mbe: Continue after error from unsafe applied to rules that don't support it

Author: joshtriplett

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -739,11 +739,8 @@ pub fn compile_declarative_macro(
                     .emit();
             }
             if unsafe_rule {
-                let err = sess.dcx().struct_span_err(
-                    unsafe_keyword_span,
-                    "`unsafe` is only supported on `attr` rules",
-                );
-                return dummy_syn_ext(err.emit());
+                sess.dcx()
+                    .span_err(unsafe_keyword_span, "`unsafe` is only supported on `attr` rules");
             }
             if let Some(guar) = check_no_eof(sess, &p, "expected `()` after `derive`") {
                 return dummy_syn_ext(guar);
@@ -771,11 +768,8 @@ pub fn compile_declarative_macro(
         } else {
             kinds |= MacroKinds::BANG;
             if unsafe_rule {
-                let err = sess.dcx().struct_span_err(
-                    unsafe_keyword_span,
-                    "`unsafe` is only supported on `attr` rules",
-                );
-                return dummy_syn_ext(err.emit());
+                sess.dcx()
+                    .span_err(unsafe_keyword_span, "`unsafe` is only supported on `attr` rules");
             }
             (None, false)
         };