Issue #1624 - Add missing error handling and bail on null specifier.modulefix

12 files changed, 232 insertions, 79 deletions

diff --git a/dom/script/ScriptLoader.cpp b/dom/script/ScriptLoader.cpp
index 5b7bea8d22..e11511eb92 100644
--- a/dom/script/ScriptLoader.cpp
+++ b/dom/script/ScriptLoader.cpp
@@ -599,38 +599,31 @@ ScriptLoader::CreateModuleScript(ModuleLoadRequest* aRequest)
   return rv;
 }
 
-static bool
-CreateTypeError(JSContext* aCx, ModuleScript* aScript, const nsString& aMessage,
-                JS::MutableHandle<JS::Value> aError)
+static nsresult
+HandleResolveFailure(JSContext* aCx, ModuleScript* aScript,
+                     const nsAString& aSpecifier,
+                     uint32_t aLineNumber, uint32_t aColumnNumber)
 {
-  JS::Rooted<JSObject*> module(aCx, aScript->ModuleRecord());
-  JS::Rooted<JSScript*> script(aCx, JS::GetModuleScript(aCx, module));
+  nsAutoCString url;
+  aScript->BaseURL()->GetAsciiSpec(url);
+
   JS::Rooted<JSString*> filename(aCx);
-  filename = JS_NewStringCopyZ(aCx, JS_GetScriptFilename(script));
+  filename = JS_NewStringCopyZ(aCx, url.get());
   if (!filename) {
-    return false;
-  }
-
-  JS::Rooted<JSString*> message(aCx, JS_NewUCStringCopyZ(aCx, aMessage.get()));
-  if (!message) {
-    return false;
+    return NS_ERROR_OUT_OF_MEMORY;
   }
 
-  return JS::CreateError(aCx, JSEXN_TYPEERR, nullptr, filename, 0, 0, nullptr,
-                         message, aError);
-}
-
-static nsresult
-HandleResolveFailure(JSContext* aCx, ModuleScript* aScript,
-                     const nsAString& aSpecifier)
-{
-  // TODO: How can we get the line number of the failed import?
-
   nsAutoString message(NS_LITERAL_STRING("Error resolving module specifier: "));
   message.Append(aSpecifier);
 
+  JS::Rooted<JSString*> string(aCx, JS_NewUCStringCopyZ(aCx, message.get()));
+  if (!string) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
   JS::Rooted<JS::Value> error(aCx);
-  if (!CreateTypeError(aCx, aScript, message, &error)) {
+  if (!JS::CreateError(aCx, JSEXN_TYPEERR, nullptr, filename, aLineNumber,
+                       aColumnNumber, nullptr, string, &error)) {
     return NS_ERROR_OUT_OF_MEMORY;
   }
 
@@ -685,28 +678,37 @@ ResolveRequestedModules(ModuleLoadRequest* aRequest, nsCOMArray<nsIURI>* aUrlsOu
 
   JSContext* cx = jsapi.cx();
   JS::Rooted<JSObject*> moduleRecord(cx, ms->ModuleRecord());
-  JS::Rooted<JSObject*> specifiers(cx, JS::GetRequestedModules(cx, moduleRecord));
+  JS::Rooted<JSObject*> requestedModules(cx);
+  requestedModules = JS::GetRequestedModules(cx, moduleRecord);
+  MOZ_ASSERT(requestedModules);
 
   uint32_t length;
-  if (!JS_GetArrayLength(cx, specifiers, &length)) {
+  if (!JS_GetArrayLength(cx, requestedModules, &length)) {
     return NS_ERROR_FAILURE;
   }
 
-  JS::Rooted<JS::Value> val(cx);
+  JS::Rooted<JS::Value> element(cx);
   for (uint32_t i = 0; i < length; i++) {
-    if (!JS_GetElement(cx, specifiers, i, &val)) {
+    if (!JS_GetElement(cx, requestedModules, i, &element)) {
       return NS_ERROR_FAILURE;
     }
 
+    JS::Rooted<JSString*> str(cx, JS::GetRequestedModuleSpecifier(cx, element));
+    MOZ_ASSERT(str);
+
     nsAutoJSString specifier;
-    if (!specifier.init(cx, val)) {
+    if (!specifier.init(cx, str)) {
       return NS_ERROR_FAILURE;
     }
 
