add test for issue 117146

Author: lqd

tests/ui/nll/polonius/location-insensitive-scopes-issue-117146.nll.stderr

@@ -0,0 +1,40 @@
+error[E0597]: `a` does not live long enough
+  --> $DIR/location-insensitive-scopes-issue-117146.rs:10:18
+   |
+LL |     let b = |_| &a;
+   |             --- -^
+   |             |   ||
+   |             |   |borrowed value does not live long enough
+   |             |   returning this value requires that `a` is borrowed for `'static`
+   |             value captured here
+...
+LL | }
+   | - `a` dropped here while still borrowed
+   |
+note: due to current limitations in the borrow checker, this implies a `'static` lifetime
+  --> $DIR/location-insensitive-scopes-issue-117146.rs:20:22
+   |
+LL | fn bad<F: Fn(&()) -> &()>(_: F) {}
+   |                      ^^^
+
+error: implementation of `Fn` is not general enough
+  --> $DIR/location-insensitive-scopes-issue-117146.rs:13:5
+   |
+LL |     bad(&b);
+   |     ^^^^^^^ implementation of `Fn` is not general enough
+   |
+   = note: closure with signature `fn(&'2 ()) -> &()` must implement `Fn<(&'1 (),)>`, for any lifetime `'1`...
+   = note: ...but it actually implements `Fn<(&'2 (),)>`, for some specific lifetime `'2`
+
+error: implementation of `FnOnce` is not general enough
+  --> $DIR/location-insensitive-scopes-issue-117146.rs:13:5
+   |
+LL |     bad(&b);
+   |     ^^^^^^^ implementation of `FnOnce` is not general enough
+   |
+   = note: closure with signature `fn(&'2 ()) -> &()` must implement `FnOnce<(&'1 (),)>`, for any lifetime `'1`...
+   = note: ...but it actually implements `FnOnce<(&'2 (),)>`, for some specific lifetime `'2`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0597`.

tests/ui/nll/polonius/location-insensitive-scopes-issue-117146.polonius.stderr

@@ -0,0 +1,40 @@
+error[E0597]: `a` does not live long enough
+  --> $DIR/location-insensitive-scopes-issue-117146.rs:10:18
+   |
+LL |     let b = |_| &a;
+   |             --- -^
+   |             |   ||
+   |             |   |borrowed value does not live long enough
+   |             |   returning this value requires that `a` is borrowed for `'static`
+   |             value captured here
+...
+LL | }
+   | - `a` dropped here while still borrowed
+   |
+note: due to current limitations in the borrow checker, this implies a `'static` lifetime
+  --> $DIR/location-insensitive-scopes-issue-117146.rs:20:22
+   |
+LL | fn bad<F: Fn(&()) -> &()>(_: F) {}
+   |                      ^^^
+
+error: implementation of `Fn` is not general enough
+  --> $DIR/location-insensitive-scopes-issue-117146.rs:13:5
+   |
+LL |     bad(&b);
+   |     ^^^^^^^ implementation of `Fn` is not general enough
+   |
+   = note: closure with signature `fn(&'2 ()) -> &()` must implement `Fn<(&'1 (),)>`, for any lifetime `'1`...
+   = note: ...but it actually implements `Fn<(&'2 (),)>`, for some specific lifetime `'2`
+
+error: implementation of `FnOnce` is not general enough
+  --> $DIR/location-insensitive-scopes-issue-117146.rs:13:5
+   |
+LL |     bad(&b);
+   |     ^^^^^^^ implementation of `FnOnce` is not general enough
+   |
+   = note: closure with signature `fn(&'2 ()) -> &()` must implement `FnOnce<(&'1 (),)>`, for any lifetime `'1`...
+   = note: ...but it actually implements `FnOnce<(&'2 (),)>`, for some specific lifetime `'2`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0597`.

tests/ui/nll/polonius/location-insensitive-scopes-issue-117146.rs

@@ -0,0 +1,20 @@
+// This is a non-regression test for issue #117146, where NLL and `-Zpolonius=next` computed
+// different loan scopes when a region flowed into an SCC whose representative was an existential
+// region.
+
+// revisions: nll polonius
+// [polonius] compile-flags: -Zpolonius=next
+
+fn main() {
+    let a = ();
+    let b = |_| &a;
+    //[nll]~^ ERROR `a` does not live long enough
+    //[polonius]~^^ ERROR `a` does not live long enough
+    bad(&b);
+    //[nll]~^ ERROR implementation of `Fn`
+    //[nll]~| ERROR implementation of `FnOnce`
+    //[polonius]~^^^ ERROR implementation of `Fn`
+    //[polonius]~| ERROR implementation of `FnOnce`
+}
+
+fn bad<F: Fn(&()) -> &()>(_: F) {}