Add a new dotfile command line argument to GN

This allows one to specify the .gn file manually when also overriding the
--root source path.

This removes the --secondary command line argument. There's no use case to
specify this on the command line rather than in the .gn file.

Improves some error reporting if the root path isn't found.

Fixes a crash in scope tear-down. When crating a closure or doing a scope merge, the template pointers would be copied rather than the template objects, but the scope expects to own the pointers. This would result in a double-delete. The solution is to create a new copy of the template in the Scope::NonRecursiveMergeTo

BUG=
R=noelallen@chromium.org

Review URL: https://codereview.chromium.org/218403014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@262040 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 71 insertions, 21 deletions

diff --git a/tools/gn/setup.cc b/tools/gn/setup.cc
index 728a8eb..e2e17fa 100644
--- a/tools/gn/setup.cc
+++ b/tools/gn/setup.cc
@@ -44,12 +44,23 @@ extern const char kDotfile_Help[] =
     "  same as a buildfile, but with very limited build setup-specific\n"
     "  meaning.\n"
     "\n"
+    "  If you specify --root, by default GN will look for the file .gn in\n"
+    "  that directory. If you want to specify a different file, you can\n"
+    "  additionally pass --dotfile:\n"
+    "\n"
+    "    gn gen out/Debug --root=/home/build --dotfile=/home/my_gn_file.gn\n"
+    "\n"
     "Variables\n"
     "\n"
     "  buildconfig [required]\n"
     "      Label of the build config file. This file will be used to setup\n"
     "      the build file execution environment for each toolchain.\n"
     "\n"
+    "  root [optional]\n"
+    "      Label of the root build target. The GN build will start by loading\n"
+    "      the build file containing this target name. This defaults to\n"
+    "      \"//:\" which will cause the file //BUILD.gn to be loaded.\n"
+    "\n"
     "  secondary_source [optional]\n"
     "      Label of an alternate directory tree to find input files. When\n"
     "      searching for a BUILD.gn file (or the build config file discussed\n"
@@ -66,6 +77,8 @@ extern const char kDotfile_Help[] =
     "\n"
     "  buildconfig = \"//build/config/BUILDCONFIG.gn\"\n"
     "\n"
+    "  root = \"//:root\"\n"
+    "\n"
     "  secondary_source = \"//build/config/temporary_buildfiles/\"\n";
 
 namespace {
@@ -79,13 +92,14 @@ const char kSwitchArgs[] = "args";
 // Set root dir.
 const char kSwitchRoot[] = "root";
 
+// Set dotfile name.
+const char kSwitchDotfile[] = "dotfile";
+
 // Enable timing.
 const char kTimeSwitch[] = "time";
 
 const char kTracelogSwitch[] = "tracelog";
 
-const char kSecondarySource[] = "secondary";
-
 const base::FilePath::CharType kGnFile[] = FILE_PATH_LITERAL(".gn");
 
 base::FilePath FindDotFile(const base::FilePath& current_dir) {
@@ -122,6 +136,7 @@ CommonSetup::CommonSetup()
     : build_settings_(),
       loader_(new LoaderImpl(&build_settings_)),
       builder_(new Builder(loader_.get())),
+      root_build_file_("//BUILD.gn"),
       check_for_bad_items_(true),
       check_for_unused_overrides_(true) {
   loader_->set_complete_callback(base::Bind(&DecrementWorkCount));
@@ -131,6 +146,7 @@ CommonSetup::CommonSetup(const CommonSetup& other)
     : build_settings_(other.build_settings_),
       loader_(new LoaderImpl(&build_settings_)),
       builder_(new Builder(loader_.get())),
+      root_build_file_(other.root_build_file_),
       check_for_bad_items_(other.check_for_bad_items_),
       check_for_unused_overrides_(other.check_for_unused_overrides_) {
   loader_->set_complete_callback(base::Bind(&DecrementWorkCount));
@@ -141,7 +157,7 @@ CommonSetup::~CommonSetup() {
 
 void CommonSetup::RunPreMessageLoop() {
   // Load the root build file.
-  loader_->Load(SourceFile("//BUILD.gn"), Label());
+  loader_->Load(root_build_file_, Label());
 
