Auto merge of #74889 - JohnTitor:hrtb-tests, r=nikomatsakis

Add HRTB-related regression test

Closes #59311 and cc #71546
This closes the former but the test is taken from #71546 (comment) since it seems they have the same cause and it's simplified.

src/test/ui/higher-rank-trait-bounds/issue-59311.rs

@@ -0,0 +1,20 @@
+// Regression test for #59311. The test is taken from
+// rust-lang/rust/issues/71546#issuecomment-620638437
+// as they seem to have the same cause.
+
+// FIXME: It's not clear that this code ought to report
+// an error, but the regression test is here to ensure
+// that it does not ICE. See discussion on #74889 for details.
+
+pub trait T {
+    fn t<F: Fn()>(&self, _: F) {}
+}
+
+pub fn crash<V>(v: &V)
+where
+    for<'a> &'a V: T + 'static,
+{
+    v.t(|| {}); //~ ERROR: higher-ranked subtype error
+}
+
+fn main() {}

src/test/ui/higher-rank-trait-bounds/issue-59311.stderr

@@ -0,0 +1,8 @@
+error: higher-ranked subtype error
+  --> $DIR/issue-59311.rs:17:9
+   |
+LL |     v.t(|| {});
+   |         ^^^^^
+
+error: aborting due to previous error
+