These two attributes are used to change the entry point into a Rust program, but
for now they're being put behind feature gates until we have a chance to think
about them a little more. The #[start] attribute specifically may have its
signature changed.
This is a breaking change to due the usage of these attributes generating errors
by default now. If your crate is using these attributes, add this to your crate
root:
#![feature(start)] // if you're using the #[start] attribute
#![feature(main)] // if you're using the #[main] attribute
cc #20064
This commit aims to stabilize the `TypeId` abstraction by moving it out of the
`intrinsics` module into the `any` module of the standard library. Specifically,
* `TypeId` is now defined at `std::any::TypeId`
* `TypeId::hash` has been removed in favor of an implementation of `Hash`.
This commit also performs a final pass over the `any` module, confirming the
following:
* `Any::get_type_id` remains unstable as *usage* of the `Any` trait will likely
never require this, and the `Any` trait does not need to be implemented for
any other types. As a result, this implementation detail can remain unstable
until associated statics are implemented.
* `Any::downcast_ref` is now stable
* `Any::downcast_mut` is now stable
* `BoxAny` remains unstable. While a direct impl on `Box<Any>` is allowed today
it does not allow downcasting of trait objects like `Box<Any + Send>` (those
returned from `Thread::join`). This is covered by #18737.
* `BoxAny::downcast` is now stable.
Closes#21033. The new strategy for parsing a field pattern is to look 1 token ahead and if it's a colon, parse as "fieldname: pat", otherwise parse the shorthand form "(box) (ref) (mut) fieldname)". The previous strategy was to parse "(ref) (mut) fieldname" then if we encounter a colon, throw an error if either "ref" or "mut" were encountered.
This commit aims to stabilize the `TypeId` abstraction by moving it out of the
`intrinsics` module into the `any` module of the standard library. Specifically,
* `TypeId` is now defined at `std::any::TypeId`
* `TypeId::hash` has been removed in favor of an implementation of `Hash`.
This commit also performs a final pass over the `any` module, confirming the
following:
* `Any::get_type_id` remains unstable as *usage* of the `Any` trait will likely
never require this, and the `Any` trait does not need to be implemented for
any other types. As a result, this implementation detail can remain unstable
until associated statics are implemented.
* `Any::downcast_ref` is now stable
* `Any::downcast_mut` is now stable
* `BoxAny` remains unstable. While a direct impl on `Box<Any>` is allowed today
it does not allow downcasting of trait objects like `Box<Any + Send>` (those
returned from `Thread::join`). This is covered by #18737.
* `BoxAny::downcast` is now stable.
This commit modifies resolve to prevent conflicts with typedef names in the same
method that conflits are prevented with enum names. This is a breaking change
due to the differing semantics in resolve, and any errors generated on behalf of
this change require that a conflicting typedef, module, or structure to be
renamed so they do not conflict.
[breaking-change]
Closes#6936
This stops the compiler ICEing on the use of SIMD types in FFI signatures. It emits correct code for LLVM intrinsics, but I am quite unsure about the ABI handling in general so I've added a new feature gate `simd_ffi` to try to ensure people don't use it without realising there's a non-trivial risk of codegen brokenness.
Closes#20043.
Loading methods from external crates was erroneously using the type's privacy
for each method instead of each method's privacy. This commit fixes that.
Closes#21202
This commit also moves privacy to its own crate because I thought that was where the bug was. Turns out it wasn't, but it helped me iterate at least!
I don't know if this handling of SIMD types is correct for the C ABI on
all platforms, so lets add an even finer feature gate than just the
`simd` one.
The `simd` one can be used with (relatively) little risk of complete
nonsense, the reason for it is that it is likely that things will
change. Using the types in FFI with an incorrect ABI will at best give
absolute nonsense results, but possibly cause serious breakage too, so
this is a step up in badness, hence a new feature gate.
These two attributes are used to change the entry point into a Rust program, but
for now they're being put behind feature gates until we have a chance to think
about them a little more. The #[start] attribute specifically may have its
signature changed.
