By returning the passed value black_box can be used on data being
passed to a function being benchmarked. This ensures the compiler
does not optimize the function for the input which could result in
the entire function being optimized away.
It's passed to the underlying reader, so uninitialized memory == sad
times.
We might want to shrink the default buffer size as well. 64k is pretty
huge. Java uses 8k by default, and Go uses 4k for reference.
- Make punctuation/formatting consistent with the changes made to "The
Rust Programming Language" in #20782.
- Use title casing for "Safety and Speed" section.
- Reword some phrases to improve clarity.
rust-mode.el recently started highlighting keywords that were substrings of identifiers. Identifiers such as `xyz_type` would have `type` highlighted, which isn't normal. This patch re-introduces `_` as a word constituent, so that keywords following a `_` don't get syntax highlighted as keywords. Fixes issue #20422
Projection predicates on re-exports, for the time being, are rendered as
equality predicates because that's easier. It would be nice to fix this
in the future.
Some gymnastics were needed to remove redundant bounds from the `types`
and `lifetimes` fields, remove implicit `Sized` bounds, and re-create
`?Sized` bounds.
Fix#20203, fix#20924, fix#20911, fix#20534
#### 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
