1 files changed, 168 insertions, 0 deletions
diff --git a/compilerplugins/clang/staticdynamic.cxx b/compilerplugins/clang/staticdynamic.cxx
new file mode 100644
index 000000000..6dc351546
--- /dev/null
+++ b/compilerplugins/clang/staticdynamic.cxx
@@ -0,0 +1,168 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * 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/.
+ */
+#ifndef LO_CLANG_SHARED_PLUGINS
+
+#include <cassert>
+#include <string>
+#include <iostream>
+#include <fstream>
+#include <map>
+#include <vector>
+
+#include "config_clang.h"
+
+#include "check.hxx"
+#include "plugin.hxx"
+
+namespace
+{
+class StaticDynamic : public loplugin::FilteringPlugin<StaticDynamic>
+{
+public:
+    explicit StaticDynamic(loplugin::InstantiationData const& data)
+        : FilteringPlugin(data)
+    {
+    }
+
+    bool preRun() override { return compiler.getLangOpts().CPlusPlus; }
+    void postRun() override {}
+    virtual void run() override
+    {
+        if (preRun())
+            TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+    }
+
+    bool VisitCXXDynamicCastExpr(CXXDynamicCastExpr const*);
+    bool VisitCXXStaticCastExpr(CXXStaticCastExpr const*);
+    bool PreTraverseCompoundStmt(CompoundStmt*);
+    bool PostTraverseCompoundStmt(CompoundStmt*, bool);
+    bool TraverseCompoundStmt(CompoundStmt*);
+
+private:
+    // the key is the pair of VarDecl and the type being cast to.
+    struct BlockState
+    {
+        std::map<std::pair<VarDecl const*, clang::Type const*>, SourceLocation> staticCastVars;
+        std::map<std::pair<VarDecl const*, clang::Type const*>, SourceLocation> dynamicCastVars;
+    };
+    // only maintain state inside a single basic block, we're not trying to analyse
+    // cross-block interactions.
+    std::vector<BlockState> blockStack;
+    BlockState blockState;
+};
+
+bool StaticDynamic::PreTraverseCompoundStmt(CompoundStmt*)
+{
+    blockStack.push_back(std::move(blockState));
+    return true;
+}
+
+bool StaticDynamic::PostTraverseCompoundStmt(CompoundStmt*, bool)
+{
+    blockState = std::move(blockStack.back());
+    blockStack.pop_back();
+    return true;
+}
+
+bool StaticDynamic::TraverseCompoundStmt(CompoundStmt* compoundStmt)
+{
+    bool ret = true;
+    if (PreTraverseCompoundStmt(compoundStmt))
+    {
+        ret = FilteringPlugin::TraverseCompoundStmt(compoundStmt);
+        PostTraverseCompoundStmt(compoundStmt, ret);
+    }
+    return ret;
+}
+
+const clang::Type* strip(QualType qt)
+{
+    const clang::Type* varType = qt->getUnqualifiedDesugaredType();
+    if (varType->isPointerType())
+        varType = varType->getPointeeType()->getUnqualifiedDesugaredType();
+    if (varType->isReferenceType())
+        varType = varType->getAs<clang::ReferenceType>()
+                      ->getPointeeType()
+                      ->getUnqualifiedDesugaredType();
+    return varType;
+}
+
+bool StaticDynamic::VisitCXXStaticCastExpr(CXXStaticCastExpr const* staticCastExpr)
+{
+    if (ignoreLocation(staticCastExpr))
+        return true;
+    auto subExprDecl = dyn_cast<DeclRefExpr>(staticCastExpr->getSubExpr()->IgnoreParenImpCasts());
+    if (!subExprDecl)
+        return true;
+    auto varDecl = dyn_cast_or_null<VarDecl>(subExprDecl->getDecl());
+    if (!varDecl)
+        return true;
+    auto varType = strip(staticCastExpr->getType());
+    auto it = blockState.dynamicCastVars.find({ varDecl, varType });
+    if (it != blockState.dynamicCastVars.end())
+    {
+        StringRef fn = getFilenameOfLocation(
+            compiler.getSourceManager().getSpellingLoc(staticCastExpr->getBeginLoc()));
+        // loop
+        if (loplugin::isSamePathname(fn, SRCDIR "/basctl/source/basicide/basobj3.cxx"))
+            return true;
+        if (loplugin::isSamePathname(fn, SRCDIR "/sw/source/core/doc/swserv.cxx"))
+            return true;
+        if (loplugin::isSamePathname(fn, SRCDIR "/sw/source/core/text/txtfly.cxx"))
+            return true;
+
+        report(DiagnosticsEngine::Warning, "static_cast after dynamic_cast",
+               staticCastExpr->getBeginLoc())
+            << staticCastExpr->getSourceRange();
+        report(DiagnosticsEngine::Note, "dynamic_cast here", it->second);
+        return true;
+    }
+    blockState.staticCastVars.insert({ { varDecl, varType }, staticCastExpr->getBeginLoc() });
+    return true;
+}
+
+bool StaticDynamic::VisitCXXDynamicCastExpr(CXXDynamicCastExpr const* dynamicCastExpr)
+{
+    if (ignoreLocation(dynamicCastExpr))
+        return true;
+
+    auto subExprDecl = dyn_cast<DeclRefExpr>(dynamicCastExpr->getSubExpr()->IgnoreParenImpCasts());
+    if (!subExprDecl)
+        return true;
+    auto varDecl = dyn_cast_or_null<VarDecl>(subExprDecl->getDecl());
+    if (!varDecl)
+        return true;
+    auto varType = strip(dynamicCastExpr->getTypeAsWritten());
+    auto it = blockState.staticCastVars.find({ varDecl, varType });
+    if (it != blockState.staticCastVars.end())
+    {
+        report(DiagnosticsEngine::Warning, "dynamic_cast after static_cast",
+               dynamicCastExpr->getBeginLoc())
+            << dynamicCastExpr->getSourceRange();
+        report(DiagnosticsEngine::Note, "static_cast here", it->second);
+        return true;
+    }
+    auto loc = dynamicCastExpr->getBeginLoc();
+    if (compiler.getSourceManager().isMacroArgExpansion(loc)
+        && (Lexer::getImmediateMacroNameForDiagnostics(loc, compiler.getSourceManager(),
+                                                       compiler.getLangOpts())
+            == "assert"))
+    {
+        return true;
+    }
+    blockState.dynamicCastVars.insert({ { varDecl, varType }, dynamicCastExpr->getBeginLoc() });
+    return true;
+}
+
+loplugin::Plugin::Registration<StaticDynamic> staticdynamic("staticdynamic");
+}
+
+#endif // LO_CLANG_SHARED_PLUGINS
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */