diff options
| -rw-r--r-- | library/core/src/iter/traits/collect.rs | 26 | ||||
| -rw-r--r-- | src/test/ui/iterators/collect-into-slice.rs | 15 | ||||
| -rw-r--r-- | src/test/ui/iterators/collect-into-slice.stderr | 26 |
3 files changed, 67 insertions, 0 deletions
diff --git a/library/core/src/iter/traits/collect.rs b/library/core/src/iter/traits/collect.rs index fc14620a2df..637d7bc4488 100644 --- a/library/core/src/iter/traits/collect.rs +++ b/library/core/src/iter/traits/collect.rs @@ -81,6 +81,32 @@ /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[rustc_on_unimplemented( + on( + _Self = "[{A}]", + message = "a value of type `{Self}` cannot be built since `{Self}` has no definite size", + label = "try explicitly collecting into a `Vec<{A}>`", + ), + on( + all( + A = "{integer}", + any( + _Self = "[i8]", + _Self = "[i16]", + _Self = "[i32]", + _Self = "[i64]", + _Self = "[i128]", + _Self = "[isize]", + _Self = "[u8]", + _Self = "[u16]", + _Self = "[u32]", + _Self = "[u64]", + _Self = "[u128]", + _Self = "[usize]" + ) + ), + message = "a value of type `{Self}` cannot be built since `{Self}` has no definite size", + label = "try explicitly collecting into a `Vec<{A}>`", + ), message = "a value of type `{Self}` cannot be built from an iterator \ over elements of type `{A}`", label = "value of type `{Self}` cannot be built from `std::iter::Iterator<Item={A}>`" diff --git a/src/test/ui/iterators/collect-into-slice.rs b/src/test/ui/iterators/collect-into-slice.rs new file mode 100644 index 00000000000..905752dec74 --- /dev/null +++ b/src/test/ui/iterators/collect-into-slice.rs @@ -0,0 +1,15 @@ +fn process_slice(data: &[i32]) { + //~^ NOTE required by a bound in this + todo!() +} + +fn main() { + let some_generated_vec = (0..10).collect(); + //~^ ERROR the size for values of type `[i32]` cannot be known at compilation time + //~| ERROR a value of type `[i32]` cannot be built since `[i32]` has no definite size + //~| NOTE try explicitly collecting into a `Vec<{integer}>` + //~| NOTE required by a bound in `collect` + //~| NOTE all local variables must have a statically known size + //~| NOTE doesn't have a size known at compile-time + process_slice(&some_generated_vec); +} diff --git a/src/test/ui/iterators/collect-into-slice.stderr b/src/test/ui/iterators/collect-into-slice.stderr new file mode 100644 index 00000000000..521f239451d --- /dev/null +++ b/src/test/ui/iterators/collect-into-slice.stderr @@ -0,0 +1,26 @@ +error[E0277]: the size for values of type `[i32]` cannot be known at compilation time + --> $DIR/collect-into-slice.rs:7:9 + | +LL | let some_generated_vec = (0..10).collect(); + | ^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time + | + = help: the trait `Sized` is not implemented for `[i32]` + = note: all local variables must have a statically known size + = help: unsized locals are gated as an unstable feature + +error[E0277]: a value of type `[i32]` cannot be built since `[i32]` has no definite size + --> $DIR/collect-into-slice.rs:7:38 + | +LL | let some_generated_vec = (0..10).collect(); + | ^^^^^^^ try explicitly collecting into a `Vec<{integer}>` + | + = help: the trait `FromIterator<{integer}>` is not implemented for `[i32]` +note: required by a bound in `collect` + --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL + | +LL | fn collect<B: FromIterator<Self::Item>>(self) -> B + | ^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `collect` + +error: aborting due to 2 previous errors + +For more information about this error, try `rustc --explain E0277`. |