Fix loplugin::unusedvariablecheck check for std classes

(but which finds no new hits)

Change-Id: I862a3c82932ee6d6d0946cd33f965bb8e917cff8

compilerplugins/clang/check.cxx

@@ -216,14 +216,9 @@ bool isExtraWarnUnusedType(clang::QualType type) {
     }
     auto const tc = TypeCheck(rec);
     // Check some common non-LO types:
-    if (tc.Class("string").Namespace("std").GlobalNamespace()
-        || tc.Class("basic_string").Namespace("std").GlobalNamespace()
-        || tc.Class("list").Namespace("std").GlobalNamespace()
-        || (tc.Class("list").Namespace("__debug").Namespace("std")
-            .GlobalNamespace())
-        || tc.Class("vector").Namespace("std").GlobalNamespace()
-        || (tc.Class("vector" ).Namespace("__debug").Namespace("std")
-            .GlobalNamespace()))
+    if (tc.Class("basic_string").StdNamespace()
+        || tc.Class("list").StdNamespace()
+        || tc.Class("vector").StdNamespace())
     {
         return true;
     }

compilerplugins/clang/test/unusedvariablecheck.cxx

+/* -*- 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 <list>
+#include <string>
+#include <vector>
+
+namespace
+{
+template <typename T> using Vec = std::vector<T>;
+}
+
+int main()
+{
+    std::list<int> v1; // expected-error {{unused variable 'v1' [loplugin:unusedvariablecheck]}}
+    std::string v2; // expected-error {{unused variable 'v2' [loplugin:unusedvariablecheck]}}
+    Vec<int> v3; // expected-error {{unused variable 'v3' [loplugin:unusedvariablecheck]}}
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */