rust/src/test/ui/deref-suggestion.stderr

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error[E0308]: mismatched types
--> $DIR/deref-suggestion.rs:18:9
|
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LL | foo(s); //~ ERROR mismatched types
type error method suggestions use whitelisted identity-like conversions Previously, on a type mismatch (and if this wasn't preëmpted by a higher-priority suggestion), we would look for argumentless methods returning the expected type, and list them in a `help` note. This had two major shortcomings. Firstly, a lot of the suggestions didn't really make sense (if you used a &str where a String was expected, `.to_ascii_uppercase()` is probably not the solution you were hoping for). Secondly, we weren't generating suggestions from the most useful traits! We address the first problem with an internal `#[rustc_conversion_suggestion]` attribute meant to mark methods that keep the "same value" in the relevant sense, just converting the type. We address the second problem by making `FnCtxt.probe_for_return_type` pass the `ProbeScope::AllTraits` to `probe_op`: this would seem to be safe because grep reveals no other callers of `probe_for_return_type`. Also, structured suggestions are preferred (because they're pretty, but also for RLS and friends). Also also, we make the E0055 autoderef recursion limit error use the one-time-diagnostics set, because we can potentially hit the limit a lot during probing. (Without this, test/ui/did_you_mean/recursion_limit_deref.rs would report "aborting due to 51 errors"). Unfortunately, the trait probing is still not all one would hope for: at a minimum, we don't know how to rule out `into()` in cases where it wouldn't actually work, and we don't know how to rule in `.to_owned()` where it would. Issues #46459 and #46460 have been filed and are ref'd in a FIXME. This is hoped to resolve #42929, #44672, and #45777.
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| ^
| |
| expected struct `std::string::String`, found reference
| help: try using a conversion method: `s.to_string()`
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|
= note: expected type `std::string::String`
found type `&std::string::String`
error[E0308]: mismatched types
--> $DIR/deref-suggestion.rs:23:10
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LL | foo3(u); //~ ERROR mismatched types
| ^
| |
| expected u32, found &u32
| help: consider dereferencing the borrow: `*u`
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|
= note: expected type `u32`
found type `&u32`
error[E0308]: mismatched types
--> $DIR/deref-suggestion.rs:30:9
|
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LL | foo(&"aaa".to_owned()); //~ ERROR mismatched types
| ^^^^^^^^^^^^^^^^^
| |
| expected struct `std::string::String`, found reference
| help: consider removing the borrow: `"aaa".to_owned()`
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|
= note: expected type `std::string::String`
found type `&std::string::String`
error[E0308]: mismatched types
--> $DIR/deref-suggestion.rs:31:9
|
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LL | foo(&mut "aaa".to_owned()); //~ ERROR mismatched types
| ^^^^^^^^^^^^^^^^^^^^^
| |
| expected struct `std::string::String`, found mutable reference
| help: consider removing the borrow: `"aaa".to_owned()`
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|
= note: expected type `std::string::String`
found type `&mut std::string::String`
error[E0308]: mismatched types
--> $DIR/deref-suggestion.rs:12:20
|
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LL | ($x:expr) => { &$x } //~ ERROR mismatched types
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| ^^^ expected u32, found &{integer}
...
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LL | foo3(borrow!(0));
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| ---------- in this macro invocation
|
= note: expected type `u32`
found type `&{integer}`
error: aborting due to 5 previous errors
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For more information about this error, try `rustc --explain E0308`.