new loplugin:unoquery

look for places we are doing code like:

    Reference<XProperty>(model, css::uno::UNO_QUERY)->getAsProperty()

which might result in a SIGSEGV is the query fails

Change-Id: I5cbdbc9e64bd0bed588297c512bf60cbacb9442e
Reviewed-on: https://gerrit.libreoffice.org/69044
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

2 files changed, 106 insertions, 0 deletions

diff --git a/compilerplugins/clang/test/unoquery.cxx b/compilerplugins/clang/test/unoquery.cxx
new file mode 100644
index 000000000000..a80786a176c3
--- /dev/null
+++ b/compilerplugins/clang/test/unoquery.cxx
@@ -0,0 +1,19 @@
+/* -*- 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 "sal/config.h"
+#include "com/sun/star/beans/XProperty.hpp"
+
+void foo(css::uno::Reference<css::uno::XInterface> model)
+{
+    css::uno::Reference<css::beans::XProperty>(model, css::uno::UNO_QUERY)->getAsProperty();
+    // expected-error@-1 {{calling UNO_QUERY followed by unconditional method call might result in SIGSEGV, rather use UNO_QUERY_THROW [loplugin:unoquery]}}
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
diff --git a/compilerplugins/clang/unoquery.cxx b/compilerplugins/clang/unoquery.cxx
new file mode 100644
index 000000000000..ad9d2aada4e9
--- /dev/null
+++ b/compilerplugins/clang/unoquery.cxx
@@ -0,0 +1,87 @@
+/* -*- 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 "check.hxx"
+#include "plugin.hxx"
+
+// TODO it would be better if we were running some kind of nullability analysis here, where we marked
+// the results of expressions like Reference(..UNO_QUERY) as being nullable, and then looked for
+// places where we unconditionally deference the results of that expression.
+
+namespace
+{
+class UnoQuery : public loplugin::FilteringPlugin<UnoQuery>
+{
+public:
+    explicit UnoQuery(loplugin::InstantiationData const& data)
+        : FilteringPlugin(data)
+    {
+    }
+
+    void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
+    bool VisitCXXMemberCallExpr(CXXMemberCallExpr const*);
+};
+
+bool UnoQuery::VisitCXXMemberCallExpr(CXXMemberCallExpr const* memberCallExpr)
+{
+    if (ignoreLocation(memberCallExpr))
+        return true;
+
+    memberCallExpr->dump();
+
+    auto isXInterface = [](Decl const* decl) -> bool {
+        return bool(loplugin::DeclCheck(decl)
+                        .Class("XInterface")
+                        .Namespace("uno")
+                        .Namespace("star")
+                        .Namespace("sun")
+                        .Namespace("com")
+                        .GlobalNamespace());
+    };
+    if (!loplugin::isDerivedFrom(memberCallExpr->getRecordDecl(), isXInterface))
+        return true;
+    auto operatorCallExpr = dyn_cast<CXXOperatorCallExpr>(
+        memberCallExpr->getImplicitObjectArgument()->IgnoreImplicit());
+    if (!operatorCallExpr)
+        return true;
+
+    Expr const* expr = operatorCallExpr->getArg(0)->IgnoreImplicit();
+    // depending on the version of clang, the IgnoreImplicit may or may not look through these nodes
+    if (auto matTemp = dyn_cast<MaterializeTemporaryExpr>(expr))
+        expr = matTemp->GetTemporaryExpr();
+    if (auto bindTemp = dyn_cast<CXXBindTemporaryExpr>(expr))
+        expr = bindTemp->getSubExpr();
+
+    auto temporaryExpr = dyn_cast<CXXTemporaryObjectExpr>(expr);
+    if (!temporaryExpr)
+        return true;
+    if (temporaryExpr->getNumArgs() < 2)
+        return true;
+    auto declRefExpr = dyn_cast<DeclRefExpr>(temporaryExpr->getArg(1)->IgnoreImplicit());
+    if (!declRefExpr)
+        return true;
+    auto enumConstant = dyn_cast<EnumConstantDecl>(declRefExpr->getDecl());
+    if (!enumConstant)
+        return true;
+    if (enumConstant->getName() != "UNO_QUERY")
+        return true;
+
+    report(DiagnosticsEngine::Warning,
+           "calling UNO_QUERY followed by unconditional method call might result in SIGSEGV, "
+           "rather use UNO_QUERY_THROW",
+           memberCallExpr->getExprLoc())
+        << memberCallExpr->getSourceRange();
+
+    return true;
+}
+
+loplugin::Plugin::Registration<UnoQuery> unoquery("unoquery", true);
+};
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */