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-rw-r--r--tests/ui/regions/regions-infer-covariance-due-to-decl.rs26
1 files changed, 26 insertions, 0 deletions
diff --git a/tests/ui/regions/regions-infer-covariance-due-to-decl.rs b/tests/ui/regions/regions-infer-covariance-due-to-decl.rs
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+++ b/tests/ui/regions/regions-infer-covariance-due-to-decl.rs
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+// Test that a type which is covariant with respect to its region
+// parameter yields an error when used in a contravariant way.
+//
+// Note: see variance-regions-*.rs for the tests that check that the
+// variance inference works in the first place.
+
+use std::marker;
+
+struct Covariant<'a> {
+ marker: marker::PhantomData<fn(&'a ())>
+}
+
+fn use_<'short,'long>(c: Covariant<'long>,
+ s: &'short isize,
+ l: &'long isize,
+ _where:Option<&'short &'long ()>) {
+
+ // Test whether Covariant<'long> <: Covariant<'short>. Since
+ // 'short <= 'long, this would be true if the Covariant type were
+ // contravariant with respect to its parameter 'a.
+
+ let _: Covariant<'short> = c;
+ //~^ ERROR lifetime may not live long enough
+}
+
+fn main() {}