Sad

compiler/rustc_typeck/src/check/inherited.rs

@@ -37,6 +37,7 @@ pub struct Inherited<'a, 'tcx> {
 
     // Some additional `Sized` obligations badly affect type inference.
     // These obligations are added in a later stage of typeck.
+    // Removing these may also cause additional complications, see #101066.
     pub(super) deferred_sized_obligations:
         RefCell<Vec<(Ty<'tcx>, Span, traits::ObligationCauseCode<'tcx>)>>,
 

src/test/ui/coercion/issue-101066.rs

@@ -0,0 +1,16 @@
+// check-pass
+
+use std::convert::TryFrom;
+
+pub trait FieldElement {
+    type Integer: TryFrom<usize, Error = std::num::TryFromIntError>;
+
+    fn valid_integer_try_from<N>(i: N) -> Result<Self::Integer, ()>
+    where
+        Self::Integer: TryFrom<N>,
+    {
+        Self::Integer::try_from(i).map_err(|_| ())
+    }
+}
+
+fn main() {}