loplugin:deletedspecial to help add SAL_DELETED_FUNCTION annotations

...to special member function declarations that were left undefined.  Helps
compilers do a better job at identifiying unused class members.  This plugin
uses heuristics and whitelists do identify applicable declarations, but is not
appropriate for "unattended" use so is placed into store/.

The following commits contain the results of running this plugin, per module:

* Declarations of undefined special member functions are mmarked
  SAL_DELETED_FUNCTION (aka "= delete", which is deemed superior to deriving the
  class from boost::noncopyable, cf. Howard Hinnant's reply to
  <http://stackoverflow.com/questions/7823990/what-are-the-advantages-of-boostnoncopyable>.

* Any redundant "explicit" or SAL_DLLPRIVATE markers are removed from the
  deleted definitions.

* Some redundant declarations of undefined default ctors are simply removed;
  smelled like clueless cargo-cult to have them declared at all.

* Some declarations of undefined operator == etc. are left in (and marked
  SAL_DELETED_FUNCTION) for now, to be on the safe side, though they are likely
  clueless cargo-cult, too.

* Most "static-only" classes are replaced with namespaces (and some where that
  would be non-trivial due to private members are marked TODO for later).

* Newly identified unused class members are removed.

Change-Id: Ibeaae4fd579d7a0971a2c2a654a2263acd13414a

compilerplugins/clang/store/deletedspecial.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 <iterator>
+#include <string>
+
+#include "compat.hxx"
+#include "plugin.hxx"
+
+// Second-guess that certain private special member function declarations for
+// which no definition can be found are left undefined to prevent them from
+// being implicitly declared.  Such situations are better expressed by marking
+// the function as SAL_DELETED_FUNCTION (it e.g. helps compilers determine
+// whether class members are unused if all of a class's member definitions are
+// seen in a compilation unit).  (Default constructors for classes with multiple
+// constructors are exempted as they would not be implicitly declared.
+// Destructors are exempted because it is likely that a destructor is defined
+// private on purpose.)
+
+namespace {
+
+CXXRecordDecl const * getClass(CXXMethodDecl const * decl) {
+    CXXRecordDecl const * cls = dyn_cast<CXXRecordDecl>(decl->getDeclContext());
+    assert(cls != nullptr);
+    return cls;
+}
+
+class DeletedSpecial:
+    public RecursiveASTVisitor<DeletedSpecial>, public loplugin::Plugin
+{
+public:
+    explicit DeletedSpecial(InstantiationData const & data): Plugin(data) {}
+
+    virtual void run() override;
+
+    bool VisitCXXMethodDecl(CXXMethodDecl const * decl);
+
+private:
+    bool whitelist(
+        CXXMethodDecl const * decl, std::string const & name,
+        std::string const & path);
+};
+
+void DeletedSpecial::run() {
+    if (compiler.getLangOpts().CPlusPlus
+        && compiler.getPreprocessor().getIdentifierInfo(
+            "LIBO_INTERNAL_ONLY")->hasMacroDefinition())
+    {
+        TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+    }
+}
+
+bool DeletedSpecial::VisitCXXMethodDecl(CXXMethodDecl const * decl) {
+    if (ignoreLocation(decl) || !compat::isFirstDecl(*decl) || decl->isDefined()
+        || decl->isDefaulted() || decl->getAccess() != AS_private)
+    {
+        return true;
+    }
+    std::string desc;
+    if (decl->isCopyAssignmentOperator()) {
+        if (whitelist(decl, "ImpGraphic", "vcl/inc/impgraph.hxx")
+            || whitelist(decl, "SwSubFont", "sw/source/core/inc/swfont.hxx"))
+        {
+            return true;
+        }
+        desc = "copy assignment operator";
+    } else if (decl->isMoveAssignmentOperator()) {
+        desc = "move assignment operator";
+    } else {
+        CXXConstructorDecl const * ctor = dyn_cast<CXXConstructorDecl>(decl);
+        CXXRecordDecl const * cls = getClass(decl);
+        if (ctor != nullptr && ctor->isCopyConstructor()) {
+            if (whitelist(decl, "ImpGraphic", "vcl/inc/impgraph.hxx")
+                || whitelist(decl, "SbMethod", "include/basic/sbmeth.hxx")