     // Let url be the result of resolving a module specifier given module script and requested.
     nsCOMPtr<nsIURI> uri = ResolveModuleSpecifier(ms, specifier);
     if (!uri) {
-      nsresult rv = HandleResolveFailure(cx, ms, specifier);
+      uint32_t lineNumber = 0;
+      uint32_t columnNumber = 0;
+      JS::GetRequestedModuleSourcePos(cx, element, &lineNumber, &columnNumber);
+
+      nsresult rv = HandleResolveFailure(cx, ms, specifier, lineNumber, columnNumber);
       NS_ENSURE_SUCCESS(rv, rv);
       return NS_ERROR_FAILURE;
     }
@@ -806,6 +808,11 @@ HostResolveImportedModule(JSContext* aCx, JS::Handle<JSObject*> aModule,
   auto script = static_cast<ModuleScript*>(value.toPrivate());
   MOZ_ASSERT(script->ModuleRecord() == aModule);
 
+  // FIXME: in-line module scripts apparently pass a null specifier?
+  // At least make sure that doesn't crash the browser.
+  if (!aSpecifier)
+    return nullptr;
+    
   // Let url be the result of resolving a module specifier given referencing
   // module script and specifier.
   nsAutoJSString string;
diff --git a/js/public/Class.h b/js/public/Class.h
index 9cb3778920..094e4a7ed7 100644
--- a/js/public/Class.h
+++ b/js/public/Class.h
@@ -778,7 +778,7 @@ struct JSClass {
 // application.
 #define JSCLASS_GLOBAL_APPLICATION_SLOTS 5
 #define JSCLASS_GLOBAL_SLOT_COUNT                                             \
-    (JSCLASS_GLOBAL_APPLICATION_SLOTS + JSProto_LIMIT * 2 + 45)
+    (JSCLASS_GLOBAL_APPLICATION_SLOTS + JSProto_LIMIT * 2 + 46)
 #define JSCLASS_GLOBAL_FLAGS_WITH_SLOTS(n)                                    \
     (JSCLASS_IS_GLOBAL | JSCLASS_HAS_RESERVED_SLOTS(JSCLASS_GLOBAL_SLOT_COUNT + (n)))
 #define JSCLASS_GLOBAL_FLAGS                                                  \
diff --git a/js/src/builtin/Module.js b/js/src/builtin/Module.js
index 355303d44d..a7758484eb 100644
--- a/js/src/builtin/Module.js
+++ b/js/src/builtin/Module.js
@@ -363,7 +363,7 @@ function InnerModuleInstantiation(module, stack, index)
     // Step 9
     let requestedModules = module.requestedModules;
     for (let i = 0; i < requestedModules.length; i++) {
-        let required = requestedModules[i];
+        let required = requestedModules[i].moduleSpecifier;
         let requiredModule = CallModuleResolveHook(module, required, MODULE_STATUS_UNINSTANTIATED);
 
         index = InnerModuleInstantiation(requiredModule, stack, index);
@@ -591,7 +591,7 @@ function InnerModuleEvaluation(module, stack, index)
     // Step 10
     let requestedModules = module.requestedModules;
     for (let i = 0; i < requestedModules.length; i++) {
-        let required = requestedModules[i];
+        let required = requestedModules[i].moduleSpecifier;
         let requiredModule =
             CallModuleResolveHook(module, required, MODULE_STATUS_INSTANTIATED);
 
diff --git a/js/src/builtin/ModuleObject.cpp b/js/src/builtin/ModuleObject.cpp
index 2790b1c444..a09dd77dde 100644
--- a/js/src/builtin/ModuleObject.cpp
+++ b/js/src/builtin/ModuleObject.cpp
@@ -125,7 +125,7 @@ GlobalObject::initImportEntryProto(JSContext* cx, Handle<GlobalObject*> global)
     if (!DefinePropertiesAndFunctions(cx, proto, protoAccessors, nullptr))
         return false;
 
-    global->setReservedSlot(IMPORT_ENTRY_PROTO, ObjectValue(*proto));
+    global->initReservedSlot(IMPORT_ENTRY_PROTO, ObjectValue(*proto));
     return true;
 }
 
@@ -203,7 +203,7 @@ GlobalObject::initExportEntryProto(JSContext* cx, Handle<GlobalObject*> global)
     if (!DefinePropertiesAndFunctions(cx, proto, protoAccessors, nullptr))
         return false;
 
