add test from modcholesky breakage

Author: lqd

tests/ui/wf/wf-where-clauses-pre-normalization.rs

@@ -0,0 +1,20 @@
+// This is a test, extracted from `modcholesky`, that used to pass wfcheck because we checked
+// well-formedness of where-clauses *after* normalization. We generally want to move to always check
+// WF pre-normalization.
+
+pub struct View<A>(A);
+pub trait Data {
+    type Elem;
+}
+impl<'a, A> Data for View<&'a A> {
+    type Elem = A;
+}
+
+pub fn repro<'a, T>()
+where
+    <View<&'a T> as Data>::Elem: Sized,
+    //~^ ERROR: the parameter type `T` may not live long enough
+{
+}
+
+fn main() {}

tests/ui/wf/wf-where-clauses-pre-normalization.stderr

@@ -0,0 +1,17 @@
+error[E0309]: the parameter type `T` may not live long enough
+  --> $DIR/wf-where-clauses-pre-normalization.rs:15:34
+   |
+LL | pub fn repro<'a, T>()
+   |              -- the parameter type `T` must be valid for the lifetime `'a` as defined here...
+LL | where
+LL |     <View<&'a T> as Data>::Elem: Sized,
+   |                                  ^^^^^ ...so that the reference type `&'a T` does not outlive the data it points at
+   |
+help: consider adding an explicit lifetime bound
+   |
+LL | pub fn repro<'a, T: 'a>()
+   |                   ++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0309`.