3 files changed, 35 insertions, 19 deletions
diff --git a/src/test/ui/lub-glb/empty-binder-future-compat.rs b/src/test/ui/lub-glb/empty-binder-future-compat.rs
new file mode 100644
index 00000000000..8700a88a36e
--- /dev/null
+++ b/src/test/ui/lub-glb/empty-binder-future-compat.rs
@@ -0,0 +1,22 @@
+// check-pass
+fn lt_in_fn_fn<'a: 'a>() -> fn(fn(&'a ())) {
+    |_| ()
+}
+
+
+fn foo<'a, 'b, 'lower>(v: bool)
+where
+    'a: 'lower,
+    'b: 'lower,
+{
+        // if we infer `x` to be higher ranked in the future,
+        // this would cause a type error.
+        let x = match v {
+            true => lt_in_fn_fn::<'a>(),
+            false => lt_in_fn_fn::<'b>(),
+        };
+
+        let _: fn(fn(&'lower())) = x;
+}
+
+fn main() {}
diff --git a/src/test/ui/lub-glb/empty-binders-err.rs b/src/test/ui/lub-glb/empty-binders-err.rs
index ee28dd7c97d..557480173ee 100644
--- a/src/test/ui/lub-glb/empty-binders-err.rs
+++ b/src/test/ui/lub-glb/empty-binders-err.rs
@@ -11,12 +11,10 @@ fn lt_in_contra<'a: 'a>() -> Contra<'a> {
     Contra(|_| ())
 }
 
-fn covariance<'a, 'b, 'upper, 'lower>(v: bool)
+fn covariance<'a, 'b, 'upper>(v: bool)
 where
     'upper: 'a,
     'upper: 'b,
-    'a: 'lower,
-    'b: 'lower,
 
 {
     let _: &'upper () = match v {
@@ -27,10 +25,8 @@ where
     };
 }
 
-fn contra_fn<'a, 'b, 'upper, 'lower>(v: bool)
+fn contra_fn<'a, 'b, 'lower>(v: bool)
 where
-    'upper: 'a,
-    'upper: 'b,
     'a: 'lower,
     'b: 'lower,
 
@@ -43,10 +39,8 @@ where
     };
 }
 
-fn contra_struct<'a, 'b, 'upper, 'lower>(v: bool)
+fn contra_struct<'a, 'b, 'lower>(v: bool)
 where
-    'upper: 'a,
-    'upper: 'b,
     'a: 'lower,
     'b: 'lower,
 
diff --git a/src/test/ui/lub-glb/empty-binders-err.stderr b/src/test/ui/lub-glb/empty-binders-err.stderr
index 0d5de978e43..f86f22d5e40 100644
--- a/src/test/ui/lub-glb/empty-binders-err.stderr
+++ b/src/test/ui/lub-glb/empty-binders-err.stderr
@@ -1,7 +1,7 @@
 error: lifetime may not live long enough
-  --> $DIR/empty-binders-err.rs:22:12
+  --> $DIR/empty-binders-err.rs:20:12
    |
-LL | fn covariance<'a, 'b, 'upper, 'lower>(v: bool)
+LL | fn covariance<'a, 'b, 'upper>(v: bool)
    |               --      ------ lifetime `'upper` defined here
    |               |
    |               lifetime `'a` defined here
@@ -12,9 +12,9 @@ LL |     let _: &'upper () = match v {
    = help: consider adding the following bound: `'a: 'upper`
 
 error: lifetime may not live long enough
-  --> $DIR/empty-binders-err.rs:22:12
+  --> $DIR/empty-binders-err.rs:20:12
    |
-LL | fn covariance<'a, 'b, 'upper, 'lower>(v: bool)
+LL | fn covariance<'a, 'b, 'upper>(v: bool)
    |                   --  ------ lifetime `'upper` defined here
    |                   |
    |                   lifetime `'b` defined here
@@ -30,10 +30,10 @@ help: the following changes may resolve your lifetime errors
    = help: add bound `'b: 'upper`
 
 error: lifetime may not live long enough
-  --> $DIR/empty-binders-err.rs:39:12
+  --> $DIR/empty-binders-err.rs:35:12
    |
-LL | fn contra_fn<'a, 'b, 'upper, 'lower>(v: bool)
-   |              --              ------ lifetime `'lower` defined here
+LL | fn contra_fn<'a, 'b, 'lower>(v: bool)
+   |              --      ------ lifetime `'lower` defined here
    |              |
    |              lifetime `'a` defined here
 ...
@@ -43,10 +43,10 @@ LL |     let _: fn(&'lower ()) = match v {
    = help: consider adding the following bound: `'lower: 'a`
 
 error: lifetime may not live long enough
-  --> $DIR/empty-binders-err.rs:54:12
+  --> $DIR/empty-binders-err.rs:48:12
    |
-LL | fn contra_struct<'a, 'b, 'upper, 'lower>(v: bool)
-   |                  --              ------ lifetime `'lower` defined here
+LL | fn contra_struct<'a, 'b, 'lower>(v: bool)
+   |                  --      ------ lifetime `'lower` defined here
    |                  |
    |                  lifetime `'a` defined here
 ...