Read platform.dill in the VM.

runtime/vm/kernel_reader.cc

Index: runtime/vm/kernel_reader.cc
diff --git a/runtime/vm/kernel_reader.cc b/runtime/vm/kernel_reader.cc
index 231300e595be74842e241850bdf2144a308c403b..d896becf14c95de000e172b4ca637fbdf0ede750 100644
--- a/runtime/vm/kernel_reader.cc
+++ b/runtime/vm/kernel_reader.cc
@@ -135,12 +135,39 @@ Object& KernelReader::ReadProgram() {
 
     if (ClassFinalizer::ProcessPendingClasses(/*from_kernel=*/true)) {
       CanonicalName* main = program_->main_method();
-      dart::Library& library = LookupLibrary(main->EnclosingName());
+      if (main == NULL) {
+        return dart::Library::Handle(Z);
+      }
 
+      CanonicalName* main_library = main->EnclosingName();
+      dart::Library& library = LookupLibrary(main_library);
       // Sanity check that we can find the main entrypoint.
       Object& main_obj = Object::Handle(
           Z, library.LookupObjectAllowPrivate(H.DartSymbol("main")));
       ASSERT(!main_obj.IsNull());
+
+      // There is a function _getMainClosure in dart:_builtin that returns the

[Kevin Millikin (Google), 2017/03/31 10:05:42]

I'm aware that this is ugly.  It would be better to either get rid of
_getMainClosure and just look up main in the root library, or else make
_getMainClosure a native so it's OK to have a 'magical' implementation.

[Vyacheslav Egorov (Google), 2017/04/05 12:21:23]

We would also need to come up with solution for the future in which the flow
graph builder is streaming from Binary and AST nodes do not exist anymore.

[Kevin Millikin (Google), 2017/04/25 18:20:29]

I know, and those changes started landing before this one.  I've updated this to
work by special casing StaticGet what doesn't come from the binary.

Agreed we need a better solution for the long term.

+      // main procedure.  Since the platform libraries are compiled before the
+      // program script, this function is patched here.
+      dart::Library& builtin_library =
+          dart::Library::Handle(Z, I->object_store()->builtin_library());
+      Function& to_patch =
+          Function::Handle(builtin_library.LookupFunctionAllowPrivate(

[kustermann, 2017/04/05 11:47:07]

Handle(Z, 

[Kevin Millikin (Google), 2017/04/25 18:20:29]

Done.

+              dart::String::Handle(dart::String::New("_getMainClosure"))));
+
+      // Build a canonical name tree instead of sharing main's canonical name.
+      CanonicalName* name = CanonicalName::NewRoot();

[kustermann, 2017/04/05 11:47:07]

This will leak [name], right?

Please add a comment about it.

+      name = name->AddChild(new String(main_library->name()->buffer(),
+                                       main_library->name()->size()));

[kustermann, 2017/04/05 11:47:07]

This "new String()" will never be freed afaik! (also for the other cases below).

Please add a comment about it.

[Kevin Millikin (Google), 2017/04/25 18:20:29]

Comment added that we are leaking the whole body.

+      CanonicalName* kind = main->parent();
+      name = name->AddChild(
+          new String(kind->name()->buffer(), kind->name()->size()));
+      name = name->AddChild(new String("main"));
+
+      Procedure* procedure =
+          reinterpret_cast<Procedure*>(to_patch.kernel_function());
+      procedure->function()->set_body(new ReturnStatement(new StaticGet(name)));

[kustermann, 2017/04/05 11:47:07]

I assume the function has already a body (like nsm call) and you replace it with
the static tearoff, right?

In that case: set_body() will hit an ASSERT because it uses "Child<Statement>
body_" and

                                                    
 138 template <typename T>
 ...
 139 class Child {
 147   T*& operator=(T* value) {
 148     ASSERT(pointer_ == NULL);
 149     return pointer_ = value;
 150   }

[Kevin Millikin (Google), 2017/04/25 18:20:29]

It doesn't have a body, it's treated as if it were external by special casing in
the front end.

+
       return library;
     }
   }
@@ -211,7 +238,7 @@ void KernelReader::ReadLibrary(Library* kernel_library) {
   toplevel_class.SetFunctions(Array::Handle(MakeFunctionsArray()));
 
   const GrowableObjectArray& classes =
-      GrowableObjectArray::Handle(I->object_store()->pending_classes());
+      GrowableObjectArray::Handle(Z, I->object_store()->pending_classes());
 
   // Load all classes.
   for (intptr_t i = 0; i < kernel_library->classes().length(); i++) {