This is a breaking change to due the usage of these attributes generating errors
by default now. If your crate is using these attributes, add this to your crate
root:
#![feature(start)] // if you're using the #[start] attribute
#![feature(main)] // if you're using the #[main] attribute
cc #20064
For a call like `foo.bar()` where the method `bar` can't be resolved,
the compiler will search for traits that have methods with name `bar` to
give a more informative error, providing a list of possibilities.
Closes#7643.
Loading methods from external crates was erroneously using the type's privacy
for each method instead of each method's privacy. This commit fixes that.
Closes#21202
If `a.method();` can't be resolved, we first look for implemented traits
globally and suggest those. If there are no such traits found, we only
then fall back to suggesting from the unfiltered list of traits.
Refactor compare_impl_method into its own file. Modify the
code to stop comparing individual parameter bounds.
Instead we now use the predicates list attached to the trait
and implementation generics. This ensures consistency even
when bounds are declared in different places (i.e on
a parameter vs. in a where clause).
For a call like `foo.bar()` where the method `bar` can't be resolved,
the compiler will search for traits that have methods with name `bar` to
give a more informative error, providing a list of possibilities.
Closes#7643.
#### Updated 1/12/2014
I updated the multi-line testcase to current but didn't modify the others. The spew code was broke by the `matches!` macro no longer working and I'm not interested in fixing the testcase.
I additionally added one testcase below.
Errors will in general look similar to below if the error is either `mismatched types` or a few other types. The rest are ignored.
---
#### Extra testcase:
```rust
pub trait Foo {
type A;
fn boo(&self) -> <Self as Foo>::A;
}
struct Bar;
impl Foo for i32 {
type A = u32;
fn boo(&self) -> u32 {
42
}
}
fn foo1<I: Foo<A=Bar>>(x: I) {
let _: Bar = x.boo();
}
fn foo2<I: Foo>(x: I) {
let _: Bar = x.boo();
}
pub fn baz(x: &Foo<A=Bar>) {
let _: Bar = x.boo();
}
pub fn main() {
let a = 42i32;
foo1(a);
baz(&a);
}
```
#### Multi-line output:
```cmd
$ ./rustc test3.rs
test3.rs:20:18: 20:25 error: mismatched types:
expected `Bar`,
found `<I as Foo>::A`
(expected struct `Bar`,
found associated type)
test3.rs:20 let _: Bar = x.boo();
^~~~~~~
test3.rs:31:5: 31:9 error: type mismatch resolving `<i32 as Foo>::A == Bar`:
expected u32,
found struct `Bar`
test3.rs:31 foo1(a);
^~~~
test3.rs:31:5: 31:9 note: required by `foo1`
test3.rs:31 foo1(a);
^~~~
test3.rs:32:9: 32:11 error: type mismatch resolving `<i32 as Foo>::A == Bar`:
expected u32,
found struct `Bar`
test3.rs:32 baz(&a);
^~
test3.rs:32:9: 32:11 note: required for the cast to the object type `Foo`
test3.rs:32 baz(&a);
^~
error: aborting due to 3 previous errors
```
---
This is a continuation of #19203 which I apparently broke by force pushing after it was closed. I'm attempting to add multi-line errors where they are largely beneficial - to help differentiate different types in compiler messages. As before, this is still a simple fix.
