Add test for issue-36122

Author: JohnTitor

src/test/ui/extern/issue-36122-accessing-externed-dst.rs

@@ -0,0 +1,6 @@
+fn main() {
+    extern {
+        static symbol: [usize]; //~ ERROR: the size for values of type
+    }
+    println!("{}", symbol[0]);
+}

src/test/ui/extern/issue-36122-accessing-externed-dst.stderr

@@ -0,0 +1,12 @@
+error[E0277]: the size for values of type `[usize]` cannot be known at compilation time
+  --> $DIR/issue-36122-accessing-externed-dst.rs:3:24
+   |
+LL |         static symbol: [usize];
+   |                        ^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `std::marker::Sized` is not implemented for `[usize]`
+   = note: to learn more, visit <https://doc.rust-lang.org/book/ch19-04-advanced-types.html#dynamically-sized-types-and-the-sized-trait>
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.