554'
## rust-by-example
2 commits in f633769acef68574427a6fae6c06f13bc2199573..551cc4bc8394feccea6acd21f86d9a4e1d2271a0
2021-01-13 20:58:25 -0300 to 2021-02-03 17:12:37 -0300
- remove // (rust-lang/rust-by-example#1409)
- Update arc.md (rust-lang/rust-by-example#1406)
## edition-guide
3 commits in b91a9a881ee007c12e74e844460ec407cf07a50f..1da3c411f17adb1ba5de1683bb6acee83362b54a
2020-11-02 11:02:03 -0600 to 2021-02-16 16:46:40 -0800
- Update link for no_std. (rust-lang-nursery/edition-guide#231)
- Add git link to the source. (rust-lang-nursery/edition-guide#228)
- Update musl libc link (rust-lang-nursery/edition-guide#230)
## embedded-book
1 commits in ceec19e873be87c6ee5666b030c6bb612f889a96..4cf7981696a85c3e633076c6401611bd3f6346c4
2021-01-03 13:13:10 +0000 to 2021-02-11 10:55:22 +0000
- Fix installing dateutil since it is now a dependency of the GHP import script (rust-embedded/book#282)
Document that `assert!` format arguments are evaluated lazily
It can be useful to do some computation in `assert!` format arguments, in order to get better error messages. For example:
```rust
assert!(
some_condition,
"The state is invalid. Details: {}",
expensive_call_to_get_debugging_info(),
);
```
It seems like `assert!` only evaluates the format arguments if the assertion fails, which is useful but doesn't appear to be documented anywhere. This PR documents the behavior and adds some tests.
Don't fail to remove files if they are missing
In the backend we may want to remove certain temporary files, but in
certain other situations these files might not be produced in the first
place. We don't exactly care about that, and the intent is really that
these files are gone after a certain point in the backend.
Here we unify the backend file removing calls to use `ensure_removed`
which will attempt to delete a file, but will not fail if it does not
exist (anymore).
The tradeoff to this approach is, of course, that we may miss instances
were we are attempting to remove files at wrong paths due to some bug –
compilation would silently succeed but the temporary files would remain
there somewhere.
To digit simplification
I found out the other day that all the ascii digits have the first four bits as one would hope them to. (Eg. char `2` ends `0b0010`). There are two bits to indicate it's in the digit range ( `0b0011_0000`). If it is a true digit then all the higher bits aside from these two will be 0 (as ascii is the lowest part of the unicode u32 spectrum). So XORing with `0b11_0000` should mean we either get the number 0-9 or alternativly we get a larger number in the u32 space. If we get something that's not 0-9 then it will be discarded as it will be greater than the radix.
The code seems so fast though that there's quite a lot of noise in the benchmarks so it's not that easy to prove conclusively that it's faster as well as less instructions.
The non-fast path I was toying with as well wondering if we could do this as then we'd only have one return and less instructions still:
```
match self {
'a'..='z' => self as u32 - 'a' as u32 + 10,
'A'..='Z' => self as u32 - 'A' as u32 + 10,
_ => { radix = 10; self as u32 ^ ASCII_DIGIT_MASK},
}
```
Here's the [godbolt](https://godbolt.org/z/883c9n).
( H/T to ``@byteshadow`` for pointing out xor was what I needed)
Add 'consider using' message to overflowing_literals
Fixes#79744.
Ironically, the `overflowing_literals` handler for binary or hex already
had this message! You would think it would be the other way around :)
cc ```@scottmcm```
Quotes the arg and not quotes the arg have different effect on Windows when the program called
are msys2/cygwin program.
Refer to https://github.com/msys2/MSYS2-packages/issues/2176
Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
