[clang] [Webkit Checkers] Introduce a Webkit checker for memory unsafe casts (PR #114606)

[Ryosuke Niwa via cfe-commits]

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@@ -0,0 +1,86 @@
+//=======- MemoryUnsafeCastChecker.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 MemoryUnsafeCast checker, which checks for casts from a
+// base type to a derived type.
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/ASTContext.h"
+#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.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 MemoryUnsafeCastChecker : public Checker<check::PreStmt<CastExpr>> {
+  BugType BT{this, ""};
+
+public:
+  void checkPreStmt(const CastExpr *CE, CheckerContext &C) const;
+};
+} // end namespace
+
+void emitWarning(CheckerContext &C, const CastExpr &CE, const BugType &BT,
+                 QualType FromType, QualType ToType) {
+  ExplodedNode *errorNode = C.generateNonFatalErrorNode();
+  if (!errorNode)
+    return;
+  SmallString<192> Buf;
+  llvm::raw_svector_ostream OS(Buf);
+  OS << "Memory unsafe cast from base type '";
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rniwa wrote:

I don't think "Memory" is adding much value here. Maybe just say "unsafe cast"?

https://github.com/llvm/llvm-project/pull/114606