new loplugin:dodgyswitch

and fix bug in ScriptDocument::getTitle
which has been there since

    commit e304ba66
    Date:   Thu Mar 15 14:59:30 2007 +0000
    INTEGRATION: CWS basmgr02 (1.1.2); FILE ADDED

plugin is off by default since it uses expensive parentStmt() calls

Change-Id: Id0f16baec48e0381e0083594d7e59b58b023da2f
Reviewed-on: https://gerrit.libreoffice.org/43750Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

basctl/source/basicide/scriptdocument.cxx

@@ -1475,6 +1475,7 @@ namespace basctl
                 case LibraryType::All:      aTitle = IDEResId(RID_STR_USERMACROSDIALOGS); break;
                 default:
                     break;
+                }
             }
             break;
             case LIBRARY_LOCATION_SHARE:
@@ -1494,7 +1495,6 @@ namespace basctl
                 break;
             default:
                 break;
-            }
         }
 
         return aTitle;

compilerplugins/clang/dodgyswitch.cxx

+/* -*- 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 <cassert>
+#include <string>
+#include <iostream>
+#include <fstream>
+#include <set>
+#include "plugin.hxx"
+
+namespace {
+
+class DodgySwitch:
+    public RecursiveASTVisitor<DodgySwitch>, public loplugin::Plugin
+{
+public:
+    explicit DodgySwitch(InstantiationData const & data): Plugin(data) {}
+
+    virtual void run() override
+    {
+        TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+    }
+
+    bool VisitDefaultStmt(DefaultStmt const * );
+    bool VisitCaseStmt(CaseStmt const * );
+private:
+    bool IsParentSwitch(Stmt const * );
+};
+
+bool DodgySwitch::VisitDefaultStmt(DefaultStmt const * defaultStmt)
+{
+    if (ignoreLocation(defaultStmt))
+        return true;
+    if (!IsParentSwitch(defaultStmt))
+        report(
+            DiagnosticsEngine::Warning, "default statement not directly under switch",
+            defaultStmt->getLocStart())
+          << defaultStmt->getSourceRange();
+    return true;
+}
+
+bool DodgySwitch::VisitCaseStmt(CaseStmt const * caseStmt)
+{
+    if (ignoreLocation(caseStmt))
+        return true;
+    if (!IsParentSwitch(caseStmt))
+    {
+        //parentStmt(parentStmt(caseStmt))->dump();
+        report(
+            DiagnosticsEngine::Warning, "case statement not directly under switch",
+            caseStmt->getLocStart())
+          << caseStmt->getSourceRange();
+    }
+    return true;
+}
+
+bool DodgySwitch::IsParentSwitch(Stmt const * stmt)
+{
+    auto parent = parentStmt(stmt);
+    if (isa<CaseStmt>(parent) || isa<DefaultStmt>(parent)) // daisy chain
+        return true;
+    auto compoundStmt = dyn_cast<CompoundStmt>(parent);
+    if (!compoundStmt)
+        return false;
+    return isa<SwitchStmt>(parentStmt(compoundStmt));
+}
+
+loplugin::Plugin::Registration< DodgySwitch > X("dodgyswitch", false);
+
+}
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */

compilerplugins/clang/test/dodgyswitch.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/types.h>
+
+int foo();
+
+int main() {
+    switch (foo())
+    {
+        case 1: { break; }
+        case 2: {
+            SAL_FALLTHROUGH;
+            {
+                case 3: // expected-error {{case statement not directly under switch [loplugin:dodgyswitch]}}
+                break;
+            }
+            default: // expected-error {{default statement not directly under switch [loplugin:dodgyswitch]}}
+            break;
+        }
+    }
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */

solenv/CompilerTest_compilerplugins_clang.mk

@@ -18,6 +18,7 @@ $(eval $(call gb_CompilerTest_add_exception_objects,compilerplugins_clang, \
     $(if $(filter-out INTEL,$(CPU)),compilerplugins/clang/test/convertuintptr) \
     compilerplugins/clang/test/cppunitassertequals \
     compilerplugins/clang/test/datamembershadow \
+    compilerplugins/clang/test/dodgyswitch \
     compilerplugins/clang/test/droplong \
     compilerplugins/clang/test/externvar \
     compilerplugins/clang/test/expressionalwayszero \