add tests from crater for liveness causing scope differences

Author: lqd

tests/ui/nll/polonius/location-insensitive-scopes-liveness.rs

@@ -0,0 +1,46 @@
+// This is a non-regression test about differences in scopes computed by NLLs and `-Zpolonius=next`
+// found during the crater run for PR #117593.
+//
+// Live loans were computed too early compared to some of the liveness data coming from later passes
+// than `liveness::trace`, on some specific CFGs shapes: a variable was dead during tracing but its
+// regions were marked live later, and live loans were not recomputed at this point.
+
+// check-pass
+// revisions: nll polonius
+// [polonius] compile-flags: -Zpolonius=next
+
+// minimized from wavefc-cli-3.0.0
+fn repro1() {
+    let a = 0;
+    let closure = || {
+        let _b = a;
+    };
+
+    let callback = if true { Some(closure) } else { None };
+    do_it(callback);
+}
+fn do_it<F>(_: Option<F>)
+where
+    F: Fn(),
+{
+}
+
+// minimized from simple-server-0.4.0
+fn repro2() {
+    let mut a = &();
+    let s = S(&mut a);
+    let _ = if true { Some(s) } else { None };
+}
+struct S<'a>(&'a mut &'a ());
+
+// minimized from https://github.com/SHaaD94/AICup2022
+fn repro3() {
+    let runner = ();
+    let writer = debug_interface(&runner);
+    let _ = if true { Some(writer) } else { None };
+}
+fn debug_interface(_: &()) -> &mut dyn std::io::Write {
+    unimplemented!()
+}
+
+fn main() {}