GN: Make file/dir resolving return errors.

tools/gn/function_exec_script.cc

 // Copyright (c) 2013 The Chromium 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 "base/command_line.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
@@ skipping 115 matching lines @@
   }
 
   const Settings* settings = scope->settings();
   const BuildSettings* build_settings = settings->build_settings();
   const SourceDir& cur_dir = scope->GetSourceDir();
 
   if (!CheckExecScriptPermissions(build_settings, function, err))
     return Value();
 
   // Find the python script to run.
-  if (!args[0].VerifyTypeIs(Value::STRING, err))
+  SourceFile script_source =
+      cur_dir.ResolveRelativeFile(args[0], err,
+          scope->settings()->build_settings()->root_path_utf8());
+  if (err->has_error())
     return Value();
-  SourceFile script_source =
-      cur_dir.ResolveRelativeFile(args[0].string_value(),
-          scope->settings()->build_settings()->root_path_utf8());
   base::FilePath script_path = build_settings->GetFullPath(script_source);
   if (!build_settings->secondary_source_path().empty() &&
       !base::PathExists(script_path)) {
     // Fall back to secondary source root when the file doesn't exist.
     script_path = build_settings->GetFullPathSecondary(script_source);
   }
 
   ScopedTrace trace(TraceItem::TRACE_SCRIPT_EXECUTE, script_source.value());
   trace.SetToolchain(settings->toolchain_label());
 
   // Add all dependencies of this script, including the script itself, to the
   // build deps.
   g_scheduler->AddGenDependency(script_path);
   if (args.size() == 4) {
     const Value& deps_value = args[3];
     if (!deps_value.VerifyTypeIs(Value::LIST, err))
       return Value();
 
     for (const auto& dep : deps_value.list_value()) {
       if (!dep.VerifyTypeIs(Value::STRING, err))
         return Value();
       g_scheduler->AddGenDependency(
           build_settings->GetFullPath(cur_dir.ResolveRelativeFile(
-              dep.string_value(),
+              dep, err,
               scope->settings()->build_settings()->root_path_utf8())));
+      if (err->has_error())
+        return Value();
     }
   }
 
   // Make the command line.
   const base::FilePath& python_path = build_settings->python_path();
   base::CommandLine cmdline(python_path);
   cmdline.AppendArgPath(script_path);
 
   if (args.size() >= 2) {
     // Optional command-line arguments to the script.
@@ skipping 64 matching lines @@
                msg);
     return Value();
   }
 
   // Default to None value for the input conversion if unspecified.
   return ConvertInputToValue(scope->settings(), output, function,
                              args.size() >= 3 ? args[2] : Value(), err);
 }
 
 }  // namespace functions