1 files changed, 67 insertions, 0 deletions
diff --git a/clang/lib/StaticAnalyzer/Checkers/UndefinedArraySubscriptChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/UndefinedArraySubscriptChecker.cpp
new file mode 100644
index 000000000000..2f075eaeb03b
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/UndefinedArraySubscriptChecker.cpp
@@ -0,0 +1,67 @@
+//===--- UndefinedArraySubscriptChecker.h ----------------------*- 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 defines UndefinedArraySubscriptChecker, a builtin check in ExprEngine
+// that performs checks for undefined array subscripts.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/CheckerManager.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+class UndefinedArraySubscriptChecker
+  : public Checker< check::PreStmt<ArraySubscriptExpr> > {
+  mutable std::unique_ptr<BugType> BT;
+
+public:
+  void checkPreStmt(const ArraySubscriptExpr *A, CheckerContext &C) const;
+};
+} // end anonymous namespace
+
+void
+UndefinedArraySubscriptChecker::checkPreStmt(const ArraySubscriptExpr *A,
+                                             CheckerContext &C) const {
+  const Expr *Index = A->getIdx();
+  if (!C.getSVal(Index).isUndef())
+    return;
+
+  // Sema generates anonymous array variables for copying array struct fields.
+  // Don't warn if we're in an implicitly-generated constructor.
+  const Decl *D = C.getLocationContext()->getDecl();
+  if (const CXXConstructorDecl *Ctor = dyn_cast<CXXConstructorDecl>(D))
+    if (Ctor->isDefaulted())
+      return;
+
+  ExplodedNode *N = C.generateErrorNode();
+  if (!N)
+    return;
+  if (!BT)
+    BT.reset(new BuiltinBug(this, "Array subscript is undefined"));
+
+  // Generate a report for this bug.
+  auto R = std::make_unique<PathSensitiveBugReport>(*BT, BT->getDescription(), N);
+  R->addRange(A->getIdx()->getSourceRange());
+  bugreporter::trackExpressionValue(N, A->getIdx(), *R);
+  C.emitReport(std::move(R));
+}
+
+void ento::registerUndefinedArraySubscriptChecker(CheckerManager &mgr) {
+  mgr.registerChecker<UndefinedArraySubscriptChecker>();
+}
+
+bool ento::shouldRegisterUndefinedArraySubscriptChecker(const LangOptions &LO) {
+  return true;
+}