-    global->setReservedSlot(EXPORT_ENTRY_PROTO, ObjectValue(*proto));
+    global->initReservedSlot(EXPORT_ENTRY_PROTO, ObjectValue(*proto));
     return true;
 }
 
@@ -241,6 +241,71 @@ ExportEntryObject::create(ExclusiveContext* cx,
 }
 
 ///////////////////////////////////////////////////////////////////////////
+// RequestedModuleObject
+
+/* static */ const Class
+RequestedModuleObject::class_ = {
+    "RequestedModule",
+    JSCLASS_HAS_RESERVED_SLOTS(RequestedModuleObject::SlotCount) |
+    JSCLASS_IS_ANONYMOUS
+};
+
+DEFINE_GETTER_FUNCTIONS(RequestedModuleObject, moduleSpecifier, ModuleSpecifierSlot)
+DEFINE_GETTER_FUNCTIONS(RequestedModuleObject, lineNumber, LineNumberSlot)
+DEFINE_GETTER_FUNCTIONS(RequestedModuleObject, columnNumber, ColumnNumberSlot)
+
+DEFINE_ATOM_ACCESSOR_METHOD(RequestedModuleObject, moduleSpecifier)
+DEFINE_UINT32_ACCESSOR_METHOD(RequestedModuleObject, lineNumber)
+DEFINE_UINT32_ACCESSOR_METHOD(RequestedModuleObject, columnNumber)
+
+/* static */ bool
+RequestedModuleObject::isInstance(HandleValue value)
+{
+    return value.isObject() && value.toObject().is<RequestedModuleObject>();
+}
+
+/* static */ bool
+GlobalObject::initRequestedModuleProto(JSContext* cx, Handle<GlobalObject*> global)
+{
+    static const JSPropertySpec protoAccessors[] = {
+        JS_PSG("moduleSpecifier", RequestedModuleObject_moduleSpecifierGetter, 0),
+        JS_PSG("lineNumber", RequestedModuleObject_lineNumberGetter, 0),
+        JS_PSG("columnNumber", RequestedModuleObject_columnNumberGetter, 0),
+        JS_PS_END
+    };
+
+    RootedObject proto(cx, GlobalObject::createBlankPrototype<PlainObject>(cx, global));
+    if (!proto)
+        return false;
+
+    if (!DefinePropertiesAndFunctions(cx, proto, protoAccessors, nullptr))
+        return false;
+
+    global->initReservedSlot(REQUESTED_MODULE_PROTO, ObjectValue(*proto));
+    return true;
+}
+
+/* static */ RequestedModuleObject*
+RequestedModuleObject::create(JSContext* cx,
+                              HandleAtom moduleSpecifier,
+                              uint32_t lineNumber,
+                              uint32_t columnNumber)
+{
+    MOZ_ASSERT(lineNumber > 0);
+
+    RootedObject proto(cx, cx->global()->getRequestedModulePrototype());
+    RootedObject obj(cx, NewObjectWithGivenProto(cx, &class_, proto));
+    if (!obj)
+        return nullptr;
+
+    RootedRequestedModuleObject self(cx, &obj->as<RequestedModuleObject>());
+    self->initReservedSlot(ModuleSpecifierSlot, StringValue(moduleSpecifier));
+    self->initReservedSlot(LineNumberSlot, Int32Value(lineNumber));
+    self->initReservedSlot(ColumnNumberSlot, Int32Value(columnNumber));
+    return self;
+}
+
+///////////////////////////////////////////////////////////////////////////
 // IndirectBindingMap
 
 IndirectBindingMap::Binding::Binding(ModuleEnvironmentObject* environment, Shape* shape)
@@ -1074,7 +1139,8 @@ ModuleBuilder::ModuleBuilder(ExclusiveContext* cx, HandleModuleObject module,
   : cx_(cx),
     module_(cx, module),
     tokenStream_(tokenStream),
-    requestedModules_(cx, AtomVector(cx)),
+    requestedModuleSpecifiers_(cx, AtomSet(cx)),
+    requestedModules_(cx, RequestedModuleVector(cx)),
     importedBoundNames_(cx, AtomVector(cx)),
     importEntries_(cx, ImportEntryVector(cx)),
     exportEntries_(cx, ExportEntryVector(cx)),
@@ -1084,6 +1150,12 @@ ModuleBuilder::ModuleBuilder(ExclusiveContext* cx, HandleModuleObject module,
 {}
 
