GN: Make file/dir resolving return errors.

tools/gn/label_pattern.cc

 // Copyright 2014 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 "tools/gn/label_pattern.h"
 
 #include "base/strings/string_util.h"
 #include "tools/gn/err.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/value.h"
@@ skipping 165 matching lines @@
   // Resolve the part of the path that's not the wildcard.
   if (!path.empty()) {
     // The non-wildcard stuff better not have a wildcard.
     if (path.find('*') != base::StringPiece::npos) {
       *err = Err(value, "Label patterns only support wildcard suffixes.",
           "The pattern contained a '*' that wasn't at the end.");
       return LabelPattern();
     }
 
     // Resolve the non-wildcard stuff.
-    dir = current_dir.ResolveRelativeDir(path);
-    if (dir.is_null()) {
-      *err = Err(value, "Label pattern didn't resolve to a dir.",
-          "The directory name \"" + path.as_string() + "\" didn't\n"
-          "resolve to a directory.");
+    dir = current_dir.ResolveRelativeDir(value, path, err);
+    if (err->has_error())
       return LabelPattern();
-    }
   }
 
   // Resolve the name. At this point, we're doing wildcard matches so the
   // name should either be empty ("foo/*") or a wildcard ("foo:*");
   if (colon != std::string::npos && name != "*") {
     *err = Err(value, "Invalid label pattern.",
         "You seem to be using the wildcard more generally that is supported.\n"
         "Did you mean \"foo:*\" to match everything in the file, or\n"
         "\"./*\" to recursively match everything in the currend subtree.");
     return LabelPattern();
@@ skipping 58 matching lines @@
       break;
   }
 
   if (!toolchain_.is_null()) {
     result.push_back('(');
     result.append(toolchain_.GetUserVisibleName(false));
     result.push_back(')');
   }
   return result;
 }