Add a regression test for #54779

Author: JohnTitor

src/test/ui/nll/issue-54779-anon-static-lifetime.rs

@@ -0,0 +1,51 @@
+// Regression test for #54779, checks if the diagnostics are confusing.
+
+#![feature(nll)]
+
+trait DebugWith<Cx: ?Sized> {
+    fn debug_with<'me>(&'me self, cx: &'me Cx) -> DebugCxPair<'me, Self, Cx> {
+        DebugCxPair { value: self, cx }
+    }
+
+    fn fmt_with(&self, cx: &Cx, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result;
+}
+
+struct DebugCxPair<'me, Value: ?Sized, Cx: ?Sized>
+where
+    Value: DebugWith<Cx>,
+{
+    value: &'me Value,
+    cx: &'me Cx,
+}
+
+trait DebugContext {}
+
+struct Foo {
+    bar: Bar,
+}
+
+impl DebugWith<dyn DebugContext> for Foo {
+    fn fmt_with(
+        &self,
+        cx: &dyn DebugContext,
+        fmt: &mut std::fmt::Formatter<'_>,
+    ) -> std::fmt::Result {
+        let Foo { bar } = self;
+        bar.debug_with(cx); //~ ERROR: lifetime may not live long enough
+        Ok(())
+    }
+}
+
+struct Bar {}
+
+impl DebugWith<dyn DebugContext> for Bar {
+    fn fmt_with(
+        &self,
+        cx: &dyn DebugContext,
+        fmt: &mut std::fmt::Formatter<'_>,
+    ) -> std::fmt::Result {
+        Ok(())
+    }
+}
+
+fn main() {}

src/test/ui/nll/issue-54779-anon-static-lifetime.stderr

@@ -0,0 +1,11 @@
+error: lifetime may not live long enough
+  --> $DIR/issue-54779-anon-static-lifetime.rs:34:24
+   |
+LL |         cx: &dyn DebugContext,
+   |             - let's call the lifetime of this reference `'1`
+...
+LL |         bar.debug_with(cx);
+   |                        ^^ cast requires that `'1` must outlive `'static`
+
+error: aborting due to previous error
+