 bool
+ModuleBuilder::init()
+{
+    return requestedModuleSpecifiers_.init();
+}
+
+bool
 ModuleBuilder::buildTables()
 {
     for (const auto& e : exportEntries_) {
@@ -1130,24 +1202,23 @@ ModuleBuilder::buildTables()
 bool
 ModuleBuilder::initModule()
 {
-    RootedArrayObject requestedModules(cx_, createArray<JSAtom*>(requestedModules_));
+    RootedArrayObject requestedModules(cx_, createArray(requestedModules_));
     if (!requestedModules)
         return false;
 
-    RootedArrayObject importEntries(cx_, createArray<ImportEntryObject*>(importEntries_));
+    RootedArrayObject importEntries(cx_, createArray(importEntries_));
     if (!importEntries)
         return false;
 
-    RootedArrayObject localExportEntries(cx_, createArray<ExportEntryObject*>(localExportEntries_));
+    RootedArrayObject localExportEntries(cx_, createArray(localExportEntries_));
     if (!localExportEntries)
         return false;
 
-    RootedArrayObject indirectExportEntries(cx_);
-    indirectExportEntries = createArray<ExportEntryObject*>(indirectExportEntries_);
+    RootedArrayObject indirectExportEntries(cx_, createArray(indirectExportEntries_));
     if (!indirectExportEntries)
         return false;
 
-    RootedArrayObject starExportEntries(cx_, createArray<ExportEntryObject*>(starExportEntries_));
+    RootedArrayObject starExportEntries(cx_, createArray(starExportEntries_));
     if (!starExportEntries)
         return false;
 
@@ -1169,7 +1240,7 @@ ModuleBuilder::processImport(frontend::ParseNode* pn)
     MOZ_ASSERT(pn->pn_right->isKind(PNK_STRING));
 
     RootedAtom module(cx_, pn->pn_right->pn_atom);
-    if (!maybeAppendRequestedModule(module))
+    if (!maybeAppendRequestedModule(module, pn->pn_right))
         return false;
 
     for (ParseNode* spec = pn->pn_left->pn_head; spec; spec = spec->pn_next) {
@@ -1277,7 +1348,7 @@ ModuleBuilder::processExportFrom(frontend::ParseNode* pn)
     MOZ_ASSERT(pn->pn_right->isKind(PNK_STRING));
 
     RootedAtom module(cx_, pn->pn_right->pn_atom);
-    if (!maybeAppendRequestedModule(module))
+    if (!maybeAppendRequestedModule(module, pn->pn_right))
         return false;
 
     for (ParseNode* spec = pn->pn_left->pn_head; spec; spec = spec->pn_next) {
@@ -1346,29 +1417,26 @@ ModuleBuilder::appendExportFromEntry(HandleAtom exportName, HandleAtom moduleReq
 }
 
 bool
-ModuleBuilder::maybeAppendRequestedModule(HandleAtom module)
+ModuleBuilder::maybeAppendRequestedModule(HandleAtom specifier, ParseNode* node)
 {
-    for (auto m : requestedModules_) {
-        if (m == module)
-            return true;
+    if (requestedModuleSpecifiers_.has(specifier)) {
+        return true;
     }
-    return requestedModules_.append(module);
-}
-
-static Value
-MakeElementValue(JSString *string)
-{
-    return StringValue(string);
-}
-
-static Value
-MakeElementValue(JSObject *object)
-{
-    return ObjectValue(*object);
+    uint32_t line;
+    uint32_t column;
+    tokenStream_.srcCoords.lineNumAndColumnIndex(node->pn_pos.begin, &line, &column);
+    JSContext* cx = reinterpret_cast<JSContext*>(cx_);
+    RootedRequestedModuleObject req(cx, RequestedModuleObject::create(cx, specifier, line, column));
+    if (!req) {
+        return false;
+    }
+    return FreezeObject(cx, req) &&
+           requestedModules_.append(req) &&
+           requestedModuleSpecifiers_.put(specifier);
 }
 