#### Testcase:
```rust
struct S;
fn test() -> Option<i32> {
let s: S;
s
}
fn test2() -> Option<i32> {
Ok(7) // Should be Some(7)
}
impl Iterator for S {
type Item = i32;
fn next(&mut self) -> Result<i32, i32> { Ok(7) }
}
fn main(){
test();
test2();
}
```
---
#### Single-line playpen errors:
```cmd
<anon>:6:5: 6:6 error: mismatched types: expected `core::option::Option<int>`, found `S` (expected enum core::option::Option, found struct S)
<anon>:6 s
^
<anon>:10:5: 10:10 error: mismatched types: expected `core::option::Option<int>`, found `core::result::Result<_, _>` (expected enum core::option::Option, found enum core::result::Result)
<anon>:10 Ok(7) // Should be Some(7)
^~~~~
<anon>:14:5: 14:55 error: method `next` has an incompatible type for trait: expected enum core::option::Option, found enum core::result::Result [E0053]
<anon>:14 fn next(&mut self) -> Result<uint, uint> { Ok(7) }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
error: aborting due to 3 previous errors
playpen: application terminated with error code 101
```
---
#### Multi-line errors:
```cmd
$ ./rustc test.rs
test.rs:6:5: 6:6 error: mismatched types:
expected `core::option::Option<i32>`,
found `S`
(expected enum `core::option::Option`,
found struct `S`)
test.rs:6 s
^
test.rs:10:5: 10:10 error: mismatched types:
expected `core::option::Option<i32>`,
found `core::result::Result<_, _>`
(expected enum `core::option::Option`,
found enum `core::result::Result`)
test.rs:10 Ok(7) // Should be Some(7)
^~~~~
test.rs:15:5: 15:53 error: method `next` has an incompatible type for trait: expected enum `core::option::Option`, found enum `core::result::Result` [E0053]
test.rs:15 fn next(&mut self) -> Result<i32, i32> { Ok(7) }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
error: aborting due to 3 previous errors
```
---
#### Positive notes
* Vim worked fine with it: https://github.com/rust-lang/rust/pull/19203#issuecomment-66861668
* `make check` didn't find any errors
* Fixed *backtick* placement suggested by @p1start at https://github.com/rust-lang/rust/pull/19203#issuecomment-64062052
#### Negative notes
* Didn't check Emacs support but also wasn't provided a testcase...
* Needs to be tested with macro errors but I don't have a good testcase yet
* I would like to move the `E[0053]` earlier (see https://github.com/rust-lang/rust/issues/19464#issuecomment-65334301) but I don't know how
* It might be better to indent the types slightly like so (but I don't know how):
```cmd
test.rs:6:5: 6:6 error: mismatched types:
expected `core::option::Option<int>`,
found `S`
(expected enum `core::option::Option`,
found struct `S`)
test.rs:6 s
```
* Deep whitespace indentation may be a bad idea because early wrapping will cause misalignment between lines
#### Other
* I thought that compiler flags or something else (environment variables maybe) might be required because of comments against it but now that seems too much of a burden for users and for too little gain.
* There was concern that it will make large quantities of errors difficult to distinguish but I don't find that an issue. They both look awful and multi-line errors makes the types easier to understand.
---
#### Single lined spew:
```cmd
$ rustc test2.rs
test2.rs:161:9: 170:10 error: method `next` has an incompatible type for trait: expected enum core::option::Option, found enum core::result::Result [E0053]
test2.rs:161 fn next(&mut self) -> Result<&'a str, int> {
test2.rs:162 self.curr = self.next;
test2.rs:163
test2.rs:164 if let (Some(open), Some(close)) = Parens::find_parens(self.all, self.next) {
test2.rs:165 self.next = if self.all.char_at(self.next) == '(' { close }
test2.rs:166 else { open }
...
