Take ocx by move for pending obligations

compiler/rustc_hir_analysis/src/autoderef.rs

@@ -188,7 +188,7 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
             return None;
         }
 
-        Some((normalized_ty, ocx.pending_obligations()))
+        Some((normalized_ty, ocx.into_pending_obligations()))
     }
 
     /// Returns the final type we ended up with, which may be an inference

compiler/rustc_hir_typeck/src/coercion.rs

@@ -165,7 +165,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                     let ocx = ObligationCtxt::new(self);
                     ocx.register_obligations(obligations);
                     if ocx.select_where_possible().is_empty() {
-                        Ok(InferOk { value, obligations: ocx.pending_obligations() })
+                        Ok(InferOk { value, obligations: ocx.into_pending_obligations() })
                     } else {
                         Err(TypeError::Mismatch)
                     }
@@ -633,7 +633,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                     if !ocx.select_where_possible().is_empty() {
                         return Err(TypeError::Mismatch);
                     }
-                    coercion.obligations.extend(ocx.pending_obligations());
+                    coercion.obligations.extend(ocx.into_pending_obligations());
                     continue;
                 }
                 _ => {

compiler/rustc_trait_selection/src/traits/engine.rs

@@ -195,8 +195,15 @@ impl<'a, 'tcx> ObligationCtxt<'a, 'tcx> {
         self.engine.borrow_mut().select_all_or_error(self.infcx)
     }
 
+    /// Returns the not-yet-processed and stalled obligations from the
+    /// `ObligationCtxt`.
+    ///
+    /// Takes ownership of the context as doing operations such as
+    /// [`ObligationCtxt::eq`] afterwards will result in other obligations
+    /// getting ignored. You can make a new `ObligationCtxt` if this
+    /// needs to be done in a loop, for example.
     #[must_use]
-    pub fn pending_obligations(&self) -> Vec<PredicateObligation<'tcx>> {
+    pub fn into_pending_obligations(self) -> Vec<PredicateObligation<'tcx>> {
         self.engine.borrow().pending_obligations()
     }