+                || whitelist(decl, "ScDBCollection::NamedDBs", "sc/inc/dbdata.hxx")
+                || whitelist(decl, "ScDrawPage", "sc/inc/drawpage.hxx")
+                || whitelist(decl, "ScFormEditData", "sc/source/ui/inc/formdata.hxx")
+                || whitelist(decl, "SmEditSource", "starmath/source/accessibility.hxx")
+                || whitelist(decl, "SwChartDataSequence", "sw/inc/unochart.hxx")
+                || whitelist(decl, "SwDPage", "sw/inc/dpage.hxx")
+                || whitelist(decl, "SwRedlineExtraData_Format", "sw/inc/redline.hxx")
+                || whitelist(decl, "SwRedlineExtraData_FormattingChanges", "sw/inc/redline.hxx")
+                || whitelist(decl, "SwTextAPIEditSource", "sw/source/core/inc/textapi.hxx")
+                || whitelist(decl, "XclImpBiff5Decrypter", "sc/source/filter/inc/xistream.hxx")
+                || whitelist(decl, "XclImpBiff8Decrypter", "sc/source/filter/inc/xistream.hxx")
+                || whitelist(decl, "configmgr::LocalizedPropertyNode", "configmgr/source/localizedpropertynode.hxx")
+                || whitelist(decl, "configmgr::LocalizedValueNode", "configmgr/source/localizedvaluenode.hxx")
+                || whitelist(decl, "configmgr::PropertyNode", "configmgr/source/propertynode.hxx")
+                || whitelist(decl, "oox::xls::BiffDecoder_RCF", "sc/source/filter/inc/biffcodec.hxx")
+                || whitelist(decl, "oox::xls::BiffDecoder_XOR", "sc/source/filter/inc/biffcodec.hxx")
+                || whitelist(decl, "rptui::OReportPage", "reportdesign/inc/RptPage.hxx"))
+            {
+                return true;
+            }
+            desc = "copy constructor";
+        } else if (ctor != nullptr && ctor->isMoveConstructor()) {
+            desc = "move constructor";
+        } else if (ctor != nullptr && ctor->isDefaultConstructor()
+                   && std::distance(cls->ctor_begin(), cls->ctor_end()) == 1)
+        {
+            if (whitelist(decl, "DocTemplLocaleHelper", "sfx2/source/doc/doctemplateslocal.hxx")
+                || whitelist(decl, "ScViewDataTable", "sc/source/filter/excel/../../ui/inc/viewdata.hxx")
+                || whitelist(decl, "ScViewDataTable", "sc/source/ui/inc/viewdata.hxx")
+                || whitelist(decl, "SwLineInfo", "sw/source/core/text/inftxt.hxx")
+                || whitelist(decl, "XRenderPeer", "vcl/unx/generic/gdi/xrender_peer.hxx")
+                || whitelist(decl, "desktop::OfficeIPCThread", "desktop/source/app/officeipcthread.hxx")
+                || whitelist(decl, "desktop::OfficeIPCThread", "desktop/source/lib/../app/officeipcthread.hxx")
+                || whitelist(decl, "sd::DiscoveryService", "sd/source/ui/remotecontrol/DiscoveryService.hxx")
+                || whitelist(decl, "sd::IconCache", "sd/source/ui/inc/tools/IconCache.hxx")
+                || whitelist(decl, "sd::slidesorter::cache::PageCacheManager", "sd/source/ui/slidesorter/inc/cache/SlsPageCacheManager.hxx")
+                || whitelist(decl, "sfx2::sidebar::CommandInfoProvider", "include/sfx2/sidebar/CommandInfoProvider.hxx")
+                || whitelist(decl, "writerfilter::ooxml::OOXMLFactory", "writerfilter/source/ooxml/OOXMLFactory.hxx"))
+            {
+                return true;
+            }
+            desc = "default constructor";
+        } else {
+            return true;
+        }
+    }
+    report(
+        DiagnosticsEngine::Warning,
+        ("private %0 is not defined at least in this compilation unit, maybe it"
+         " should be marked as deleted?"),
+        decl->getLocation())
+        << desc << decl->getSourceRange();
+    return true;
+}
+
+bool DeletedSpecial::whitelist(
+    CXXMethodDecl const * decl, std::string const & name,
+    std::string const & path)
+{
+    return getClass(decl)->getQualifiedNameAsString() == name
+        && (compiler.getSourceManager().getFilename(
+                compiler.getSourceManager().getSpellingLoc(decl->getLocation()))
+            == SRCDIR "/" + path);
+}
+
+loplugin::Plugin::Registration<DeletedSpecial> X("deletedspecial", true);
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */