Enhance GN diagnostic tools

tools/gn/variables.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 "tools/gn/variables.h"
 
 namespace variables {
 
 // Built-in variables ----------------------------------------------------------
 
@@ skipping 760 matching lines @@
     "\n"
     "  If visibility is defined, only the targets with labels that match it\n"
     "  can depend on the current target. The empty list means no targets\n"
     "  can depend on the current target.\n"
     "\n"
     "  Tip: Often you will want the same visibility for all targets in a\n"
     "  BUILD file. In this case you can just put the definition at the top,\n"
     "  outside of any target, and the targets will inherit that scope and see\n"
     "  the definition.\n"
     "\n"
-    "Matching:\n"
+    "Patterns\n"
     "\n"
-    "  You can specify \"*\" but the inputs aren't general patterns. The\n"
-    "  following classes of patterns are supported:\n"
+    "  See \"gn help label_pattern\" for more details on what types of\n"
+    "  patterns are supported. If a toolchain is specified, only targets\n"
+    "  in that toolchain will be matched. If a toolchain is not specified on\n"
+    "  a pattern, targets in all toolchains will be matched.\n"
     "\n"
-    "   - Explicit (no wildcard):\n"
-    "       \"//foo/bar:baz\"\n"
-    "       \":baz\"\n"
-    "   - Wildcard target names:\n"
-    "       \"//foo/bar:*\" (any target in the //foo/bar/BUILD.gn file)\n"
-    "       \":*\"  (any target in the current build file)\n"
-    "   - Wildcard directory names (\"*\" is only supported at the end)\n"
-    "       \"*\"  (any target anywhere)\n"
-    "       \"//foo/bar/*\"  (any target in any subdir of //foo/bar)\n"
-    "       \"./*\"  (any target in the current build file or sub dirs)\n"
-    "\n"
-    "  The toolchain (normally an implicit part of a label) is ignored when\n"
-    "  checking visibility.\n"
-    "\n"
-    "Examples:\n"
+    "Examples\n"
     "\n"
     "  Only targets in the current buildfile (\"private\", the default):\n"
     "    visibility = \":*\"\n"
     "\n"
     "  No targets (used for targets that should be leaf nodes):\n"
     "    visibility = []\n"
     "\n"
     "  Any target (\"public\"):\n"
     "    visibility = \"*\"\n"
     "\n"
@@ skipping 78 matching lines @@
     INSERT_VARIABLE(Script)
     INSERT_VARIABLE(Sources)
     INSERT_VARIABLE(Visibility)
   }
   return info_map;
 }
 
 #undef INSERT_VARIABLE
 
 }  // namespace variables