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-rw-r--r--src/test/ui/cross/cross-fn-cache-hole.rs31
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diff --git a/src/test/ui/cross/cross-fn-cache-hole.rs b/src/test/ui/cross/cross-fn-cache-hole.rs
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+// Check that when there are vacuous predicates in the environment
+// (which make a fn uncallable) we don't erroneously cache those and
+// then consider them satisfied elsewhere. The current technique for
+// doing this is to not use global caches when there is a chance that
+// the environment contains such a predicate.
+// We still error for `i32: Bar<u32>` pending #48214
+
+trait Foo<X,Y>: Bar<X> {
+}
+
+trait Bar<X> { }
+
+// We don't always check where clauses for sanity, but in this case
+// wfcheck does report an error here:
+fn vacuous<A>()
+ where i32: Foo<u32, A> //~ ERROR the trait bound `i32: Bar<u32>` is not satisfied
+{
+ // ... the original intention was to check that we don't use that
+ // vacuous where clause (which could never be satisfied) to accept
+ // the following line and then mess up calls elsewhere.
+ require::<i32, u32>();
+}
+
+fn require<A,B>()
+ where A: Bar<B>
+{
+}
+
+fn main() {
+ require::<i32, u32>();
+}