New loplugin:stdfunction

...finding dubious additions to namespace std (concentrating on functions for
now).  C++17 [namespace.std]/1: "The behavior of a C ++ program is undefined if
it adds declarations or definitions to namespace std or to a namespace within
namespace std unless otherwise specified."

This found

ad4c7b97752b4da73808402604d6f96b39d920f5 "Avoid declaring function templates in
namespace std"
042e30a3dc057aef4a02d95960e4dd4fb8d083ae "Avoid adding a function template
declaration to namespace std"
cae9240a76cdb0eeed92421930d3b4cbef0ac201 "Avoid adding a function declaration to
namespace std"

Change-Id: Ic2ba54e2a8bf931d5c58cedf499c0d1229eb2166
Reviewed-on: https://gerrit.libreoffice.org/78220
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/compilerplugins/clang/stdfunction.cxx b/compilerplugins/clang/stdfunction.cxx
new file mode 100644
index 000000000000..89935558d8a2
--- /dev/null
+++ b/compilerplugins/clang/stdfunction.cxx
@@ -0,0 +1,48 @@
+/* -*- 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"
+
+namespace
+{
+class StdFunction final : public loplugin::FilteringPlugin<StdFunction>
+{
+public:
+    explicit StdFunction(loplugin::InstantiationData const& data)
+        : FilteringPlugin(data)
+    {
+    }
+
+    bool VisitFunctionDecl(FunctionDecl const* decl)
+    {
+        if (ignoreLocation(decl))
+        {
+            return true;
+        }
+        if (!loplugin::ContextCheck(decl->getDeclContext()).StdOrNestedNamespace())
+        {
+            return true;
+        }
+        report(DiagnosticsEngine::Warning,
+               ("Do not declare a %select{function|function template|member function template"
+                " specialization|function template specialization}0 in namespace 'std'"),
+               decl->getLocation())
+            << decl->getTemplatedKind() << decl->getSourceRange();
+        return true;
+    }
+
+private:
+    void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
+};
+
+static loplugin::Plugin::Registration<StdFunction> X("stdfunction");
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */