1 files changed, 81 insertions, 0 deletions
diff --git a/clang/lib/StaticAnalyzer/Checkers/CXXSelfAssignmentChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CXXSelfAssignmentChecker.cpp
new file mode 100644
index 000000000000..01f5b9c889e3
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/CXXSelfAssignmentChecker.cpp
@@ -0,0 +1,81 @@
+//=== CXXSelfAssignmentChecker.cpp -----------------------------*- C++ -*--===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines CXXSelfAssignmentChecker, which tests all custom defined
+// copy and move assignment operators for the case of self assignment, thus
+// where the parameter refers to the same location where the this pointer
+// points to. The checker itself does not do any checks at all, but it
+// causes the analyzer to check every copy and move assignment operator twice:
+// once for when 'this' aliases with the parameter and once for when it may not.
+// It is the task of the other enabled checkers to find the bugs in these two
+// different cases.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+
+class CXXSelfAssignmentChecker : public Checker<check::BeginFunction> {
+public:
+  CXXSelfAssignmentChecker();
+  void checkBeginFunction(CheckerContext &C) const;
+};
+}
+
+CXXSelfAssignmentChecker::CXXSelfAssignmentChecker() {}
+
+void CXXSelfAssignmentChecker::checkBeginFunction(CheckerContext &C) const {
+  if (!C.inTopFrame())
+    return;
+  const auto *LCtx = C.getLocationContext();
+  const auto *MD = dyn_cast<CXXMethodDecl>(LCtx->getDecl());
+  if (!MD)
+    return;
+  if (!MD->isCopyAssignmentOperator() && !MD->isMoveAssignmentOperator())
+    return;
+  auto &State = C.getState();
+  auto &SVB = C.getSValBuilder();
+  auto ThisVal =
+      State->getSVal(SVB.getCXXThis(MD, LCtx->getStackFrame()));
+  auto Param = SVB.makeLoc(State->getRegion(MD->getParamDecl(0), LCtx));
+  auto ParamVal = State->getSVal(Param);
+
+  ProgramStateRef SelfAssignState = State->bindLoc(Param, ThisVal, LCtx);
+  const NoteTag *SelfAssignTag =
+    C.getNoteTag([MD](BugReport &BR) -> std::string {
+        SmallString<256> Msg;
+        llvm::raw_svector_ostream Out(Msg);
+        Out << "Assuming " << MD->getParamDecl(0)->getName() << " == *this";
+        return Out.str();
+      });
+  C.addTransition(SelfAssignState, SelfAssignTag);
+
+  ProgramStateRef NonSelfAssignState = State->bindLoc(Param, ParamVal, LCtx);
+  const NoteTag *NonSelfAssignTag =
+    C.getNoteTag([MD](BugReport &BR) -> std::string {
+        SmallString<256> Msg;
+        llvm::raw_svector_ostream Out(Msg);
+        Out << "Assuming " << MD->getParamDecl(0)->getName() << " != *this";
+        return Out.str();
+      });
+  C.addTransition(NonSelfAssignState, NonSelfAssignTag);
+}
+
+void ento::registerCXXSelfAssignmentChecker(CheckerManager &Mgr) {
+  Mgr.registerChecker<CXXSelfAssignmentChecker>();
+}
+
+bool ento::shouldRegisterCXXSelfAssignmentChecker(const LangOptions &LO) {
+  return true;
+}