test2.rs:164:21: 164:31 error: mismatched types: expected `core::result::Result<uint, int>`, found `core::option::Option<_>` (expected enum core::result::Result, found enum core::option::Option)
test2.rs:164 if let (Some(open), Some(close)) = Parens::find_parens(self.all, self.next) {
^~~~~~~~~~
test2.rs:164:33: 164:44 error: mismatched types: expected `core::result::Result<uint, int>`, found `core::option::Option<_>` (expected enum core::result::Result, found enum core::option::Option)
test2.rs:164 if let (Some(open), Some(close)) = Parens::find_parens(self.all, self.next) {
^~~~~~~~~~~
test2.rs:169:40: 169:76 error: mismatched types: expected `core::result::Result<&'a str, int>`, found `core::option::Option<&str>` (expected enum core::result::Result, found enum core::option::Option)
test2.rs:169 if self.curr != self.len { Some(self.all[self.curr..self.next]) } else { None }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test2.rs:169:86: 169:90 error: mismatched types: expected `core::result::Result<&'a str, int>`, found `core::option::Option<_>` (expected enum core::result::Result, found enum core::option::Option)
test2.rs:169 if self.curr != self.len { Some(self.all[self.curr..self.next]) } else { None }
^~~~
test2.rs:205:14: 205:18 error: mismatched types: expected `core::result::Result<uint, int>`, found `core::option::Option<uint>` (expected enum core::result::Result, found enum core::option::Option)
test2.rs:205 (open, close)
^~~~
test2.rs:205:20: 205:25 error: mismatched types: expected `core::result::Result<uint, int>`, found `core::option::Option<uint>` (expected enum core::result::Result, found enum core::option::Option)
test2.rs:205 (open, close)
^~~~~
test2.rs:210:21: 210:31 error: mismatched types: expected `core::result::Result<uint, int>`, found `core::option::Option<_>` (expected enum core::result::Result, found enum core::option::Option)
test2.rs:210 if let (Some(open), _) = Parens::find_parens(self.all, 0) {
^~~~~~~~~~
test2.rs:210:13: 212:28 error: mismatched types: expected `core::option::Option<&'a int>`, found `core::option::Option<&str>` (expected int, found str)
test2.rs:210 if let (Some(open), _) = Parens::find_parens(self.all, 0) {
test2.rs:211 Some(self.all[0..open])
test2.rs:212 } else { None }
test2.rs:299:48: 299:58 error: mismatched types: expected `Box<translate::Entity>`, found `collections::vec::Vec<_>` (expected box, found struct collections::vec::Vec)
test2.rs:299 pub fn new() -> Entity { Entity::Group(Vec::new()) }
^~~~~~~~~~
test2.rs:359:51: 359:58 error: type `&mut Box<translate::Entity>` does not implement any method in scope named `push`
test2.rs:359 Entity::Group(ref mut vec) => vec.push(e),
^~~~~~~
test2.rs:366:51: 366:85 error: type `&mut Box<translate::Entity>` does not implement any method in scope named `push`
test2.rs:366 Entity::Group(ref mut vec) => vec.push(Entity::Inner(s.to_string())),
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
error: aborting due to 12 previous errors
```
---
#### Multi-line spew:
```cmd
$ ./rustc test2.rs
test2.rs:161:9: 170:10 error: method `next` has an incompatible type for trait:
expected enum `core::option::Option`,
found enum `core::result::Result` [E0053]
test2.rs:161 fn next(&mut self) -> Result<&'a str, int> {
test2.rs:162 self.curr = self.next;
test2.rs:163
test2.rs:164 if let (Some(open), Some(close)) = Parens::find_parens(self.all, self.next) {
test2.rs:165 self.next = if self.all.char_at(self.next) == '(' { close }
test2.rs:166 else { open }
...