 template <typename T>
-ArrayObject* ModuleBuilder::createArray(const GCVector<T>& vector)
+ArrayObject* ModuleBuilder::createArray(const JS::Rooted<GCVector<T>>& vector)
 {
     uint32_t length = vector.length();
     RootedArrayObject array(cx_, NewDenseFullyAllocatedArray(cx_, length));
@@ -1377,7 +1445,7 @@ ArrayObject* ModuleBuilder::createArray(const GCVector<T>& vector)
 
     array->setDenseInitializedLength(length);
     for (uint32_t i = 0; i < length; i++)
-        array->initDenseElement(i, MakeElementValue(vector[i]));
+        array->initDenseElement(i, ObjectValue(*vector[i]));
 
     return array;
 }
diff --git a/js/src/builtin/ModuleObject.h b/js/src/builtin/ModuleObject.h
index dc078e6b28..fde02c6938 100644
--- a/js/src/builtin/ModuleObject.h
+++ b/js/src/builtin/ModuleObject.h
@@ -100,6 +100,32 @@ class ExportEntryObject : public NativeObject
 typedef Rooted<ExportEntryObject*> RootedExportEntryObject;
 typedef Handle<ExportEntryObject*> HandleExportEntryObject;
 
+class RequestedModuleObject : public NativeObject
+{
+  public:
+    enum
+    {
+        ModuleSpecifierSlot = 0,
+        LineNumberSlot,
+        ColumnNumberSlot,
+        SlotCount
+    };
+
+    static const Class class_;
+    static JSObject* initClass(JSContext* cx, HandleObject obj);
+    static bool isInstance(HandleValue value);
+    static RequestedModuleObject* create(JSContext* cx,
+                                         HandleAtom moduleSpecifier,
+                                         uint32_t lineNumber,
+                                         uint32_t columnNumber);
+    JSAtom* moduleSpecifier() const;
+    uint32_t lineNumber() const;
+    uint32_t columnNumber() const;
+};
+
+typedef Rooted<RequestedModuleObject*> RootedRequestedModuleObject;
+typedef Handle<RequestedModuleObject*> HandleRequestedModuleObject;
+
 class IndirectBindingMap
 {
   public:
@@ -318,6 +344,8 @@ class MOZ_STACK_CLASS ModuleBuilder
     explicit ModuleBuilder(ExclusiveContext* cx, HandleModuleObject module,
                            const frontend::TokenStream& tokenStream);
 
+    bool init();
+
     bool processImport(frontend::ParseNode* pn);
     bool processExport(frontend::ParseNode* pn);
     bool processExportFrom(frontend::ParseNode* pn);
@@ -334,15 +362,20 @@ class MOZ_STACK_CLASS ModuleBuilder
 
   private:
     using AtomVector = GCVector<JSAtom*>;
-    using RootedAtomVector = JS::Rooted<AtomVector>;
     using ImportEntryVector = GCVector<ImportEntryObject*>;
+    using RequestedModuleVector = GCVector<RequestedModuleObject*>;
+    using AtomSet = JS::GCHashSet<JSAtom*>;
+    using RootedAtomVector = JS::Rooted<AtomVector>;
     using RootedImportEntryVector = JS::Rooted<ImportEntryVector>;
     using RootedExportEntryVector = JS::Rooted<ExportEntryVector>;
+    using RootedRequestedModuleVector = JS::Rooted<RequestedModuleVector>;
+    using RootedAtomSet = JS::Rooted<AtomSet>;
 
     ExclusiveContext* cx_;
     RootedModuleObject module_;
     const frontend::TokenStream& tokenStream_;
-    RootedAtomVector requestedModules_;
+    RootedAtomSet requestedModuleSpecifiers_;
+    RootedRequestedModuleVector requestedModules_;
     RootedAtomVector importedBoundNames_;
     RootedImportEntryVector importEntries_;
     RootedExportEntryVector exportEntries_;
@@ -357,10 +390,10 @@ class MOZ_STACK_CLASS ModuleBuilder
     bool appendExportFromEntry(HandleAtom exportName, HandleAtom moduleRequest,
                                HandleAtom importName, frontend::ParseNode* node);
 
-    bool maybeAppendRequestedModule(HandleAtom module);
+    bool maybeAppendRequestedModule(HandleAtom specifier, frontend::ParseNode* node);
 
     template <typename T>
-    ArrayObject* createArray(const GCVector<T>& vector);
+    ArrayObject* createArray(const JS::Rooted<GCVector<T>>& vector);
 };
 
