TempRefPtrChecker.cpp

Enable keyboard shortcuts

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "TempRefPtrChecker.h"

#include "CustomMatchers.h"

constexpr const char *kCallExpr = "call-expr";

constexpr const char *kOperatorCallExpr = "operator-call";

void TempRefPtrChecker::registerMatchers(MatchFinder *AstMatcher) {

  AstMatcher->addMatcher(

      cxxOperatorCallExpr(

          hasOverloadedOperatorName("->"),

          hasAnyArgument(implicitCastExpr(

              hasSourceExpression(materializeTemporaryExpr(anyOf(

                  hasDescendant(callExpr().bind(kCallExpr)), anything()))))),

          callee(hasDeclContext(classTemplateSpecializationDecl(

              isSmartPtrToRefCountedDecl(),

              // ignore any calls on temporary RefPtr<MozPromise<T>>,

              // since these typically need to be locally ref-counted,

              // e.g. in Then chains where the promise might be resolved

              // concurrently

              unless(hasTemplateArgument(

                  0, refersToType(hasDeclaration(

                         cxxRecordDecl(hasName("mozilla::MozPromise"))))))))))

          .bind(kOperatorCallExpr),

      this);

void TempRefPtrChecker::check(const MatchFinder::MatchResult &Result) {

  const auto *OCE =

      Result.Nodes.getNodeAs<CXXOperatorCallExpr>(kOperatorCallExpr);

  const auto *refPtrDecl =

      dyn_cast<const CXXRecordDecl>(OCE->getCalleeDecl()->getDeclContext());

  diag(OCE->getOperatorLoc(),

       "performance issue: temporary %0 is only dereferenced here once which "

       "involves short-lived AddRef/Release calls")

      << refPtrDecl;

  const auto *InnerCE = Result.Nodes.getNodeAs<CallExpr>(kCallExpr);

  if (InnerCE) {

    const auto functionName =

        InnerCE->getCalleeDecl()->getAsFunction()->getQualifiedNameAsString();

    if (functionName != "mozilla::MakeRefPtr") {

      diag(

          OCE->getOperatorLoc(),

          "consider changing function %0 to return a raw reference instead (be "

          "sure that the pointee is held alive by someone else though!)",

          DiagnosticIDs::Note)

          << functionName;