[hot reload] Give a better error message when changing between a regular class and a typedef.

runtime/vm/isolate_reload_test.cc

Index: runtime/vm/isolate_reload_test.cc
diff --git a/runtime/vm/isolate_reload_test.cc b/runtime/vm/isolate_reload_test.cc
index be2a2f30049f09ce97ae31a53f1f90c9a25abca8..d34d108b8212e7b548798a20c4900e51fd7da011 100644
--- a/runtime/vm/isolate_reload_test.cc
+++ b/runtime/vm/isolate_reload_test.cc
@@ -3427,6 +3427,80 @@ TEST_CASE(IsolateREload_RunNewFieldInitialiazersSuperClass) {
   EXPECT_STREQ("right", SimpleInvokeStr(lib, "main"));
 }
 
+
+TEST_CASE(IsolateReload_TypedefToNotTypedef) {
+  const char* kScript =
+      "typedef bool Predicate(dynamic x);\n"
+      "main() {\n"
+      "  return (42 is Predicate).toString();\n"
+      "}\n";
+
+  Dart_Handle lib = TestCase::LoadTestScript(kScript, NULL);
+  EXPECT_VALID(lib);
+  EXPECT_STREQ("false", SimpleInvokeStr(lib, "main"));
+
+  const char* kReloadScript =
+      "class Predicate {\n"
+      "  bool call(dynamic x) { return false; }\n"
+      "}\n"
+      "main() {\n"
+      "  return (42 is Predicate).toString();\n"
+      "}\n";
+
+  Dart_Handle result = TestCase::ReloadTestScript(kReloadScript);
+  EXPECT_ERROR(result,
+               "Typedef class cannot be redefined to be a non-typedef class");
+}
+
+
+TEST_CASE(IsolateReload_NotTypedefToTypedef) {
+  const char* kScript =
+      "class Predicate {\n"
+      "  bool call(dynamic x) { return false; }\n"
+      "}\n"
+      "main() {\n"
+      "  return (42 is Predicate).toString();\n"
+      "}\n";
+
+  Dart_Handle lib = TestCase::LoadTestScript(kScript, NULL);
+  EXPECT_VALID(lib);
+  EXPECT_STREQ("false", SimpleInvokeStr(lib, "main"));
+
+  const char* kReloadScript =
+      "typedef bool Predicate(dynamic x);\n"
+      "main() {\n"
+      "  return (42 is Predicate).toString();\n"
+      "}\n";
+
+  Dart_Handle result = TestCase::ReloadTestScript(kReloadScript);
+  EXPECT_ERROR(result, "Class cannot be redefined to be a typedef class");
+}
+
+
+TEST_CASE(IsolateReload_TypedefAddParameter) {
+  const char* kScript =
+      "typedef bool Predicate(dynamic x);\n"
+      "main() {\n"
+      "  bool foo(x) => true;\n"
+      "  return (foo is Predicate).toString();\n"
+      "}\n";
+
+  Dart_Handle lib = TestCase::LoadTestScript(kScript, NULL);
+  EXPECT_VALID(lib);
+  EXPECT_STREQ("true", SimpleInvokeStr(lib, "main"));
+
+  const char* kReloadScript =
+      "typedef bool Predicate(dynamic x, dynamic y);\n"
+      "main() {\n"
+      "  bool foo(x) => true;\n"
+      "  return (foo is Predicate).toString();\n"
+      "}\n";
+
+  Dart_Handle result = TestCase::ReloadTestScript(kReloadScript);
+  EXPECT_VALID(result);
+  EXPECT_STREQ("false", SimpleInvokeStr(lib, "main"));
+}
+
 #endif  // !PRODUCT
 
 }  // namespace dart