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Diffstat (limited to 'tests/ui/cross/cross-fn-cache-hole.rs')
-rw-r--r-- | tests/ui/cross/cross-fn-cache-hole.rs | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/tests/ui/cross/cross-fn-cache-hole.rs b/tests/ui/cross/cross-fn-cache-hole.rs new file mode 100644 index 000000000..c38a5001a --- /dev/null +++ b/tests/ui/cross/cross-fn-cache-hole.rs @@ -0,0 +1,31 @@ +// 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>(); +} |