new loplugin:dbgunhandledexception

enforce that DBG_UNHANDLED_EXCEPTION is called first in a catch block,
otherwise it cannot do it's job properly

Change-Id: I906436c6861212c44f8f21552ccbceb54f15c6e1
Reviewed-on: https://gerrit.libreoffice.org/52303
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

2 files changed, 144 insertions, 0 deletions

diff --git a/compilerplugins/clang/dbgunhandledexception.cxx b/compilerplugins/clang/dbgunhandledexception.cxx
new file mode 100644
index 000000000000..54b00f57f758
--- /dev/null
+++ b/compilerplugins/clang/dbgunhandledexception.cxx
@@ -0,0 +1,107 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * Based on LLVM/Clang.
+ *
+ * This file is distributed under the University of Illinois Open Source
+ * License. See LICENSE.TXT for details.
+ *
+ */
+
+#include "check.hxx"
+#include "plugin.hxx"
+#include <clang/Lex/Lexer.h>
+#include <fstream>
+#include <set>
+
+namespace loplugin
+{
+/*
+This is a compile check.
+
+Check that DBG_UNHANDLED_EXCEPTION is always the first statement in a catch block, otherwise
+it does not work properly.
+*/
+
+class DbgUnhandledException : public RecursiveASTVisitor<DbgUnhandledException>, public Plugin
+{
+public:
+    explicit DbgUnhandledException(InstantiationData const& data);
+    virtual void run() override;
+    bool VisitCallExpr(CallExpr const* call);
+    bool TraverseCXXCatchStmt(CXXCatchStmt*);
+
+private:
+    CXXCatchStmt const* currCatchStmt = nullptr;
+};
+
+DbgUnhandledException::DbgUnhandledException(const InstantiationData& data)
+    : Plugin(data)
+{
+}
+
+void DbgUnhandledException::run()
+{
+    TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+}
+
+bool DbgUnhandledException::TraverseCXXCatchStmt(CXXCatchStmt* catchStmt)
+{
+    auto prevCatchStmt = currCatchStmt;
+    currCatchStmt = catchStmt;
+    auto rv = RecursiveASTVisitor::TraverseCXXCatchStmt(catchStmt);
+    currCatchStmt = prevCatchStmt;
+    return rv;
+}
+
+bool DbgUnhandledException::VisitCallExpr(const CallExpr* call)
+{
+    if (ignoreLocation(call))
+        return true;
+    const FunctionDecl* func = call->getDirectCallee();
+    if (!func)
+        return true;
+
+    if (!func->getIdentifier() || func->getName() != "DbgUnhandledException")
+        return true;
+
+    if (!currCatchStmt)
+    {
+        report(DiagnosticsEngine::Warning, "DBG_UNHANDLED_EXCEPTION outside catch block",
+               call->getLocStart());
+        return true;
+    }
+    auto catchBlock = dyn_cast<CompoundStmt>(currCatchStmt->getHandlerBlock());
+    if (!catchBlock)
+    {
+        report(DiagnosticsEngine::Warning,
+               "something wrong with DBG_UNHANDLED_EXCEPTION, no CompoundStmt?",
+               call->getLocStart());
+        return true;
+    }
+    if (catchBlock->size() < 1)
+    {
+        report(DiagnosticsEngine::Warning,
+               "something wrong with DBG_UNHANDLED_EXCEPTION, CompoundStmt size == 0?",
+               call->getLocStart());
+        return true;
+    }
+
+    Stmt const* firstStmt = *catchBlock->body_begin();
+    if (auto exprWithCleanups = dyn_cast<ExprWithCleanups>(firstStmt))
+        firstStmt = exprWithCleanups->getSubExpr();
+    if (firstStmt != call)
+    {
+        report(DiagnosticsEngine::Warning,
+               "DBG_UNHANDLED_EXCEPTION must be first statement in catch block",
+               call->getLocStart());
+    }
+    return true;
+}
+
+static Plugin::Registration<DbgUnhandledException> X("dbgunhandledexception");
+
+} // namespace
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/compilerplugins/clang/test/dbgunhandledexception.cxx b/compilerplugins/clang/test/dbgunhandledexception.cxx
new file mode 100644
index 000000000000..0abaef0dd06d
--- /dev/null
+++ b/compilerplugins/clang/test/dbgunhandledexception.cxx
@@ -0,0 +1,37 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * 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 <tools/diagnose_ex.h>
+
+void func1();
+
+int main()
+{
+    try
+    {
+        func1();
+    }
+    catch (std::exception const&)
+    {
+        SAL_WARN("xmloff", "message");
+        DBG_UNHANDLED_EXCEPTION(
+            "xmloff",
+            "message"); // expected-error@-2 {{DBG_UNHANDLED_EXCEPTION must be first statement in catch block [loplugin:dbgunhandledexception]}}
+    }
+    try
+    {
+        func1();
+    }
+    catch (std::exception const&)
+    {
+        DBG_UNHANDLED_EXCEPTION("xmloff", "message");
+    }
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */