diff options
3 files changed, 191 insertions, 8 deletions
diff --git a/src/librustc/traits/error_reporting/suggestions.rs b/src/librustc/traits/error_reporting/suggestions.rs index 4559007ea42..12c8de17d10 100644 --- a/src/librustc/traits/error_reporting/suggestions.rs +++ b/src/librustc/traits/error_reporting/suggestions.rs @@ -606,11 +606,13 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> { let tables = self.in_progress_tables.map(|t| t.borrow()).unwrap(); let mut ret_types = visitor.0.iter().filter_map(|expr| tables.node_type_opt(expr.hir_id)); - let (last_ty, all_returns_have_same_type) = - ret_types.clone().fold((None, true), |(last_ty, mut same), returned_ty| { - same &= last_ty.map_or(true, |ty| ty == returned_ty); - (Some(returned_ty), same) - }); + let (last_ty, all_returns_have_same_type) = ret_types.clone().fold( + (None, true), + |(last_ty, mut same): (std::option::Option<Ty<'_>>, bool), ty| { + same &= last_ty.map_or(true, |last_ty| last_ty == ty) && ty.kind != ty::Error; + (Some(ty), same) + }, + ); let all_returns_conform_to_trait = if let Some(ty_ret_ty) = tables.node_type_opt(ret_ty.hir_id) { match ty_ret_ty.kind { @@ -625,7 +627,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> { }) }) } - _ => true, + _ => false, } } else { true diff --git a/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.rs b/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.rs index b70a51dc825..93414379fd4 100644 --- a/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.rs +++ b/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.rs @@ -22,6 +22,32 @@ fn bal() -> dyn Trait { //~ ERROR E0746 } 42 } +fn bam() -> Box<dyn Trait> { + if true { + return Struct; //~ ERROR mismatched types + } + 42 //~ ERROR mismatched types +} +fn baq() -> Box<dyn Trait> { + if true { + return 0; //~ ERROR mismatched types + } + 42 //~ ERROR mismatched types +} +fn baz() -> Box<dyn Trait> { + if true { + Struct //~ ERROR mismatched types + } else { + 42 //~ ERROR mismatched types + } +} +fn baw() -> Box<dyn Trait> { + if true { + 0 //~ ERROR mismatched types + } else { + 42 //~ ERROR mismatched types + } +} // Suggest using `impl Trait` fn bat() -> dyn Trait { //~ ERROR E0746 @@ -30,5 +56,12 @@ fn bat() -> dyn Trait { //~ ERROR E0746 } 42 } +fn bay() -> dyn Trait { //~ ERROR E0746 + if true { + 0u32 + } else { + 42u32 + } +} fn main() {} diff --git a/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr b/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr index 977a7ef0e02..0df6e8f8dc7 100644 --- a/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr +++ b/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr @@ -95,8 +95,136 @@ LL | } LL | Box::new(42) | +error[E0308]: mismatched types + --> $DIR/dyn-trait-return-should-be-impl-trait.rs:27:16 + | +LL | fn bam() -> Box<dyn Trait> { + | -------------- expected `std::boxed::Box<(dyn Trait + 'static)>` because of return type +LL | if true { +LL | return Struct; + | ^^^^^^ + | | + | expected struct `std::boxed::Box`, found struct `Struct` + | help: store this in the heap by calling `Box::new`: `Box::new(Struct)` + | + = note: expected struct `std::boxed::Box<(dyn Trait + 'static)>` + found struct `Struct` + = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html + +error[E0308]: mismatched types + --> $DIR/dyn-trait-return-should-be-impl-trait.rs:29:5 + | +LL | fn bam() -> Box<dyn Trait> { + | -------------- expected `std::boxed::Box<(dyn Trait + 'static)>` because of return type +... +LL | 42 + | ^^ + | | + | expected struct `std::boxed::Box`, found integer + | help: store this in the heap by calling `Box::new`: `Box::new(42)` + | + = note: expected struct `std::boxed::Box<(dyn Trait + 'static)>` + found type `{integer}` + = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html + +error[E0308]: mismatched types + --> $DIR/dyn-trait-return-should-be-impl-trait.rs:33:16 + | +LL | fn baq() -> Box<dyn Trait> { + | -------------- expected `std::boxed::Box<(dyn Trait + 'static)>` because of return type +LL | if true { +LL | return 0; + | ^ + | | + | expected struct `std::boxed::Box`, found integer + | help: store this in the heap by calling `Box::new`: `Box::new(0)` + | + = note: expected struct `std::boxed::Box<(dyn Trait + 'static)>` + found type `{integer}` + = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html + +error[E0308]: mismatched types + --> $DIR/dyn-trait-return-should-be-impl-trait.rs:35:5 + | +LL | fn baq() -> Box<dyn Trait> { + | -------------- expected `std::boxed::Box<(dyn Trait + 'static)>` because of return type +... +LL | 42 + | ^^ + | | + | expected struct `std::boxed::Box`, found integer + | help: store this in the heap by calling `Box::new`: `Box::new(42)` + | + = note: expected struct `std::boxed::Box<(dyn Trait + 'static)>` + found type `{integer}` + = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html + +error[E0308]: mismatched types + --> $DIR/dyn-trait-return-should-be-impl-trait.rs:39:9 + | +LL | fn baz() -> Box<dyn Trait> { + | -------------- expected `std::boxed::Box<(dyn Trait + 'static)>` because of return type +LL | if true { +LL | Struct + | ^^^^^^ + | | + | expected struct `std::boxed::Box`, found struct `Struct` + | help: store this in the heap by calling `Box::new`: `Box::new(Struct)` + | + = note: expected struct `std::boxed::Box<(dyn Trait + 'static)>` + found struct `Struct` + = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html + +error[E0308]: mismatched types + --> $DIR/dyn-trait-return-should-be-impl-trait.rs:41:9 + | +LL | fn baz() -> Box<dyn Trait> { + | -------------- expected `std::boxed::Box<(dyn Trait + 'static)>` because of return type +... +LL | 42 + | ^^ + | | + | expected struct `std::boxed::Box`, found integer + | help: store this in the heap by calling `Box::new`: `Box::new(42)` + | + = note: expected struct `std::boxed::Box<(dyn Trait + 'static)>` + found type `{integer}` + = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html + +error[E0308]: mismatched types + --> $DIR/dyn-trait-return-should-be-impl-trait.rs:46:9 + | +LL | fn baw() -> Box<dyn Trait> { + | -------------- expected `std::boxed::Box<(dyn Trait + 'static)>` because of return type +LL | if true { +LL | 0 + | ^ + | | + | expected struct `std::boxed::Box`, found integer + | help: store this in the heap by calling `Box::new`: `Box::new(0)` + | + = note: expected struct `std::boxed::Box<(dyn Trait + 'static)>` + found type `{integer}` + = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html + +error[E0308]: mismatched types + --> $DIR/dyn-trait-return-should-be-impl-trait.rs:48:9 + | +LL | fn baw() -> Box<dyn Trait> { + | -------------- expected `std::boxed::Box<(dyn Trait + 'static)>` because of return type +... +LL | 42 + | ^^ + | | + | expected struct `std::boxed::Box`, found integer + | help: store this in the heap by calling `Box::new`: `Box::new(42)` + | + = note: expected struct `std::boxed::Box<(dyn Trait + 'static)>` + found type `{integer}` + = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html + error[E0746]: return type cannot have an unboxed trait object - --> $DIR/dyn-trait-return-should-be-impl-trait.rs:27:13 + --> $DIR/dyn-trait-return-should-be-impl-trait.rs:53:13 | LL | fn bat() -> dyn Trait { | ^^^^^^^^^ doesn't have a size known at compile-time @@ -107,7 +235,27 @@ help: return `impl Trait` instead, as all return paths are of type `{integer}`, LL | fn bat() -> impl Trait { | ^^^^^^^^^^ -error: aborting due to 9 previous errors +error[E0746]: return type cannot have an unboxed trait object + --> $DIR/dyn-trait-return-should-be-impl-trait.rs:59:13 + | +LL | fn bay() -> dyn Trait { + | ^^^^^^^^^ doesn't have a size known at compile-time + | + = note: for information on trait objects, see <https://doc.rust-lang.org/book/ch17-02-trait-objects.html#using-trait-objects-that-allow-for-values-of-different-types> + = note: if all the returned values were of the same type you could use `impl Trait` as the return type + = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits> + = note: you can create a new `enum` with a variant for each returned type +help: return a boxed trait object instead + | +LL | fn bay() -> Box<dyn Trait> { +LL | Box::new(if true { +LL | 0u32 +LL | } else { +LL | 42u32 +LL | }) + | + +error: aborting due to 18 previous errors Some errors have detailed explanations: E0277, E0308, E0746. For more information about an error, try `rustc --explain E0277`. |