93ab12eeab
This PR has several interconnected pieces: 1. In some of the NLL region error code, we now pass around an `ObligationCause`, instead of just a plain `Span`. This gets forwarded into `fulfill_cx.register_predicate_obligation` during error reporting. 2. The general InferCtxt error reporting code is extended to handle `ObligationCauseCode::BindingObligation` 3. A new enum variant `ConstraintCategory::Predicate` is added. We try to avoid using this as the 'best blame constraint' - instead, we use it to enhance the `ObligationCause` of the `BlameConstraint` that we do end up choosing. As a result, several NLL error messages now contain the same "the lifetime requirement is introduced here" message as non-NLL errors. Having an `ObligationCause` available will likely prove useful for future improvements to NLL error messages.
78 lines
2.6 KiB
Plaintext
78 lines
2.6 KiB
Plaintext
error: lifetime may not live long enough
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--> $DIR/issue-79187-2.rs:9:24
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LL | take_foo(|a: &i32| a);
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| - - ^ returning this value requires that `'1` must outlive `'2`
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| | |
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| | return type of closure is &'2 i32
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| let's call the lifetime of this reference `'1`
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error: lifetime may not live long enough
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--> $DIR/issue-79187-2.rs:10:34
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LL | take_foo(|a: &i32| -> &i32 { a });
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| - - ^ returning this value requires that `'1` must outlive `'2`
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| | |
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| | let's call the lifetime of this reference `'2`
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| let's call the lifetime of this reference `'1`
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error: implementation of `FnOnce` is not general enough
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--> $DIR/issue-79187-2.rs:8:5
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LL | take_foo(|a| a);
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| ^^^^^^^^^^^^^^^ implementation of `FnOnce` is not general enough
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= note: closure with signature `fn(&'2 i32) -> &i32` must implement `FnOnce<(&'1 i32,)>`, for any lifetime `'1`...
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= note: ...but it actually implements `FnOnce<(&'2 i32,)>`, for some specific lifetime `'2`
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error[E0308]: mismatched types
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--> $DIR/issue-79187-2.rs:8:5
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LL | take_foo(|a| a);
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| ^^^^^^^^^^^^^^^ one type is more general than the other
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= note: expected type `for<'r> Fn<(&'r i32,)>`
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found type `Fn<(&i32,)>`
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note: this closure does not fulfill the lifetime requirements
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--> $DIR/issue-79187-2.rs:8:14
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LL | take_foo(|a| a);
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| ^^^^^
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note: the lifetime requirement is introduced here
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--> $DIR/issue-79187-2.rs:5:21
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LL | fn take_foo(_: impl Foo) {}
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| ^^^
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error[E0308]: mismatched types
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--> $DIR/issue-79187-2.rs:9:5
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LL | take_foo(|a: &i32| a);
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| ^^^^^^^^^^^^^^^^^^^^^ one type is more general than the other
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= note: expected reference `&i32`
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found reference `&i32`
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note: the lifetime requirement is introduced here
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--> $DIR/issue-79187-2.rs:5:21
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LL | fn take_foo(_: impl Foo) {}
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| ^^^
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error[E0308]: mismatched types
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--> $DIR/issue-79187-2.rs:10:5
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LL | take_foo(|a: &i32| -> &i32 { a });
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ one type is more general than the other
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= note: expected reference `&i32`
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found reference `&i32`
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note: the lifetime requirement is introduced here
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--> $DIR/issue-79187-2.rs:5:21
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LL | fn take_foo(_: impl Foo) {}
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| ^^^
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error: aborting due to 6 previous errors
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For more information about this error, try `rustc --explain E0308`.
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