Adjust assertions in MethodMirror.source not to expect source for implicit constructors or signatur…

runtime/lib/mirrors.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "lib/invocation_mirror.h"
 #include "vm/bootstrap_natives.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
 #include "vm/exceptions.h"
@@ skipping 2019 matching lines @@
   // We handle constructors in Dart code.
   ASSERT(!func.IsConstructor());
   const AbstractType& type = AbstractType::Handle(func.result_type());
   return InstantiateType(type, instantiator);
 }
 
 
 DEFINE_NATIVE_ENTRY(MethodMirror_source, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(MirrorReference, ref, arguments->NativeArgAt(0));
   const Function& func = Function::Handle(ref.GetFunctionReferent());
+  if (func.IsImplicitConstructor() || func.IsSignatureFunction()) {
+    // We may need to handle more cases when the restrictions on mixins are
+    // relaxed. In particular we might start associating some source with the
+    // forwarding constructors when it becomes possible to specify a particular
+    // constructor from the mixin to use.
+    return Instance::null();
+  }
   const Script& script = Script::Handle(func.script());
   const TokenStream& stream = TokenStream::Handle(script.tokens());
   const TokenStream::Iterator tkit(stream, func.end_token_pos());
   intptr_t from_line;
   intptr_t from_col;
   intptr_t to_line;
   intptr_t to_col;
   script.GetTokenLocation(func.token_pos(), &from_line, &from_col);
   script.GetTokenLocation(func.end_token_pos(), &to_line, &to_col);
   intptr_t last_tok_len = String::Handle(tkit.CurrentLiteral()).Length();
   // Handle special cases for end tokens of closures (where we exclude the last
   // token):
   // (1) "foo(() => null, bar);": End token is `,', but we don't print it.
   // (2) "foo(() => null);": End token is ')`, but we don't print it.
   // (3) "var foo = () => null;": End token is `;', but in this case the token
   // semicolon belongs to the assignment so we skip it.
   if ((tkit.CurrentTokenKind() == Token::kCOMMA) ||                   // Case 1.
       (tkit.CurrentTokenKind() == Token::kRPAREN) ||                  // Case 2.
       (tkit.CurrentTokenKind() == Token::kSEMICOLON &&
        String::Handle(func.name()).Equals("<anonymous closure>"))) {  // Case 3.
     last_tok_len = 0;
   }
-  return script.GetSnippet(from_line, from_col, to_line, to_col + last_tok_len);
+  const Instance& result = Instance::Handle(
+      script.GetSnippet(from_line, from_col, to_line, to_col + last_tok_len));
+  ASSERT(!result.IsNull());
+  return result.raw();
 }
 
 
 DEFINE_NATIVE_ENTRY(TypedefMirror_referent, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(Type, type, arguments->NativeArgAt(0));
   const Class& cls = Class::Handle(type.type_class());
   const Function& sig_func = Function::Handle(cls.signature_function());
   const Class& sig_cls = Class::Handle(sig_func.signature_class());
 
   AbstractType& referent_type = AbstractType::Handle(sig_cls.DeclarationType());
@@ skipping 16 matching lines @@
 
 DEFINE_NATIVE_ENTRY(VariableMirror_type, 2) {
   GET_NON_NULL_NATIVE_ARGUMENT(MirrorReference, ref, arguments->NativeArgAt(0));
   const Field& field = Field::Handle(ref.GetFieldReferent());
   GET_NATIVE_ARGUMENT(AbstractType, instantiator, arguments->NativeArgAt(1));
   const AbstractType& type = AbstractType::Handle(field.type());
   return InstantiateType(type, instantiator);
 }
 
 }  // namespace dart