Add more phony rules to GN build

tools/gn/ninja_build_writer.cc

Index: tools/gn/ninja_build_writer.cc
diff --git a/tools/gn/ninja_build_writer.cc b/tools/gn/ninja_build_writer.cc
index 11b36e6b591e74a85753f2998aad2dcfe003dc36..c0fc7fcfedfd9667c26de0984cf2fca47c7f92d1 100644
--- a/tools/gn/ninja_build_writer.cc
+++ b/tools/gn/ninja_build_writer.cc
@@ -11,6 +11,7 @@
 #include "base/file_util.h"
 #include "base/path_service.h"
 #include "base/process/process_handle.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "tools/gn/build_settings.h"
@@ -179,30 +180,87 @@ void NinjaBuildWriter::WritePhonyAndAllRules() {
 
   // Write phony rules for all uniquely-named targets in the default toolchain.
   // Don't do other toolchains or we'll get naming conflicts, and if the name
-  // isn't unique, also skip it.
+  // isn't unique, also skip it. The exception is for the toplevel targets
+  // which we also find.
   std::map<std::string, int> small_name_count;
-  for (size_t i = 0; i < default_toolchain_targets_.size(); i++)
-    small_name_count[default_toolchain_targets_[i]->label().name()]++;
-
+  std::vector<const Target*> toplevel_targets;
   for (size_t i = 0; i < default_toolchain_targets_.size(); i++) {
     const Target* target = default_toolchain_targets_[i];
+    const Label& label = target->label();
+    small_name_count[label.name()]++;
+
+    // Look for targets with a name of the form
+    //   dir = "//foo/", name = "foo"
+    // i.e. where the target name matches the top level directory. We will
+    // always write phony rules for these even if there is another target with
+    // the same short name.
+    const std::string& dir_string = label.dir().value();
+    if (dir_string.size() == label.name().size() + 3 &&  // Size matches.
+        dir_string[0] == '/' && dir_string[1] == '/' &&  // "//" at beginning.
+        dir_string[dir_string.size() - 1] == '/' &&  // "/" at end.
+        dir_string.compare(2, label.name().size(), label.name()) == 0)
+      toplevel_targets.push_back(target);
+  }
 
+  for (size_t i = 0; i < default_toolchain_targets_.size(); i++) {
+    const Target* target = default_toolchain_targets_[i];
+    const Label& label = target->label();
     OutputFile target_file = helper_.GetTargetOutputFile(target);
-    if (target_file.value() != target->label().name() &&
-        small_name_count[default_toolchain_targets_[i]->label().name()] == 1) {
-      out_ << "build " << target->label().name() << ": phony ";
-      path_output_.WriteFile(out_, target_file);
-      out_ << std::endl;
+
+    // Write the long name "foo/bar:baz" for the target "//foo/bar:baz".
+    std::string long_name = label.GetUserVisibleName(false);
+    base::TrimString(long_name, "/", &long_name);
+    WritePhonyRule(target, target_file, long_name);
+
+    // Write the directory name with no target name if they match
+    // (e.g. "//foo/bar:bar" -> "foo/bar").
+    if (FindLastDirComponent(label.dir()) == label.name()) {
+      std::string medium_name =  DirectoryWithNoLastSlash(label.dir());
+      base::TrimString(medium_name, "/", &medium_name);
+      // That may have generated a name the same as the short name of the
+      // target which we already wrote.
+      if (medium_name != label.name())
+        WritePhonyRule(target, target_file, medium_name);
     }
 
+    // Write short names for ones which are unique.
+    if (small_name_count[label.name()] == 1)
+      WritePhonyRule(target, target_file, label.name());
+
     if (!all_rules.empty())
       all_rules.append(" $\n    ");
     all_rules.append(target_file.value());
   }
 
+  // Pick up phony rules for the toplevel targets with non-unique names (which
+  // would have been skipped in the above loop).
+  for (size_t i = 0; i < toplevel_targets.size(); i++) {
+    if (small_name_count[toplevel_targets[i]->label().name()] > 1) {
+      const Target* target = toplevel_targets[i];
+      WritePhonyRule(target, helper_.GetTargetOutputFile(target),
+                     target->label().name());
+    }
+  }
+
   if (!all_rules.empty()) {
     out_ << "\nbuild all: phony " << all_rules << std::endl;
     out_ << "default all" << std::endl;
   }
 }
 
+void NinjaBuildWriter::WritePhonyRule(const Target* target,
+                                      const OutputFile& target_file,
+                                      const std::string& phony_name) {
+  if (target_file.value() == phony_name)
+    return;  // No need for a phony rule.
+
+  EscapeOptions ninja_escape;
+  ninja_escape.mode = ESCAPE_NINJA;
+
+  // Escape for special chars Ninja will handle.
+  std::string escaped = EscapeString(phony_name, ninja_escape, NULL);
+
+  out_ << "build " << escaped << ": phony ";
+  path_output_.WriteFile(out_, target_file);
+  out_ << std::endl;
+}