clang-plugin: Enable RecursiveASTVisitor approach by default.

tools/clang/plugins/FindBadConstructsConsumer.cpp

 // Copyright (c) 2012 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 "FindBadConstructsConsumer.h"
 
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/AST/Attr.h"
 #include "clang/Lex/Lexer.h"
 #include "llvm/Support/raw_ostream.h"
@@ skipping 261 matching lines @@
 
   int ctor_score = dtor_score;
   // You should be able to have 9 ints before we warn you.
   ctor_score += trivial_member;
 
   if (ctor_score >= 10) {
     if (!record->hasUserDeclaredConstructor()) {
       emitWarning(record_location,
                   "Complex class/struct needs an explicit out-of-line "
                   "constructor.");
-    } else {
+    } else if (options_.check_implicit_copy_ctors) {

[dcheng, 2016/02/16 23:03:50]

Since this flag is about implicit constructors, and this else branch seems to
handle lots of things, would it make sense to check this flag on line 293
instead?

Also, do the plugin tests need to be updated? I know that we hardcode
with-ast-visitor for the tests right now: should we update this flag?

[vmpstr, 2016/02/16 23:13:27]

The move ctor branch would have the same issues as the copy ctor branch (I
couldn't think of a better flag name though)

The branch on 319 also generated additional errors with the RAV approach. Let me
dig in a bit more to see what those were. 
Oops, done.

       // Iterate across all the constructors in this file and yell if we
       // find one that tries to be inline.
       for (CXXRecordDecl::ctor_iterator it = record->ctor_begin();
            it != record->ctor_end();
            ++it) {
         // The current check is buggy. An implicit copy constructor does not
         // have an inline body, so this check never fires for classes with a
         // user-declared out-of-line constructor.
         if (it->hasInlineBody()) {
           if (it->isCopyConstructor() &&
@@ skipping 573 matching lines @@
     // one of those, it means there is at least one member after a factory.
     if (weak_ptr_factory_location.isValid() &&
         !param_is_weak_ptr_factory_to_self) {
       diagnostic().Report(weak_ptr_factory_location,
                           diag_weak_ptr_factory_order_);
     }
   }
 }
 
 }  // namespace chrome_checker