[modules] Detect and throw exceptions for cyclic dependencies

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index b569d457ef7ed75b4a4b13cd8836841c4fffa304..874a59fad702eb17c1dce1059a4288438503d22c 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -48,6 +48,7 @@
 #include "src/lookup.h"
 #include "src/macro-assembler.h"
 #include "src/messages.h"
+#include "src/module-resolve-set-inl.h"
 #include "src/objects-body-descriptors-inl.h"
 #include "src/property-descriptor.h"
 #include "src/prototype.h"
@@ -19629,19 +19630,37 @@ Handle<Object> Module::LoadImport(Handle<Module> module, Handle<String> name,
 }
 
 MaybeHandle<Cell> Module::ResolveImport(Handle<Module> module,
-                                        Handle<String> name,
-                                        int module_request) {
+                                        Handle<String> name, int module_request,
+                                        Module::ResolveSet* resolve_set,
+                                        Zone* zone) {
   Isolate* isolate = module->GetIsolate();
   Handle<Module> requested_module(
       Module::cast(module->requested_modules()->get(module_request)), isolate);
-  return Module::ResolveExport(requested_module, name);
+  return Module::ResolveExport(requested_module, name, resolve_set, zone);
 }
 
 MaybeHandle<Cell> Module::ResolveExport(Handle<Module> module,
-                                        Handle<String> name) {
-  // TODO(neis): Detect cycles.
-
+                                        Handle<String> name,
+                                        Module::ResolveSet* resolve_set,
+                                        Zone* zone) {
   Isolate* isolate = module->GetIsolate();
+
+  auto it = resolve_set->find(module);
+  if (it != resolve_set->end()) {
+    auto& name_set = it->second;
+    if (name_set->count(name)) {
+      THROW_NEW_ERROR(isolate,
+                      NewSyntaxError(MessageTemplate::kCyclicModuleDependency),
+                      Cell);
+    }
+    name_set->insert(name);
+  } else {
+    UnorderedStringSet* name_set =
+        new (zone->New(sizeof(UnorderedStringSet))) UnorderedStringSet(zone);
+    name_set->insert(name);
+    resolve_set->insert({module, name_set});
+  }
+
   Handle<Object> object(module->exports()->Lookup(name), isolate);
 
   if (object->IsCell()) {
@@ -19656,7 +19675,8 @@ MaybeHandle<Cell> Module::ResolveExport(Handle<Module> module,
     Handle<String> import_name(String::cast(entry->import_name()), isolate);
 
     Handle<Cell> cell;
-    if (!ResolveImport(module, import_name, module_request).ToHandle(&cell)) {
+    if (!ResolveImport(module, import_name, module_request, resolve_set, zone)
+             .ToHandle(&cell)) {
       return MaybeHandle<Cell>();
     }