Better error messages when collecting into `[T; n]`

4 files changed, 25 insertions, 2 deletions

diff --git a/src/test/ui/iterators/collect-into-array.rs b/src/test/ui/iterators/collect-into-array.rs
new file mode 100644
index 00000000000..a1144c8cb8c
--- /dev/null
+++ b/src/test/ui/iterators/collect-into-array.rs
@@ -0,0 +1,7 @@
+fn main() {
+    //~^ NOTE required by a bound in this
+    let whatever: [u32; 10] = (0..10).collect();
+    //~^ ERROR an array of type `[u32; 10]` cannot be built directly from an iterator
+    //~| NOTE try collecting into a `Vec<{integer}>`, then using `.try_into()`
+    //~| NOTE required by a bound in `collect`
+}
diff --git a/src/test/ui/iterators/collect-into-array.stderr b/src/test/ui/iterators/collect-into-array.stderr
new file mode 100644
index 00000000000..7be53a4873b
--- /dev/null
+++ b/src/test/ui/iterators/collect-into-array.stderr
@@ -0,0 +1,16 @@
+error[E0277]: an array of type `[u32; 10]` cannot be built directly from an iterator
+  --> $DIR/collect-into-array.rs:3:39
+   |
+LL |     let whatever: [u32; 10] = (0..10).collect();
+   |                                       ^^^^^^^ try collecting into a `Vec<{integer}>`, then using `.try_into()`
+   |
+   = help: the trait `FromIterator<{integer}>` is not implemented for `[u32; 10]`
+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 previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/iterators/collect-into-slice.rs b/src/test/ui/iterators/collect-into-slice.rs
index 905752dec74..aafa6bc8b95 100644
--- a/src/test/ui/iterators/collect-into-slice.rs
+++ b/src/test/ui/iterators/collect-into-slice.rs
@@ -6,7 +6,7 @@ fn process_slice(data: &[i32]) {
 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
+    //~| ERROR a slice 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
diff --git a/src/test/ui/iterators/collect-into-slice.stderr b/src/test/ui/iterators/collect-into-slice.stderr
index 521f239451d..4842e65fe97 100644
--- a/src/test/ui/iterators/collect-into-slice.stderr
+++ b/src/test/ui/iterators/collect-into-slice.stderr
@@ -8,7 +8,7 @@ LL |     let some_generated_vec = (0..10).collect();
    = 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
+error[E0277]: a slice 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();