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-rw-r--r--build/clang-plugin/alpha/TempRefPtrChecker.cpp57
1 files changed, 57 insertions, 0 deletions
diff --git a/build/clang-plugin/alpha/TempRefPtrChecker.cpp b/build/clang-plugin/alpha/TempRefPtrChecker.cpp
new file mode 100644
index 0000000000..0a4d078368
--- /dev/null
+++ b/build/clang-plugin/alpha/TempRefPtrChecker.cpp
@@ -0,0 +1,57 @@
+/* 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;
+ }
+ }
+}