rewrite_to_chrome_style: skip nodes in synthesized functions.

Trickily enough, there were two matchers triggering this rewrite:
- the reference to the field being initialized in the synthesized copy
  constructor
- the reference to the field being copied in the synthesized copy
  constructor

BUG=581871

Review URL: https://codereview.chromium.org/1639133004

Cr-Commit-Position: refs/heads/master@{#372246}

tools/clang/rewrite_to_chrome_style/RewriteToChromeStyle.cpp

@@ -53,6 +53,12 @@ AST_MATCHER(clang::FunctionDecl, isOverloadedOperator) {
   return Node.isOverloadedOperator();
 }
 
+// This is available in newer clang revisions... but alas, Chrome has not rolled
+// that far yet.
+AST_MATCHER(clang::FunctionDecl, isDefaulted) {
+  return Node.isDefaulted();
+}
+
 const char kBlinkFieldPrefix[] = "m_";
 const char kBlinkStaticMemberPrefix[] = "s_";
 
@@ -230,6 +236,7 @@ struct TargetNodeTraits<clang::CXXCtorInitializer> {
   static const char kName[];
   static clang::CharSourceRange GetRange(
       const clang::CXXCtorInitializer& init) {
+    assert(init.isWritten());
     return clang::CharSourceRange::getTokenRange(init.getSourceLocation());
   }
 };
@@ -415,7 +422,16 @@ int main(int argc, const char* argv[]) {
   //     ...
   //   }
   // matches |x| in if (x).
-  auto member_matcher = id("expr", memberExpr(member(field_decl_matcher)));
+  auto member_matcher = id(
+      "expr",
+      memberExpr(
+          member(field_decl_matcher),
+          // Needed to avoid matching member references in functions (which will
+          // be an ancestor of the member reference) synthesized by the
+          // compiler, such as a synthesized copy constructor.
+          // This skips explicitly defaulted functions as well, but that's OK:
+          // there's nothing interesting to rewrite in those either.
+          unless(hasAncestor(functionDecl(isDefaulted())))));
   auto decl_ref_matcher = id("expr", declRefExpr(to(var_decl_matcher)));
 
   MemberRewriter member_rewriter(&replacements);
@@ -531,7 +547,8 @@ int main(int argc, const char* argv[]) {
   // matches each initializer in the constructor for S.
   auto constructor_initializer_matcher =
       cxxConstructorDecl(forEachConstructorInitializer(
-          id("initializer", cxxCtorInitializer(forField(field_decl_matcher)))));
+          id("initializer",
+             cxxCtorInitializer(forField(field_decl_matcher), isWritten()))));
 
   ConstructorInitializerRewriter constructor_initializer_rewriter(
       &replacements);

tools/clang/rewrite_to_chrome_style/tests/fields-expected.cc

@@ -4,6 +4,9 @@
 
 namespace blink {
 
+// Note: do not add any copy or move constructors to this class: doing so will
+// break test coverage that we don't clobber the class name by trying to emit
+// replacements for synthesized functions.
 class C {
  public:
   // Make sure initializers are updated to use the new names.
@@ -50,4 +53,8 @@ union U {
 void F() {
   // Test that references to a static field are correctly rewritten.
   blink::C::instance_count_++;
+  // Force instantiation of a copy constructor for blink::C to make sure field
+  // initializers for synthesized functions don't cause weird rewrites.
+  blink::C c;
+  blink::C c2 = c;
 }

tools/clang/rewrite_to_chrome_style/tests/fields-original.cc

@@ -4,6 +4,9 @@
 
 namespace blink {
 
+// Note: do not add any copy or move constructors to this class: doing so will
+// break test coverage that we don't clobber the class name by trying to emit
+// replacements for synthesized functions.
 class C {
  public:
   // Make sure initializers are updated to use the new names.
@@ -50,4 +53,8 @@ union U {
 void F() {
   // Test that references to a static field are correctly rewritten.
   blink::C::instanceCount++;
+  // Force instantiation of a copy constructor for blink::C to make sure field
+  // initializers for synthesized functions don't cause weird rewrites.
+  blink::C c;
+  blink::C c2 = c;
 }