add test

tests/ui/implied-bounds/from-trait-impl.rs

@@ -0,0 +1,21 @@
+// Foo<Vec<X>> shouldn't imply X: 'static.
+// We don't use region constraints from trait impls in implied bounds.
+
+trait Trait {
+    type Assoc;
+}
+
+impl<X: 'static> Trait for Vec<X> {
+    type Assoc = ();
+}
+
+struct Foo<T: Trait>(T)
+where
+    T::Assoc: 'static, // any predicate naming T::Assoc
+;
+
+fn foo<X>(_: Foo<Vec<X>>) {}
+//~^ ERROR `X` may not live long enough
+//~| ERROR `X` may not live long enough
+
+fn main() {}

tests/ui/implied-bounds/from-trait-impl.stderr

@@ -0,0 +1,31 @@
+error[E0310]: the parameter type `X` may not live long enough
+  --> $DIR/from-trait-impl.rs:17:1
+   |
+LL | fn foo<X>(_: Foo<Vec<X>>) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^
+   | |
+   | the parameter type `X` must be valid for the static lifetime...
+   | ...so that the type `X` will meet its required lifetime bounds
+   |
+help: consider adding an explicit lifetime bound
+   |
+LL | fn foo<X: 'static>(_: Foo<Vec<X>>) {}
+   |         +++++++++
+
+error[E0310]: the parameter type `X` may not live long enough
+  --> $DIR/from-trait-impl.rs:17:14
+   |
+LL | fn foo<X>(_: Foo<Vec<X>>) {}
+   |              ^^^^^^^^^^^
+   |              |
+   |              the parameter type `X` must be valid for the static lifetime...
+   |              ...so that the type `X` will meet its required lifetime bounds
+   |
+help: consider adding an explicit lifetime bound
+   |
+LL | fn foo<X: 'static>(_: Foo<Vec<X>>) {}
+   |         +++++++++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0310`.