New loplugin:privatebase

...to flag places that implicitly derive a class privately instead of publicly,
where accidental private derivation can cause unexpected failure of
dynamic_cast, cf. 63b67ab5cab8cf7576a68cabe5fb1a42c6ad800c "Use public
derivation, and remove then-unnecessary downcasts."

Change-Id: I4bcd5c79c7e27380c820e2dd072fa4c4e8980078

1 files changed, 54 insertions, 0 deletions

diff --git a/compilerplugins/clang/privatebase.cxx b/compilerplugins/clang/privatebase.cxx
new file mode 100644
index 000000000000..8084ee34104b
--- /dev/null
+++ b/compilerplugins/clang/privatebase.cxx
@@ -0,0 +1,54 @@
+/* -*- 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/.
+ */
+
+#include "plugin.hxx"
+
+namespace {
+
+class PrivateBase:
+    public RecursiveASTVisitor<PrivateBase>, public loplugin::Plugin
+{
+public:
+    explicit PrivateBase(InstantiationData const & data): Plugin(data) {}
+
+    void run() override;
+
+    bool VisitCXXRecordDecl(CXXRecordDecl const * decl);
+};
+
+void PrivateBase::run() {
+    if (compiler.getLangOpts().CPlusPlus) {
+        TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+    }
+}
+
+bool PrivateBase::VisitCXXRecordDecl(CXXRecordDecl const * decl) {
+    if (ignoreLocation(decl) || !decl->isThisDeclarationADefinition()
+        || decl->getTagKind() != TTK_Class)
+    {
+        return true;
+    }
+    for (auto const & i: decl->bases()) {
+        if (i.getAccessSpecifierAsWritten() == AS_none) {
+            report(
+                DiagnosticsEngine::Warning,
+                "base class is private by default; explicitly give an access"
+                    " specifier",
+                i.getLocStart())
+                << i.getSourceRange();
+        }
+    }
+    return true;
+}
+
+loplugin::Plugin::Registration<PrivateBase> X("privatebase");
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */