From eee09ec4263ac13d94e79b92bdd7df780330077a Mon Sep 17 00:00:00 2001
From: Aaron Hill <aa1ronham@gmail.com>
Date: Fri, 17 Dec 2021 10:27:26 -0500
Subject: Remove 'speculative evaluation' of predicates

Performing 'speculative evaluation' introduces caching bugs that
cannot be fixed without invasive changes to projection.

Hopefully, we can win back most of the performance lost by
re-adding 'cache completion'

Fixes #90662
---
 .../ui/traits/issue-90662-projection-caching.rs    | 34 ++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 src/test/ui/traits/issue-90662-projection-caching.rs

(limited to 'src')

diff --git a/src/test/ui/traits/issue-90662-projection-caching.rs b/src/test/ui/traits/issue-90662-projection-caching.rs
new file mode 100644
index 00000000000..879f30071bf
--- /dev/null
+++ b/src/test/ui/traits/issue-90662-projection-caching.rs
@@ -0,0 +1,34 @@
+// check-pass
+
+// Regression test for issue #90662
+// Tests that projection caching does not cause a spurious error
+
+trait HasProvider<T: ?Sized> {}
+trait Provider<M> {
+    type Interface: ?Sized;
+}
+
+trait Repository {}
+trait Service {}
+
+struct DbConnection;
+impl<M> Provider<M> for DbConnection {
+    type Interface = DbConnection;
+}
+
+struct RepositoryImpl;
+impl<M: HasProvider<DbConnection>> Provider<M> for RepositoryImpl {
+    type Interface = dyn Repository;
+}
+
+struct ServiceImpl;
+impl<M: HasProvider<dyn Repository>> Provider<M> for ServiceImpl {
+    type Interface = dyn Service;
+}
+
+struct TestModule;
+impl HasProvider<<DbConnection as Provider<Self>>::Interface> for TestModule {}
+impl HasProvider<<RepositoryImpl as Provider<Self>>::Interface> for TestModule {}
+impl HasProvider<<ServiceImpl as Provider<Self>>::Interface> for TestModule {}
+
+fn main() {}
-- 
cgit 1.4.1-3-g733a5