Add regression test for #143128

Author: GuillaumeGomez

tests/ui/closures/missing-body.rs

@@ -0,0 +1,8 @@
+// Checks that the compiler complains about the missing closure body and does not
+// crash.
+// This is a regression test for <https://github.com/rust-lang/rust/issues/143128>.
+
+fn main() { | b : [str; _] | }
+//~^ ERROR expected expression, found `}`
+//~| ERROR the placeholder `_` is not allowed within types on item signatures for closures
+//~| ERROR the size for values of type `str` cannot be known at compilation time

tests/ui/closures/missing-body.stderr

@@ -0,0 +1,33 @@
+error: expected expression, found `}`
+  --> $DIR/missing-body.rs:5:30
+   |
+LL | fn main() { | b : [str; _] | }
+   |             ---------------- ^ expected expression
+   |             |
+   |             while parsing the body of this closure
+   |
+help: you might have meant to open the body of the closure, instead of enclosing the closure in a block
+   |
+LL - fn main() { | b : [str; _] | }
+LL + fn main()  | b : [str; _] | { }
+   |
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for closures
+  --> $DIR/missing-body.rs:5:25
+   |
+LL | fn main() { | b : [str; _] | }
+   |                         ^ not allowed in type signatures
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/missing-body.rs:5:19
+   |
+LL | fn main() { | b : [str; _] | }
+   |                   ^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+   = note: slice and array elements must have `Sized` type
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0121, E0277.
+For more information about an error, try `rustc --explain E0121`.