Rename Session::span_diagnostic as Session::dcx.

compiler/rustc_const_eval/src/transform/validate.rs

@@ -130,7 +130,7 @@ impl<'a, 'tcx> CfgChecker<'a, 'tcx> {
         let span = self.body.source_info(location).span;
         // We use `span_delayed_bug` as we might see broken MIR when other errors have already
         // occurred.
-        self.tcx.sess.diagnostic().span_delayed_bug(
+        self.tcx.sess.dcx().span_delayed_bug(
             span,
             format!(
                 "broken MIR in {:?} ({}) at {:?}:\n{}",
@@ -571,7 +571,7 @@ impl<'a, 'tcx> Visitor<'tcx> for CfgChecker<'a, 'tcx> {
 
     fn visit_source_scope(&mut self, scope: SourceScope) {
         if self.body.source_scopes.get(scope).is_none() {
-            self.tcx.sess.diagnostic().span_delayed_bug(
+            self.tcx.sess.dcx().span_delayed_bug(
                 self.body.span,
                 format!(
                     "broken MIR in {:?} ({}):\ninvalid source scope {:?}",