Convert a delayed bug to a bug.

This is never hit in the test suite.

At some point the check should be removed entirely. There are a million
places in the compiler where an empty symbol doesn't make sense, so a
check of this nature has almost zero value. But I'll leave it in place
for now just in case it gets hit by fuzzing or in the wild.

Author: nnethercote

compiler/rustc_hir_typeck/src/expr.rs

@@ -2933,7 +2933,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
 
         let guar = if field.name == kw::Empty {
-            self.dcx().span_delayed_bug(field.span, "field name with no name")
+            self.dcx().span_bug(field.span, "field name with no name")
         } else if self.method_exists_for_diagnostic(
             field,
             base_ty,