Implement existential types

1 files changed, 49 insertions, 0 deletions

diff --git a/src/test/ui/str-array-assignment.stderr b/src/test/ui/str-array-assignment.stderr
new file mode 100644
index 00000000000..7a774cab38e
--- /dev/null
+++ b/src/test/ui/str-array-assignment.stderr
@@ -0,0 +1,49 @@
+error[E0308]: if and else have incompatible types
+  --> $DIR/str-array-assignment.rs:13:11
+   |
+LL |   let t = if true { s[..2] } else { s };
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected str, found &str
+   |
+   = note: expected type `str`
+              found type `&str`
+
+error[E0308]: mismatched types
+  --> $DIR/str-array-assignment.rs:15:27
+   |
+LL |   let u: &str = if true { s[..2] } else { s };
+   |                           ^^^^^^
+   |                           |
+   |                           expected &str, found str
+   |                           help: consider borrowing here: `&s[..2]`
+   |
+   = note: expected type `&str`
+              found type `str`
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/str-array-assignment.rs:17:7
+   |
+LL |   let v = s[..2];
+   |       ^   ------ help: consider borrowing here: `&s[..2]`
+   |       |
+   |       doesn't have a size known at compile-time
+   |
+   = help: the trait `std::marker::Sized` is not implemented for `str`
+   = note: to learn more, visit <https://doc.rust-lang.org/book/second-edition/ch19-04-advanced-types.html#dynamically-sized-types-and-sized>
+   = note: all local variables must have a statically known size
+
+error[E0308]: mismatched types
+  --> $DIR/str-array-assignment.rs:19:17
+   |
+LL |   let w: &str = s[..2];
+   |                 ^^^^^^
+   |                 |
+   |                 expected &str, found str
+   |                 help: consider borrowing here: `&s[..2]`
+   |
+   = note: expected type `&str`
+              found type `str`
+
+error: aborting due to 4 previous errors
+
+Some errors occurred: E0277, E0308.
+For more information about an error, try `rustc --explain E0277`.