Rollup merge of #63560 - Centril:mv-generator-test, r=petrochenkov

move test that shouldn't be in test/run-pass/

We no longer test `src/test/run-pass/`; the proper way now is `// run-pass` in `src/test/ui/`

r? @petrochenkov

src/test/ui/generator/niche-in-generator.rs

@@ -0,0 +1,19 @@
+// Test that niche finding works with captured generator upvars.
+
+// run-pass
+
+#![feature(generators)]
+
+use std::mem::size_of_val;
+
+fn take<T>(_: T) {}
+
+fn main() {
+    let x = false;
+    let gen1 = || {
+        yield;
+        take(x);
+    };
+
+    assert_eq!(size_of_val(&gen1), size_of_val(&Some(gen1)));
+}