   // Will be decremented with the loader is drained.
   g_scheduler->IncrementWorkCount();
@@ -271,8 +287,31 @@ bool Setup::FillSourceDir(const CommandLine& cmdline) {
   base::FilePath relative_root_path = cmdline.GetSwitchValuePath(kSwitchRoot);
   if (!relative_root_path.empty()) {
     root_path = base::MakeAbsoluteFilePath(relative_root_path);
-    dotfile_name_ = root_path.Append(kGnFile);
+    if (root_path.empty()) {
+      Err(Location(), "Root source path not found.",
+          "The path \"" + FilePathToUTF8(relative_root_path) +
+          "\" doesn't exist.").PrintToStdout();
+      return false;
+    }
+
+    // When --root is specified, an alternate --dotfile can also be set.
+    // --dotfile should be a real file path and not a "//foo" source-relative
+    // path.
+    base::FilePath dot_file_path = cmdline.GetSwitchValuePath(kSwitchDotfile);
+    if (dot_file_path.empty()) {
+      dotfile_name_ = root_path.Append(kGnFile);
+    } else {
+      dotfile_name_ = base::MakeAbsoluteFilePath(dot_file_path);
+      if (dotfile_name_.empty()) {
+        Err(Location(), "Could not load dotfile.",
+            "The file \"" + FilePathToUTF8(dot_file_path) +
+            "\" cound't be loaded.").PrintToStdout();
+        return false;
+      }
+    }
   } else {
+    // In the default case, look for a dotfile and that also tells us where the
+    // source root is.
     base::FilePath cur_dir;
     base::GetCurrentDirectory(&cur_dir);
     dotfile_name_ = FindDotFile(cur_dir);
@@ -369,24 +408,35 @@ bool Setup::RunConfigFile() {
 bool Setup::FillOtherConfig(const CommandLine& cmdline) {
   Err err;
 
-  // Secondary source path.
-  SourceDir secondary_source;
-  if (cmdline.HasSwitch(kSecondarySource)) {
-    // Prefer the command line over the config file.
-    secondary_source =
-        SourceDir(cmdline.GetSwitchValueASCII(kSecondarySource));
-  } else {
-    // Read from the config file if present.
-    const Value* secondary_value =
-        dotfile_scope_.GetValue("secondary_source", true);
-    if (secondary_value) {
-      if (!secondary_value->VerifyTypeIs(Value::STRING, &err)) {
-        err.PrintToStdout();
-        return false;
-      }
-      build_settings_.SetSecondarySourcePath(
-          SourceDir(secondary_value->string_value()));
+  // Secondary source path, read from the config file if present.
+  // Read from the config file if present.
+  const Value* secondary_value =
+      dotfile_scope_.GetValue("secondary_source", true);
+  if (secondary_value) {
+    if (!secondary_value->VerifyTypeIs(Value::STRING, &err)) {
+      err.PrintToStdout();
+      return false;
     }
+    build_settings_.SetSecondarySourcePath(
+        SourceDir(secondary_value->string_value()));
+  }
+
+  // Root build file.
+  const Value* root_value = dotfile_scope_.GetValue("root", true);
+  if (root_value) {
+    if (!root_value->VerifyTypeIs(Value::STRING, &err)) {
+      err.PrintToStdout();
+      return false;
+    }
+
+    Label root_target_label =
+        Label::Resolve(SourceDir("//"), Label(), *root_value, &err);
+    if (err.has_error()) {
+      err.PrintToStdout();
+      return false;
+    }
+
+    root_build_file_ = Loader::BuildFileForLabel(root_target_label);
   }
 
   // Build config file.