Fix crashes due to attempts to create an identifier name containing the word <bottom>. Likely there…

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
diff --git a/runtime/vm/parser.cc b/runtime/vm/parser.cc
index cb9c620101ec318ff2baffb48bf4f5a698cea49e..970f75dbd9a2930b60f05ffe00f0d21f60a07395 100644
--- a/runtime/vm/parser.cc
+++ b/runtime/vm/parser.cc
@@ -61,6 +61,7 @@ DEFINE_FLAG(bool, assert_initializer, false,
 
 DECLARE_FLAG(bool, profile_vm);
 DECLARE_FLAG(bool, trace_service);
+DECLARE_FLAG(bool, ignore_patch_signature_mismatch);
 
 // Quick access to the current thread, isolate and zone.
 #define T (thread())
@@ -4731,35 +4732,37 @@ void Parser::ParseClassDeclaration(const GrowableObjectArray& pending_classes,
                   "class '%s' must be patched with identical type parameters",
                   class_name.ToCString());
     }
-    TypeParameter& new_type_param = TypeParameter::Handle(Z);
-    TypeParameter& orig_type_param = TypeParameter::Handle(Z);
-    String& new_name = String::Handle(Z);
-    String& orig_name = String::Handle(Z);
-    AbstractType& new_bound = AbstractType::Handle(Z);
-    AbstractType& orig_bound = AbstractType::Handle(Z);
-    for (int i = 0; i < new_type_params_count; i++) {
-      new_type_param ^= new_type_parameters.TypeAt(i);
-      orig_type_param ^= orig_type_parameters.TypeAt(i);
-      new_name = new_type_param.name();
-      orig_name = orig_type_param.name();
-      if (!new_name.Equals(orig_name)) {
-        ReportError(new_type_param.token_pos(),
-                    "type parameter '%s' of patch class '%s' does not match "
-                    "original type parameter '%s'",
-                    new_name.ToCString(),
-                    class_name.ToCString(),
-                    orig_name.ToCString());
-      }
-      new_bound = new_type_param.bound();
-      orig_bound = orig_type_param.bound();
-      if (!new_bound.Equals(orig_bound)) {
-        ReportError(new_type_param.token_pos(),
-                    "bound '%s' of type parameter '%s' of patch class '%s' "
-                    "does not match original type parameter bound '%s'",
-                    String::Handle(new_bound.UserVisibleName()).ToCString(),
-                    new_name.ToCString(),
-                    class_name.ToCString(),
-                    String::Handle(orig_bound.UserVisibleName()).ToCString());
+    if (!FLAG_ignore_patch_signature_mismatch) {
+      TypeParameter& new_type_param = TypeParameter::Handle(Z);
+      TypeParameter& orig_type_param = TypeParameter::Handle(Z);
+      String& new_name = String::Handle(Z);
+      String& orig_name = String::Handle(Z);
+      AbstractType& new_bound = AbstractType::Handle(Z);
+      AbstractType& orig_bound = AbstractType::Handle(Z);
+      for (int i = 0; i < new_type_params_count; i++) {
+        new_type_param ^= new_type_parameters.TypeAt(i);
+        orig_type_param ^= orig_type_parameters.TypeAt(i);
+        new_name = new_type_param.name();
+        orig_name = orig_type_param.name();
+        if (!new_name.Equals(orig_name)) {
+          ReportError(new_type_param.token_pos(),
+                      "type parameter '%s' of patch class '%s' does not match "
+                      "original type parameter '%s'",
+                      new_name.ToCString(),
+                      class_name.ToCString(),
+                      orig_name.ToCString());
+        }
+        new_bound = new_type_param.bound();
+        orig_bound = orig_type_param.bound();
+        if (!new_bound.Equals(orig_bound)) {
+          ReportError(new_type_param.token_pos(),
+                      "bound '%s' of type parameter '%s' of patch class '%s' "
+                      "does not match original type parameter bound '%s'",
+                      String::Handle(new_bound.UserVisibleName()).ToCString(),
+                      new_name.ToCString(),
+                      class_name.ToCString(),
+                      String::Handle(orig_bound.UserVisibleName()).ToCString());
+        }
       }
     }
     cls.set_type_parameters(orig_type_parameters);