 } // namespace js
diff --git a/js/src/builtin/ReflectParse.cpp b/js/src/builtin/ReflectParse.cpp
index 65bd16b270..ac69abab91 100644
--- a/js/src/builtin/ReflectParse.cpp
+++ b/js/src/builtin/ReflectParse.cpp
@@ -3741,6 +3741,9 @@ reflect_parse(JSContext* cx, uint32_t argc, Value* vp)
             return false;
 
         ModuleBuilder builder(cx, module, parser.tokenStream);
+        if (!builder.init())
+            return false;
+
         ModuleSharedContext modulesc(cx, module, &cx->global()->emptyGlobalScope(), builder);
         pn = parser.moduleBody(&modulesc);
         if (!pn)
diff --git a/js/src/frontend/BytecodeCompiler.cpp b/js/src/frontend/BytecodeCompiler.cpp
index 6dc837eb3b..2c01b5a9f2 100644
--- a/js/src/frontend/BytecodeCompiler.cpp
+++ b/js/src/frontend/BytecodeCompiler.cpp
@@ -405,6 +405,9 @@ BytecodeCompiler::compileModule()
     module->init(script);
 
     ModuleBuilder builder(cx, module, parser->tokenStream);
+    if (!builder.init())
+        return nullptr;
+
     ModuleSharedContext modulesc(cx, module, enclosingScope, builder);
     ParseNode* pn = parser->moduleBody(&modulesc);
     if (!pn)
diff --git a/js/src/gc/Policy.h b/js/src/gc/Policy.h
index 451dac1194..ba59336a52 100644
--- a/js/src/gc/Policy.h
+++ b/js/src/gc/Policy.h
@@ -46,6 +46,7 @@ class RegExpObject;
 class SavedFrame;
 class Scope;
 class EnvironmentObject;
+class RequestedModuleObject;
 class ScriptSourceObject;
 class Shape;
 class SharedArrayBufferObject;
@@ -84,6 +85,7 @@ class JitCode;
     D(js::PlainObject*) \
     D(js::PropertyName*) \
     D(js::RegExpObject*) \
+    D(js::RequestedModuleObject*) \
     D(js::SavedFrame*) \
     D(js::Scope*) \
     D(js::ScriptSourceObject*) \
diff --git a/js/src/jit-test/tests/modules/requested-modules.js b/js/src/jit-test/tests/modules/requested-modules.js
index ee572d12e3..acf58e5a6e 100644
--- a/js/src/jit-test/tests/modules/requested-modules.js
+++ b/js/src/jit-test/tests/modules/requested-modules.js
@@ -5,7 +5,7 @@ function testRequestedModules(source, expected) {
     var actual = module.requestedModules;
     assertEq(actual.length, expected.length);
     for (var i = 0; i < actual.length; i++) {
-        assertEq(actual[i], expected[i]);
+        assertEq(actual[i].moduleSpecifier, expected[i]);
     }
 }
 
diff --git a/js/src/jsapi.cpp b/js/src/jsapi.cpp
index dab4c25a43..4fb33464a6 100644
--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -4729,13 +4729,28 @@ JS::GetRequestedModules(JSContext* cx, JS::HandleObject moduleArg)
     return &moduleArg->as<ModuleObject>().requestedModules();
 }
 
-JS_PUBLIC_API(JSScript*)
-JS::GetModuleScript(JSContext* cx, JS::HandleObject moduleArg)
+JS_PUBLIC_API(JSString*)
+JS::GetRequestedModuleSpecifier(JSContext* cx, JS::HandleValue value)
 {
     AssertHeapIsIdle(cx);
     CHECK_REQUEST(cx);
-    assertSameCompartment(cx, moduleArg);
-    return moduleArg->as<ModuleObject>().script();
+    assertSameCompartment(cx, value);
+    JSObject* obj = &value.toObject();
+    return obj->as<RequestedModuleObject>().moduleSpecifier();
+}
+
+JS_PUBLIC_API(void)
+JS::GetRequestedModuleSourcePos(JSContext* cx, JS::HandleValue value,
+                                uint32_t* lineNumber, uint32_t* columnNumber)
+{
+    AssertHeapIsIdle(cx);
+    CHECK_REQUEST(cx);
+    assertSameCompartment(cx, value);
+    MOZ_ASSERT(lineNumber);
+    MOZ_ASSERT(columnNumber);
+    auto& requested = value.toObject().as<RequestedModuleObject>();
+    *lineNumber = requested.lineNumber();
+    *columnNumber = requested.columnNumber();
 }
 
