tools/clang/blink_gc_plugin/BadPatternFinder.cpp

// Copyright 2017 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 "BadPatternFinder.h"
#include "DiagnosticsReporter.h"

#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"

using namespace clang::ast_matchers;

namespace {

TypeMatcher GarbageCollectedType() {
  auto has_gc_base = hasCanonicalType(hasDeclaration(
      cxxRecordDecl(isDerivedFrom(hasAnyName("::blink::GarbageCollected",
                                             "::blink::GarbageCollectedMixin")))
          .bind("gctype")));
  return anyOf(has_gc_base,
               hasCanonicalType(arrayType(hasElementType(has_gc_base))));
}

class UniquePtrGarbageCollectedMatcher : public MatchFinder::MatchCallback {
 public:
  explicit UniquePtrGarbageCollectedMatcher(DiagnosticsReporter& diagnostics)
      : diagnostics_(diagnostics) {}

  void Register(MatchFinder& match_finder) {
    // Matches any application of make_unique where the template argument is
    // known to refer to a garbage-collected type.
    auto make_unique_matcher =
        callExpr(
            callee(functionDecl(
                       hasAnyName("::std::make_unique", "::base::WrapUnique"),
                       hasTemplateArgument(
                           0, refersToType(GarbageCollectedType())))
                       .bind("badfunc")))
            .bind("bad");
    match_finder.addDynamicMatcher(make_unique_matcher, this);
  }

  void run(const MatchFinder::MatchResult& result) {
    auto* bad_use = result.Nodes.getNodeAs<clang::Expr>("bad");
    auto* bad_function = result.Nodes.getNodeAs<clang::FunctionDecl>("badfunc");
    auto* gc_type = result.Nodes.getNodeAs<clang::CXXRecordDecl>("gctype");
    diagnostics_.UniquePtrUsedWithGC(bad_use, bad_function, gc_type);
  }

 private:
  DiagnosticsReporter& diagnostics_;
};

class OptionalGarbageCollectedMatcher : public MatchFinder::MatchCallback {
 public:
  explicit OptionalGarbageCollectedMatcher(DiagnosticsReporter& diagnostics)
      : diagnostics_(diagnostics) {}

  void Register(MatchFinder& match_finder) {
    // Matches any application of make_unique where the template argument is
    // known to refer to a garbage-collected type.
    auto optional_construction =
        cxxConstructExpr(hasDeclaration(cxxConstructorDecl(ofClass(
                             classTemplateSpecializationDecl(
                                 hasName("::base::Optional"),
                                 hasTemplateArgument(
                                     0, refersToType(GarbageCollectedType())))
                                 .bind("optional")))))
            .bind("bad");
    match_finder.addDynamicMatcher(optional_construction, this);
  }

  void run(const MatchFinder::MatchResult& result) {
    auto* bad_use = result.Nodes.getNodeAs<clang::Expr>("bad");
    auto* optional = result.Nodes.getNodeAs<clang::CXXRecordDecl>("optional");
    auto* gc_type = result.Nodes.getNodeAs<clang::CXXRecordDecl>("gctype");
    diagnostics_.OptionalUsedWithGC(bad_use, optional, gc_type);
  }

 private:
  DiagnosticsReporter& diagnostics_;
};

}  // namespace

void FindBadPatterns(clang::ASTContext& ast_context,
                     DiagnosticsReporter& diagnostics) {
  MatchFinder match_finder;

  UniquePtrGarbageCollectedMatcher unique_ptr_gc(diagnostics);
  unique_ptr_gc.Register(match_finder);

  OptionalGarbageCollectedMatcher optional_gc(diagnostics);
  optional_gc.Register(match_finder);

  match_finder.matchAST(ast_context);
}