test2.rs:164:21: 164:31 error: mismatched types:
expected `core::result::Result<uint, int>`,
found `core::option::Option<_>`
(expected enum `core::result::Result`,
found enum `core::option::Option`)
test2.rs:164 if let (Some(open), Some(close)) = Parens::find_parens(self.all, self.next) {
^~~~~~~~~~
test2.rs:164:33: 164:44 error: mismatched types:
expected `core::result::Result<uint, int>`,
found `core::option::Option<_>`
(expected enum `core::result::Result`,
found enum `core::option::Option`)
test2.rs:164 if let (Some(open), Some(close)) = Parens::find_parens(self.all, self.next) {
^~~~~~~~~~~
test2.rs:169:40: 169:76 error: mismatched types:
expected `core::result::Result<&'a str, int>`,
found `core::option::Option<&str>`
(expected enum `core::result::Result`,
found enum `core::option::Option`)
test2.rs:169 if self.curr != self.len { Some(self.all[self.curr..self.next]) } else { None }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test2.rs:169:86: 169:90 error: mismatched types:
expected `core::result::Result<&'a str, int>`,
found `core::option::Option<_>`
(expected enum `core::result::Result`,
found enum `core::option::Option`)
test2.rs:169 if self.curr != self.len { Some(self.all[self.curr..self.next]) } else { None }
^~~~
test2.rs:205:14: 205:18 error: mismatched types:
expected `core::result::Result<uint, int>`,
found `core::option::Option<uint>`
(expected enum `core::result::Result`,
found enum `core::option::Option`)
test2.rs:205 (open, close)
^~~~
test2.rs:205:20: 205:25 error: mismatched types:
expected `core::result::Result<uint, int>`,
found `core::option::Option<uint>`
(expected enum `core::result::Result`,
found enum `core::option::Option`)
test2.rs:205 (open, close)
^~~~~
test2.rs:210:21: 210:31 error: mismatched types:
expected `core::result::Result<uint, int>`,
found `core::option::Option<_>`
(expected enum `core::result::Result`,
found enum `core::option::Option`)
test2.rs:210 if let (Some(open), _) = Parens::find_parens(self.all, 0) {
^~~~~~~~~~
test2.rs:210:13: 212:28 error: mismatched types:
expected `core::option::Option<&'a int>`,
found `core::option::Option<&str>`
(expected int,
found str)
test2.rs:210 if let (Some(open), _) = Parens::find_parens(self.all, 0) {
test2.rs:211 Some(self.all[0..open])
test2.rs:212 } else { None }
test2.rs:229:57: 229:96 error: the trait `core::ops::Fn<(char,), bool>` is not implemented for the type `|char| -> bool`
test2.rs:229 .map(|s| s.trim_chars(|c: char| c.is_whitespace()))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test2.rs:238:46: 239:75 error: type `core::str::CharSplits<'_, |char| -> bool>` does not implement any method in scope named `filter_map`
test2.rs:238 .filter_map(|s| if !s.is_empty() { Some(s.trim_chars('\'')) }
test2.rs:239 else { None })
test2.rs:237:46: 237:91 error: the trait `core::ops::Fn<(char,), bool>` is not implemented for the type `|char| -> bool`
test2.rs:237 let vec: Vec<&str> = value[].split(|c: char| matches!(c, '(' | ')' | ','))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test2.rs:238:65: 238:77 error: the type of this value must be known in this context
test2.rs:238 .filter_map(|s| if !s.is_empty() { Some(s.trim_chars('\'')) }
^~~~~~~~~~~~
test2.rs:299:48: 299:58 error: mismatched types:
expected `Box<translate::Entity>`,
found `collections::vec::Vec<_>`
(expected box,
found struct `collections::vec::Vec`)
test2.rs:299 pub fn new() -> Entity { Entity::Group(Vec::new()) }
^~~~~~~~~~
test2.rs:321:36: 322:65 error: type `core::str::CharSplits<'_, |char| -> bool>` does not implement any method in scope named `filter_map`
test2.rs:321 .filter_map(|s| if !s.is_empty() { Some(s.trim_chars('\'')) }
test2.rs:322 else { None })
test2.rs:320:36: 320:81 error: the trait `core::ops::Fn<(char,), bool>` is not implemented for the type `|char| -> bool`
test2.rs:320 let vec: Vec<&str> = s.split(|c: char| matches!(c, '(' | ')' | ','))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test2.rs:321:55: 321:67 error: the type of this value must be known in this context
test2.rs:321 .filter_map(|s| if !s.is_empty() { Some(s.trim_chars('\'')) }
^~~~~~~~~~~~
test2.rs:359:51: 359:58 error: type `&mut Box<translate::Entity>` does not implement any method in scope named `push`
test2.rs:359 Entity::Group(ref mut vec) => vec.push(e),
^~~~~~~
test2.rs:366:51: 366:85 error: type `&mut Box<translate::Entity>` does not implement any method in scope named `push`
test2.rs:366 Entity::Group(ref mut vec) => vec.push(Entity::Inner(s.to_string())),
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
error: aborting due to 24 previous errors
```
Closes#18946#19464
cc @P1start @jakub- @tomjakubowski @kballard @chris-morgan