 JS_PUBLIC_API(JSObject*)
diff --git a/js/src/jsapi.h b/js/src/jsapi.h
index f8203ee1fd..7d151fdb10 100644
--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -4386,18 +4386,27 @@ ModuleEvaluate(JSContext* cx, JS::HandleObject moduleRecord);
  * Get a list of the module specifiers used by a source text module
  * record to request importation of modules.
  *
- * The result is a JavaScript array of string values.  To extract the individual
- * values use only JS_GetArrayLength and JS_GetElement with indices 0 to
- * length - 1.
+ * The result is a JavaScript array of object values.  To extract the individual
+ * values use only JS_GetArrayLength and JS_GetElement with indices 0 to length
+ * - 1.
+ *
+ * The element values are objects with the following properties:
+ *  - moduleSpecifier: the module specifier string
+ *  - lineNumber: the line number of the import in the source text
+ *  - columnNumber: the column number of the import in the source text
+ *
+ * These property values can be extracted with GetRequestedModuleSpecifier() and
+ * GetRequestedModuleSourcePos()
  */
 extern JS_PUBLIC_API(JSObject*)
 GetRequestedModules(JSContext* cx, JS::HandleObject moduleRecord);
 
-/*
- * Get the script associated with a module.
- */
-extern JS_PUBLIC_API(JSScript*)
-GetModuleScript(JSContext* cx, JS::HandleObject moduleRecord);
+extern JS_PUBLIC_API(JSString*)
+GetRequestedModuleSpecifier(JSContext* cx, JS::HandleValue requestedModuleObject);
+
+extern JS_PUBLIC_API(void)
+GetRequestedModuleSourcePos(JSContext* cx, JS::HandleValue requestedModuleObject,
+                            uint32_t* lineNumber, uint32_t* columnNumber);
 
 } /* namespace JS */
 
diff --git a/js/src/vm/GlobalObject.h b/js/src/vm/GlobalObject.h
index 011f90aa16..865f5e5ece 100644
--- a/js/src/vm/GlobalObject.h
+++ b/js/src/vm/GlobalObject.h
@@ -112,6 +112,7 @@ class GlobalObject : public NativeObject
         MODULE_PROTO,
         IMPORT_ENTRY_PROTO,
         EXPORT_ENTRY_PROTO,
+        REQUESTED_MODULE_PROTO,
         REGEXP_STATICS,
         WARNED_ONCE_FLAGS,
         RUNTIME_CODEGEN_ENABLED,
@@ -524,6 +525,11 @@ class GlobalObject : public NativeObject
         return value.isUndefined() ? nullptr : &value.toObject();
     }
 
+    JSObject* maybeGetRequestedModulePrototype() {
+        Value value = getSlot(REQUESTED_MODULE_PROTO);
+        return value.isUndefined() ? nullptr : &value.toObject();
+    }
+
     JSObject* getModulePrototype() {
         JSObject* proto = maybeGetModulePrototype();
         MOZ_ASSERT(proto);
@@ -542,6 +548,12 @@ class GlobalObject : public NativeObject
         return proto;
     }
 
+    JSObject* getRequestedModulePrototype() {
+        JSObject* proto = maybeGetRequestedModulePrototype();
+        MOZ_ASSERT(proto);
+        return proto;
+    }
+
     static JSFunction*
     getOrCreateTypedArrayConstructor(JSContext* cx, Handle<GlobalObject*> global) {
         if (!ensureConstructor(cx, global, JSProto_TypedArray))
@@ -831,6 +843,7 @@ class GlobalObject : public NativeObject
     static bool initModuleProto(JSContext* cx, Handle<GlobalObject*> global);
     static bool initImportEntryProto(JSContext* cx, Handle<GlobalObject*> global);
     static bool initExportEntryProto(JSContext* cx, Handle<GlobalObject*> global);
+    static bool initRequestedModuleProto(JSContext* cx, Handle<GlobalObject*> global);
 
     // Implemented in builtin/TypedObject.cpp
     static bool initTypedObjectModule(JSContext* cx, Handle<GlobalObject*> global);