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-rw-r--r--src/test/ui/hrtb/hrtb-cache-issue-54302.rs24
1 files changed, 24 insertions, 0 deletions
diff --git a/src/test/ui/hrtb/hrtb-cache-issue-54302.rs b/src/test/ui/hrtb/hrtb-cache-issue-54302.rs
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index 000000000..a20d03c77
--- /dev/null
+++ b/src/test/ui/hrtb/hrtb-cache-issue-54302.rs
@@ -0,0 +1,24 @@
+// Regression test for #54302.
+//
+// We were incorrectly using the "evaluation cache" (which ignored
+// region results) to conclude that `&'static str: Deserialize`, even
+// though it would require that `for<'de> 'de: 'static`, which is
+// clearly false.
+
+trait Deserialize<'de> {}
+
+trait DeserializeOwned: for<'de> Deserialize<'de> {}
+impl<T> DeserializeOwned for T where T: for<'de> Deserialize<'de> {}
+
+// Based on this impl, `&'static str` only implements Deserialize<'static>.
+// It does not implement for<'de> Deserialize<'de>.
+impl<'de: 'a, 'a> Deserialize<'de> for &'a str {}
+
+fn main() {
+ fn assert_deserialize_owned<T: DeserializeOwned>() {}
+ assert_deserialize_owned::<&'static str>(); //~ ERROR
+
+ // It correctly does not implement for<'de> Deserialize<'de>.
+ // fn assert_hrtb<T: for<'de> Deserialize<'de>>() {}
+ // assert_hrtb::<&'static str>();
+}