Use simplify operator< implementations in tools/

tools/gn/label.h

Index: tools/gn/label.h
diff --git a/tools/gn/label.h b/tools/gn/label.h
index 88336eafa6d2540132547388173a384d14d606c6..172cbbe511ad034ff06f5a173e6f32d27ebd331d 100644
--- a/tools/gn/label.h
+++ b/tools/gn/label.h
@@ -71,14 +71,12 @@ class Label {
     return !operator==(other);
   }
   bool operator<(const Label& other) const {
-    // TODO(brettw) could be optimized to avoid an extra full string check
-    // (one for operator==, one for <).
-    if (dir_ != other.dir_)
-      return dir_ < other.dir_;
-    if (name_ != other.name_)
-      return name_ < other.name_;
-    if (toolchain_dir_ != other.toolchain_dir_)
-      return toolchain_dir_ < other.toolchain_dir_;
+    if (int c = dir_.compare(other.dir_))

[brettw, 2015/11/20 21:44:31]

You didn't use tie here to avoid the double-checking?

[jsbell, 2015/11/20 22:04:27]

Correct. I assumed (based on the TODO) that there was some concern about
performance.

(Happy to redo it with tie, though!)

+      return c == -1;
+    if (int c = name_.compare(other.name_))
+      return c == -1;
+    if (int c = toolchain_dir_.compare(other.toolchain_dir_))

[brettw, 2015/11/20 22:17:57]

You can use value() on the dir names to get the string out (no copies).

+      return c == -1;
     return toolchain_name_ < other.toolchain_name_;
   }