Improve accuracy of detecting type trait fields.

tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp

 // Copyright 2015 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.
 //
 // Changes Blink-style names to Chrome-style names. Currently transforms:
 //   fields:
 //     int m_operationCount => int operation_count_
 //   variables (including parameters):
 //     int mySuperVariable => int my_super_variable
 //   constants:
@@ skipping 83 matching lines @@
   if (Node.getNumDecls() == 0)
     return false;
 
   for (clang::NamedDecl* decl : Node.decls()) {
     if (!InnerMatcher.matches(*decl, Finder, Builder))
       return false;
   }
   return true;
 }
 
-bool IsDeclContextInWTF(const clang::DeclContext* decl_context) {
-  auto* namespace_decl = clang::dyn_cast_or_null<clang::NamespaceDecl>(
-      decl_context->getEnclosingNamespaceContext());
-  if (!namespace_decl)
-    return false;
-  if (namespace_decl->getParent()->isTranslationUnit() &&
-      namespace_decl->getName() == "WTF")
-    return true;
-  return IsDeclContextInWTF(namespace_decl->getParent());
-}
-
 template <typename T>
 bool MatchAllOverriddenMethods(
     const clang::CXXMethodDecl& decl,
     T&& inner_matcher,
     clang::ast_matchers::internal::ASTMatchFinder* finder,
     clang::ast_matchers::internal::BoundNodesTreeBuilder* builder) {
   bool override_matches = false;
   bool override_not_matches = false;
 
   for (auto it = decl.begin_overridden_methods();
@@ skipping 321 matching lines @@
   // static class members match against VarDecls. Blink style dictates that
   // these should be prefixed with `s_`, so strip that off. Also check for `m_`
   // and strip that off too, for code that accidentally uses the wrong prefix.
   if (original_name.startswith(kBlinkStaticMemberPrefix))
     original_name = original_name.substr(strlen(kBlinkStaticMemberPrefix));
   else if (original_name.startswith(kBlinkFieldPrefix))
     original_name = original_name.substr(strlen(kBlinkFieldPrefix));
 
   bool is_const = IsProbablyConst(decl, context);
   if (is_const) {
-    // Struct consts in WTF do not become kFoo cuz stuff like type traits
-    // should stay as lowercase.
-    const clang::DeclContext* decl_context = decl.getDeclContext();
-    bool is_in_wtf = IsDeclContextInWTF(decl_context);
-    const clang::CXXRecordDecl* parent =
-        clang::dyn_cast_or_null<clang::CXXRecordDecl>(decl_context);
-    if (is_in_wtf && parent && parent->isStruct())
+    // Given
+    //   namespace WTF {
+    //     struct TypeTrait {
+    //       static const bool value = ...;
+    //     };
+    //   }
+    // matches |value|.
+    auto type_trait_matcher = varDecl(
+        hasName("value"),
+        hasStaticStorageDuration(),
+        hasType(isConstQualified()),
+        hasType(booleanType()),
+        hasAncestor(recordDecl(hasAncestor(namespaceDecl(
+            hasName("WTF"), hasParent(translationUnitDecl()))))));

[dcheng, 2016/08/24 21:42:17]

Since this is expressed as a matcher now, should we just move it into
field_decl_matcher?

[Łukasz Anforowicz, 2016/08/24 21:55:09]

Good point.  Done.  (although this has to go to |var_decl_matcher| - I think
static fields are varDecls, not fieldDecls (which I think only cover instance
fields?  I might be confused here...).

+
+    // Avoid renaming |value| -> |kValue| in WTF type traits.
+    if (!match(type_trait_matcher, decl, context).empty())
       return false;
 
     if (!GetNameForConstant(original_name.str(), name))
       return false;
   } else {
     name = CamelCaseToUnderscoreCase(original_name);
 
     // Non-const variables with static storage duration at namespace scope are
     // prefixed with `g_' to reduce the likelihood of a naming collision.
     const clang::DeclContext* decl_context = decl.getDeclContext();
@@ skipping 737 matching lines @@
   for (const auto& r : replacements) {
     std::string replacement_text = r.getReplacementText().str();
     std::replace(replacement_text.begin(), replacement_text.end(), '\n', '\0');
     llvm::outs() << "r:::" << r.getFilePath() << ":::" << r.getOffset()
                  << ":::" << r.getLength() << ":::" << replacement_text << "\n";
   }
   llvm::outs() << "==== END EDITS ====\n";
 
   return 0;
 }