Add a more precise error message for issue #35976
When trying to perform static dispatch on something which derefs to a trait object, and the target trait is not in scope, we had confusing error messages if the target method had a `Self: Sized` bound. We add a more precise error message in this case: "consider using trait ...".
Fixes#35976.
r? @nikomatsakis
field does not exist error: note fields if Levenshtein suggestion fails
When trying to access or initialize a nonexistent field, if we can't infer what
field was meant (by virtue of the purported field in the source being a small
Levenshtein distance away from an actual field, suggestive of a typo), issue a
note listing all the available fields. To reduce terminal clutter, we don't
issue the note when we have a `find_best_match_for_name` Levenshtein
suggestion: the suggestion is probably right.
The third argument of the call to `find_best_match_for_name` is changed to
`None`, accepting the default maximum Levenshtein distance of one-third of the
identifier supplied for correction. The previous value of `Some(name.len())`
was overzealous, inappropriately very Levenshtein-distant suggestions when the
attempted field access could not plausibly be a mere typo. For example, if a
struct has fields `mule` and `phone`, but I type `.donkey`, I'd rather the
error have a note listing that the available fields are, in fact, `mule` and
`phone` (which is the behavior induced by this patch) rather than the error
asking "did you mean `phone`?" (which is the behavior on master). The "only
find fits with at least one matching letter" comment was accurate when it was
first introduced in 09d992471 (January 2015), but is a vicious lie in its
present context before a call to `find_best_match_for_name` and must be
destroyed (replacing every letter is within a Levenshtein distance of name.len()).
The present author claims that this suffices to resolve#42599.
trans::mir::constant - fix assignment error recovery
trans::mir::constant - fix assignment error recovery
We used to not store anything when the RHS of an assignment returned an error, which caused ICEs downstream.
Fixes#43197.
resolve: Try to fix instability in import suggestions
cc https://github.com/rust-lang/rust/pull/42033
`lookup_import_candidates` walks module graph in DFS order and skips modules that were already visited (which is correct because there can be cycles).
However it means that if we visited `std::prelude::v1::Result::Ok` first, we will never visit `std::result::Result::Ok` because `Result` will be skipped as already visited (note: enums are also modules here), and otherwise, if we visited `std::result::Result::Ok` first, we will never get to `std::prelude::v1::Result::Ok`.
What child module of `std` (`prelude` or `result`) we will visit first, depends on randomized hashing, so we have instability in diagnostics.
With this patch modules' children are visited in stable order in `lookup_import_candidates`, this should fix the issue, but let's see what Travis will say.
r? @oli-obk
Extended error message for mut borrow conflicts in loops
RFC issue: https://github.com/rust-lang/rfcs/issues/2080
The error message for multiple mutable borrows on the same value over loop iterations now makes it clear that the conflict comes from the borrow outlasting the loop. The wording of the error is based on the special case of the moved-value error for a value moved in a loop. Following the example of that error, the code remains the same for the special case.
This is mainly because I felt the current message is confusing in the loop case : https://github.com/rust-lang/rust/issues/43437. It's not clear that the two conflicting borrows are in different iterations of the loop, and instead it just looks like the compiler has an issue with a single line.
Point at path segment on module not found
Point at the correct path segment on a import statement where a module
doesn't exist.
New output:
```rust
error[E0432]: unresolved import `std::bar`
--> <anon>:1:10
|
1 | use std::bar::{foo1, foo2};
| ^^^ Could not find `bar` in `std`
```
instead of:
```rust
error[E0432]: unresolved import `std::bar::foo1`
--> <anon>:1:16
|
1 | use std::bar::{foo1, foo2};
| ^^^^ Could not find `bar` in `std`
error[E0432]: unresolved import `std::bar::foo2`
--> <anon>:1:22
|
1 | use std::bar::{foo1, foo2};
| ^^^^ Could not find `bar` in `std`
```
Fix#43040.
Make the "main" constructors of NonZero/Shared/Unique return Option
Per discussion in https://github.com/rust-lang/rust/issues/27730#issuecomment-303939441.
This is a breaking change to unstable APIs.
The old behavior is still available under the name `new_unchecked`. Note that only that one can be `const fn`, since `if` is currently not allowed in constant contexts.
In the case of `NonZero` this requires adding a new `is_zero` method to the `Zeroable` trait. I mildly dislike this, but it’s not much worse than having a `Zeroable` trait in the first place. `Zeroable` and `NonZero` are both unstable, this can be reworked later.
Point at the correct path segment on a import statement where a module
doesn't exist.
New output:
```rust
error[E0432]: unresolved import `std::bar`
--> <anon>:1:10
|
1 | use std::bar::{foo1, foo2};
| ^^^ Could not find `bar` in `std`
```
instead of:
```rust
error[E0432]: unresolved import `std::bar::foo1`
--> <anon>:1:16
|
1 | use std::bar::{foo1, foo2};
| ^^^^ Could not find `bar` in `std`
error[E0432]: unresolved import `std::bar::foo2`
--> <anon>:1:22
|
1 | use std::bar::{foo1, foo2};
| ^^^^ Could not find `bar` in `std`
```
When trying to access or initialize a nonexistent field, if we can't infer what
field was meant (by virtue of the purported field in the source being a small
Levenshtein distance away from an actual field, suggestive of a typo), issue a
note listing all the available fields. To reduce terminal clutter, we don't
issue the note when we have a `find_best_match_for_name` Levenshtein
suggestion: the suggestion is probably right.
The third argument of the call to `find_best_match_for_name` is changed to
`None`, accepting the default maximum Levenshtein distance of one-third of the
identifier supplied for correction. The previous value of `Some(name.len())`
was overzealous, inappropriately very Levenshtein-distant suggestions when the
attempted field access could not plausibly be a mere typo. For example, if a
struct has fields `mule` and `phone`, but I type `.donkey`, I'd rather the
error have a note listing that the available fields are, in fact, `mule` and
`phone` (which is the behavior induced by this patch) rather than the error
asking "did you mean `phone`?" (which is the behavior on master). The "only
find fits with at least one matching letter" comment was accurate when it was
first introduced in 09d992471 (January 2015), but is a vicious lie in its
present context before a call to `find_best_match_for_name` and must be
destroyed (replacing every letter is a Levenshtein distance of name.len()).
The present author claims that this suffices to resolve#42599.
Point at `:` when using it instead of `;`
When triggering type ascription in such a way that we can infer a
statement end was intended, add a suggestion for the change. Always
point out the reason for the expectation of a type is due to type
ascription.
Fix#42057, #41928.
Less verbose output for unused arguments
Closes#37718
This is my first contribution to rust, so sorry if I'm missing anything!
The output now looks like this:
<img width="831" alt="screen shot 2017-07-18 at 5 01 32 pm" src="https://user-images.githubusercontent.com/12972285/28347566-dbfa9962-6c05-11e7-8730-c2e8062a04cc.png">
It's not the prettiest, but whenever #41850 gets resolved, this should be able to be improved.
**EDIT:** This also does not seem
r? @Mark-Simulacrum
Now there's a way to add suggestions that hide the suggested code when
presented inline, to avoid weird wording when short code snippets are
added at the end.
The produced paths aren't stable between builds, since
reporting paths inside resolve, before resolve is finished
might produce paths resolved to type aliases instead of
the concrete type.
Compile-fail tests can match just parts of messages, so they
don't "suffer" from this issue.
This is just a workaround, the instability should be fixed
in the future.
