gn format: Support # NOSORT to disable sorting of blocks

tools/gn/command_format.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 <stddef.h>
 
 #include <sstream>
 
 #include "base/command_line.h"
 #include "base/files/file_util.h"
@@ skipping 17 matching lines @@
 const char kSwitchStdin[] = "stdin";
 
 const char kFormat[] = "format";
 const char kFormat_HelpShort[] =
     "format: Format .gn file.";
 const char kFormat_Help[] =
     "gn format [--dump-tree] [--in-place] [--stdin] BUILD.gn\n"
     "\n"
     "  Formats .gn file to a standard format.\n"
     "\n"
+    "  The contents of some lists ('sources', 'deps', etc.) will be sorted to\n"
+    "  a canonical order. To suppress this, you can add a comment of the form\n"
+    "  \"# NOSORT\" immediately preceeding the assignment. e.g.\n"
+    "\n"
+    "  # NOSORT\n"
+    "  sources = [\n"
+    "    \"z.cc\",\n"
+    "    \"a.cc\",\n"
+    "  ]\n"
+    "\n"
     "Arguments\n"
     "  --dry-run\n"
     "      Does not change or output anything, but sets the process exit code\n"
     "      based on whether output would be different than what's on disk.\n"
     "      This is useful for presubmit/lint-type checks.\n"
     "      - Exit code 0: successful format, matches on disk.\n"
     "      - Exit code 1: general failure (parse error, etc.)\n"
     "      - Exit code 2: successful format, but differs from on disk.\n"
     "\n"
     "  --dump-tree\n"
@@ skipping 260 matching lines @@
     const base::StringPiece lhs = ident->value().value();
     if (lhs == "data" || lhs == "datadeps" || lhs == "data_deps" ||
         lhs == "deps" || lhs == "inputs" || lhs == "outputs" ||
         lhs == "public" || lhs == "public_deps" || lhs == "sources") {
       const_cast<ListNode*>(list)->set_prefer_multiline(true);
     }
   }
 }
 
 void Printer::SortIfSourcesOrDeps(const BinaryOpNode* binop) {
+  if (binop && binop->comments() && !binop->comments()->before().empty() &&
+      binop->comments()->before()[0].value().as_string() == "# NOSORT") {
+    // Allow disabling of sort for specific actions that might be
+    // order-sensitive.
+    return;
+  }
   const IdentifierNode* ident = binop->left()->AsIdentifier();
   const ListNode* list = binop->right()->AsList();
   if ((binop->op().value() == "=" || binop->op().value() == "+=" ||
        binop->op().value() == "-=") &&
       ident && list) {
     const base::StringPiece lhs = ident->value().value();
     if (lhs == "sources")
       const_cast<ListNode*>(list)->SortAsStringsList();
     else if (lhs == "deps" || lhs == "public_deps")
       const_cast<ListNode*>(list)->SortAsDepsList();
@@ skipping 724 matching lines @@
       }
     } else {
       printf("%s", output_string.c_str());
     }
   }
 
   return 0;
 }
 
 }  // namespace commands