Added some debug logging.

src/librustc_mir/borrow_check/move_errors.rs

@@ -221,6 +221,7 @@ impl<'a, 'gcx, 'tcx> MirBorrowckCtxt<'a, 'gcx, 'tcx> {
                 | GroupedMoveError::OtherIllegalMove { span, ref kind } => (span, kind),
             };
             let origin = Origin::Mir;
+            debug!("report: span={:?}, kind={:?}", span, kind);
             (
                 match kind {
                     IllegalMoveOriginKind::Static => {
@@ -262,6 +263,10 @@ impl<'a, 'gcx, 'tcx> MirBorrowckCtxt<'a, 'gcx, 'tcx> {
                                     }
                                     None => bug!("closure kind not inferred by borrowck"),
                                 };
+                                debug!("report: closure_kind_ty={:?} closure_kind={:?} \
+                                       place_description={:?}", closure_kind_ty, closure_kind,
+                                       place_description);
+
                                 self.tcx.cannot_move_out_of(span, place_description, origin)
                             }
                             _ => self

src/librustc_mir/borrow_check/mutability_errors.rs

@@ -36,10 +36,18 @@ impl<'a, 'gcx, 'tcx> MirBorrowckCtxt<'a, 'gcx, 'tcx> {
         error_access: AccessKind,
         location: Location,
     ) {
+        debug!(
+            "report_mutability_error(\
+                access_place={:?}, span={:?}, the_place_err={:?}, error_access={:?}, location={:?},\
+            )",
+            access_place, span, the_place_err, error_access, location,
+        );
+
         let mut err;
         let item_msg;
         let reason;
         let access_place_desc = self.describe_place(access_place);
+        debug!("report_mutability_error: access_place_desc={:?}", access_place_desc);
 
         match the_place_err {
             Place::Local(local) => {
@@ -155,6 +163,8 @@ impl<'a, 'gcx, 'tcx> MirBorrowckCtxt<'a, 'gcx, 'tcx> {
             }) => bug!("Unexpected immutable place."),
         }
 
+        debug!("report_mutability_error: item_msg={:?}, reason={:?}", item_msg, reason);
+
         // `act` and `acted_on` are strings that let us abstract over
         // the verbs used in some diagnostic messages.
         let act;
@@ -199,6 +209,8 @@ impl<'a, 'gcx, 'tcx> MirBorrowckCtxt<'a, 'gcx, 'tcx> {
             }
         };
 
+        debug!("report_mutability_error: act={:?}, acted_on={:?}", act, acted_on);
+
         match the_place_err {
             // We want to suggest users use `let mut` for local (user
             // variable) mutations...