diff options
8 files changed, 48 insertions, 3 deletions
diff --git a/src/librustc_error_codes/error_codes.rs b/src/librustc_error_codes/error_codes.rs index e01412bc21c..2399e99a309 100644 --- a/src/librustc_error_codes/error_codes.rs +++ b/src/librustc_error_codes/error_codes.rs @@ -120,6 +120,7 @@ E0223: include_str!("./error_codes/E0223.md"), E0224: include_str!("./error_codes/E0224.md"), E0225: include_str!("./error_codes/E0225.md"), E0226: include_str!("./error_codes/E0226.md"), +E0228: include_str!("./error_codes/E0228.md"), E0229: include_str!("./error_codes/E0229.md"), E0230: include_str!("./error_codes/E0230.md"), E0231: include_str!("./error_codes/E0231.md"), @@ -482,7 +483,6 @@ E0753: include_str!("./error_codes/E0753.md"), // E0218, // no associated type defined // E0219, // associated type defined in higher-ranked supertrait E0227, // ambiguous lifetime bound, explicit lifetime bound required - E0228, // explicit lifetime bound required // E0233, // E0234, // E0235, // structure constructor specifies a structure of type but diff --git a/src/librustc_error_codes/error_codes/E0228.md b/src/librustc_error_codes/error_codes/E0228.md new file mode 100644 index 00000000000..3443a5ae863 --- /dev/null +++ b/src/librustc_error_codes/error_codes/E0228.md @@ -0,0 +1,40 @@ +The lifetime bound for this object type cannot be deduced from context and must +be specified. + +Erroneous code example: + +```compile_fail,E0228 +trait Trait { } + +struct TwoBounds<'a, 'b, T: Sized + 'a + 'b> { + x: &'a i32, + y: &'b i32, + z: T, +} + +type Foo<'a, 'b> = TwoBounds<'a, 'b, dyn Trait>; +``` + +When a trait object is used as a type argument of a generic type, Rust will try +to infer its lifetime if unspecified. However, this isn't possible when the +containing type has more than one lifetime bound. + +The above example can be resolved by either reducing the number of lifetime +bounds to one or by making the trait object lifetime explicit, like so: + +``` +trait Trait { } + +struct TwoBounds<'a, 'b, T: Sized + 'a + 'b> { + x: &'a i32, + y: &'b i32, + z: T, +} + +type Foo<'a, 'b> = TwoBounds<'a, 'b, dyn Trait + 'b>; +``` + +For more information, see [RFC 599] and its amendment [RFC 1156]. + +[RFC 599]: https://github.com/rust-lang/rfcs/blob/master/text/0599-default-object-bound.md +[RFC 1156]: https://github.com/rust-lang/rfcs/blob/master/text/1156-adjust-default-object-bounds.md diff --git a/src/test/ui/object-lifetime/object-lifetime-default-ambiguous.stderr b/src/test/ui/object-lifetime/object-lifetime-default-ambiguous.stderr index 0c3dbffeea6..bd50a27fd5e 100644 --- a/src/test/ui/object-lifetime/object-lifetime-default-ambiguous.stderr +++ b/src/test/ui/object-lifetime/object-lifetime-default-ambiguous.stderr @@ -18,3 +18,4 @@ LL | fn f(t: &Ref2<dyn Test>) { error: aborting due to 3 previous errors +For more information about this error, try `rustc --explain E0228`. diff --git a/src/test/ui/object-lifetime/object-lifetime-default-dyn-binding-nonstatic1.stderr b/src/test/ui/object-lifetime/object-lifetime-default-dyn-binding-nonstatic1.stderr index 9dbf7a78ed7..f06a9da1dee 100644 --- a/src/test/ui/object-lifetime/object-lifetime-default-dyn-binding-nonstatic1.stderr +++ b/src/test/ui/object-lifetime/object-lifetime-default-dyn-binding-nonstatic1.stderr @@ -6,3 +6,4 @@ LL | fn bar<'a>(x: &'a str) -> &'a dyn Foo<'a, Item = dyn Bar> { &() } error: aborting due to previous error +For more information about this error, try `rustc --explain E0228`. diff --git a/src/test/ui/object-lifetime/object-lifetime-default-dyn-binding-nonstatic2.stderr b/src/test/ui/object-lifetime/object-lifetime-default-dyn-binding-nonstatic2.stderr index d069f52ce47..51d8450af76 100644 --- a/src/test/ui/object-lifetime/object-lifetime-default-dyn-binding-nonstatic2.stderr +++ b/src/test/ui/object-lifetime/object-lifetime-default-dyn-binding-nonstatic2.stderr @@ -6,3 +6,4 @@ LL | fn bar<'a>(x: &'a str) -> &'a dyn Foo<'a, Item = dyn Bar> { &() } error: aborting due to previous error +For more information about this error, try `rustc --explain E0228`. diff --git a/src/test/ui/object-lifetime/object-lifetime-default-dyn-binding-nonstatic3.stderr b/src/test/ui/object-lifetime/object-lifetime-default-dyn-binding-nonstatic3.stderr index 9c7b6b98f2e..f721bf39419 100644 --- a/src/test/ui/object-lifetime/object-lifetime-default-dyn-binding-nonstatic3.stderr +++ b/src/test/ui/object-lifetime/object-lifetime-default-dyn-binding-nonstatic3.stderr @@ -6,3 +6,4 @@ LL | fn bar(x: &str) -> &dyn Foo<Item = dyn Bar> { &() } error: aborting due to previous error +For more information about this error, try `rustc --explain E0228`. diff --git a/src/test/ui/suggestions/missing-lifetime-specifier.stderr b/src/test/ui/suggestions/missing-lifetime-specifier.stderr index f5ff54cc916..2630cf1affa 100644 --- a/src/test/ui/suggestions/missing-lifetime-specifier.stderr +++ b/src/test/ui/suggestions/missing-lifetime-specifier.stderr @@ -252,5 +252,5 @@ LL | static f: RefCell<HashMap<i32, Vec<Vec<&Tar<'static, i32>>>>> = RefCell error: aborting due to 28 previous errors -Some errors have detailed explanations: E0106, E0107. +Some errors have detailed explanations: E0106, E0107, E0228. For more information about an error, try `rustc --explain E0106`. diff --git a/src/test/ui/underscore-lifetime/dyn-trait-underscore-in-struct.stderr b/src/test/ui/underscore-lifetime/dyn-trait-underscore-in-struct.stderr index fe242e6a909..2c595833cd1 100644 --- a/src/test/ui/underscore-lifetime/dyn-trait-underscore-in-struct.stderr +++ b/src/test/ui/underscore-lifetime/dyn-trait-underscore-in-struct.stderr @@ -18,4 +18,5 @@ LL | x: Box<dyn Debug + '_>, error: aborting due to 2 previous errors -For more information about this error, try `rustc --explain E0106`. +Some errors have detailed explanations: E0106, E0228. +For more information about an error, try `rustc --explain E0106`. |