tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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TempRefPtrChecker.cpp (2266B)

      1 /* This Source Code Form is subject to the terms of the Mozilla Public
      2 * License, v. 2.0. If a copy of the MPL was not distributed with this
      3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      4 
      5 #include "TempRefPtrChecker.h"
      6 #include "CustomMatchers.h"
      7 
      8 constexpr const char *kCallExpr = "call-expr";
      9 constexpr const char *kOperatorCallExpr = "operator-call";
     10 
     11 void TempRefPtrChecker::registerMatchers(MatchFinder *AstMatcher) {
     12  AstMatcher->addMatcher(
     13      cxxOperatorCallExpr(
     14          hasOverloadedOperatorName("->"),
     15          hasAnyArgument(implicitCastExpr(
     16              hasSourceExpression(materializeTemporaryExpr(anyOf(
     17                  hasDescendant(callExpr().bind(kCallExpr)), anything()))))),
     18          callee(hasDeclContext(classTemplateSpecializationDecl(
     19              isSmartPtrToRefCountedDecl(),
     20              // ignore any calls on temporary RefPtr<MozPromise<T>>,
     21              // since these typically need to be locally ref-counted,
     22              // e.g. in Then chains where the promise might be resolved
     23              // concurrently
     24              unless(hasTemplateArgument(
     25                  0, refersToType(hasDeclaration(
     26                         cxxRecordDecl(hasName("mozilla::MozPromise"))))))))))
     27          .bind(kOperatorCallExpr),
     28      this);
     29 }
     30 
     31 void TempRefPtrChecker::check(const MatchFinder::MatchResult &Result) {
     32  const auto *OCE =
     33      Result.Nodes.getNodeAs<CXXOperatorCallExpr>(kOperatorCallExpr);
     34 
     35  const auto *refPtrDecl =
     36      dyn_cast<const CXXRecordDecl>(OCE->getCalleeDecl()->getDeclContext());
     37 
     38  diag(OCE->getOperatorLoc(),
     39       "performance issue: temporary %0 is only dereferenced here once which "
     40       "involves short-lived AddRef/Release calls")
     41      << refPtrDecl;
     42 
     43  const auto *InnerCE = Result.Nodes.getNodeAs<CallExpr>(kCallExpr);
     44  if (InnerCE) {
     45    const auto functionName =
     46        InnerCE->getCalleeDecl()->getAsFunction()->getQualifiedNameAsString();
     47 
     48    if (functionName != "mozilla::MakeRefPtr") {
     49      diag(
     50          OCE->getOperatorLoc(),
     51          "consider changing function %0 to return a raw reference instead (be "
     52          "sure that the pointee is held alive by someone else though!)",
     53          DiagnosticIDs::Note)
     54          << functionName;
     55    }
     56  }
     57 }