Merging upstream version 1.68.2+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 29 insertions, 0 deletions

diff --git a/tests/ui/nll/polonius/subset-relations.rs b/tests/ui/nll/polonius/subset-relations.rs
new file mode 100644
index 000000000..f223ab177
--- /dev/null
+++ b/tests/ui/nll/polonius/subset-relations.rs
@@ -0,0 +1,29 @@
+// Checks that Polonius can compute cases of universal regions errors:
+// "illegal subset relation errors", cases where analysis finds that
+// two free regions outlive each other, without any evidence that this
+// relation holds.
+
+// compile-flags: -Z polonius
+
+// returning `y` requires that `'b: 'a`, but it's not known to be true
+fn missing_subset<'a, 'b>(x: &'a u32, y: &'b u32) -> &'a u32 {
+    y //~ ERROR
+}
+
+// `'b: 'a` is explicitly declared
+fn valid_subset<'a, 'b: 'a>(x: &'a u32, y: &'b u32) -> &'a u32 {
+    y
+}
+
+// because of `x`, it is implied that `'b: 'a` holds
+fn implied_bounds_subset<'a, 'b>(x: &'a &'b mut u32) -> &'a u32 {
+    x
+}
+
+// `'b: 'a` is declared, and `'a: 'c` is known via implied bounds:
+// `'b: 'c` is therefore known to hold transitively
+fn transitively_valid_subset<'a, 'b: 'a, 'c>(x: &'c &'a u32, y: &'b u32) -> &'c u32  {
+    y
+}
+
+fn main() {}