[wasm] Differentiate unnamed and empty names

src/wasm/wasm-module.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/macro-assembler.h"
 #include "src/objects.h"
 #include "src/property-descriptor.h"
 #include "src/v8.h"
 
 #include "src/simulator.h"
@@ skipping 322 matching lines @@
       max_mem_pages(0),
       mem_export(false),
       mem_external(false),
       start_function_index(-1),
       origin(kWasmOrigin) {}
 
 static MaybeHandle<JSFunction> ReportFFIError(ErrorThrower& thrower,
                                               const char* error, uint32_t index,
                                               wasm::WasmName module_name,
                                               wasm::WasmName function_name) {
-  if (function_name.start()) {
+  if (!function_name.is_empty()) {
     thrower.Error("Import #%d module=\"%.*s\" function=\"%.*s\" error: %s",
                   index, module_name.length(), module_name.start(),
                   function_name.length(), function_name.start(), error);
   } else {
     thrower.Error("Import #%d module=\"%.*s\" error: %s", index,
                   module_name.length(), module_name.start(), error);
   }
   thrower.Error("Import ");
   return MaybeHandle<JSFunction>();
 }
@@ skipping 15 matching lines @@
   }
 
   Handle<Object> module = result.ToHandleChecked();
 
   if (!module->IsJSReceiver()) {
     return ReportFFIError(thrower, "module is not an object or function", index,
                           module_name, function_name);
   }
 
   Handle<Object> function;
-  if (function_name.start()) {
+  if (!function_name.is_empty()) {
     // Look up the function in the module.
     Handle<String> name = factory->InternalizeUtf8String(function_name);
     MaybeHandle<Object> result = Object::GetProperty(module, name);
     if (result.is_null()) {
       return ReportFFIError(thrower, "function not found", index, module_name,
                             function_name);
     }
     function = result.ToHandleChecked();
   } else {
     // No function specified. Use the "default export".
@@ skipping 426 matching lines @@
       wasm->GetInternalField(kWasmFunctionNamesArray), wasm->GetIsolate());
   if (func_names_arr_obj->IsUndefined())
     return func_names_arr_obj;  // Return undefined.
   return GetWasmFunctionNameFromTable(
       Handle<ByteArray>::cast(func_names_arr_obj), func_index);
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8