Extend loplugin:external to warn about classes

...following up on 314f15bff08b76bf96acf99141776ef64d2f1355 "Extend
loplugin:external to warn about enums".

Cases where free functions were moved into an unnamed namespace along with a
class, to not break ADL, are in:

  filter/source/svg/svgexport.cxx
  sc/source/filter/excel/xelink.cxx
  sc/source/filter/excel/xilink.cxx
  svx/source/sdr/contact/viewobjectcontactofunocontrol.cxx

All other free functions mentioning moved classes appear to be harmless and not
give rise to (silent, even) ADL breakage.  (One remaining TODO in
compilerplugins/clang/external.cxx is that derived classes are not covered by
computeAffectedTypes, even though they could also be affected by ADL-breakage---
but don't seem to be in any acutal case across the code base.)

For friend declarations using elaborate type specifiers, like

  class C1 {};
  class C2 { friend class C1; };

* If C2 (but not C1) is moved into an unnamed namespace, the friend declaration
must be changed to not use an elaborate type specifier (i.e., "friend C1;"; see
C++17 [namespace.memdef]/3: "If the name in a friend declaration is neither
qualified nor a template-id and the declaration is a function or an
elaborated-type-specifier, the lookup to determine whether the entity has been
previously declared shall not consider any scopes outside the innermost
enclosing namespace.")

* If C1 (but not C2) is moved into an unnamed namespace, the friend declaration
must be changed too, see <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71882>
"elaborated-type-specifier friend not looked up in unnamed namespace".

Apart from that, to keep changes simple and mostly mechanical (which should help
avoid regressions), out-of-line definitions of class members have been left in
the enclosing (named) namespace.  But explicit specializations of class
templates had to be moved into the unnamed namespace to appease
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92598> "explicit specialization of
template from unnamed namespace using unqualified-id in enclosing namespace".

Also, accompanying declarations (of e.g. typedefs or static variables) that
could arguably be moved into the unnamed namespace too have been left alone.

And in some cases, mention of affected types in blacklists in other loplugins
needed to be adapted.

And sc/qa/unit/mark_test.cxx uses a hack of including other .cxx, one of which
is sc/source/core/data/segmenttree.cxx where e.g. ScFlatUInt16SegmentsImpl is
not moved into an unnamed namespace (because it is declared in
sc/inc/segmenttree.hxx), but its base ScFlatSegmentsImpl is.  GCC warns about
such combinations with enabled-by-default -Wsubobject-linkage, but "The compiler
doesn’t give this warning for types defined in the main .C file, as those are
unlikely to have multiple definitions."
(<https://gcc.gnu.org/onlinedocs/gcc-9.2.0/gcc/Warning-Options.html>)  The
warned-about classes also don't have multiple definitions in the given test, so
disable the warning when including the .cxx.

Change-Id: Ib694094c0d8168be68f8fe90dfd0acbb66a3f1e4
Reviewed-on: https://gerrit.libreoffice.org/83239
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

5 files changed, 33 insertions, 0 deletions

diff --git a/cppuhelper/qa/ifcontainer/cppu_ifcontainer.cxx b/cppuhelper/qa/ifcontainer/cppu_ifcontainer.cxx
index 43a9d87df927..0dcebbbac16a 100644
--- a/cppuhelper/qa/ifcontainer/cppu_ifcontainer.cxx
+++ b/cppuhelper/qa/ifcontainer/cppu_ifcontainer.cxx
@@ -32,6 +32,8 @@ using namespace com::sun::star;
 using namespace com::sun::star::uno;
 using namespace com::sun::star::lang;
 
+namespace {
+
 struct ContainerStats {
     int m_nAlive;
     int m_nDisposed;
@@ -51,6 +53,8 @@ public:
     }
 };
 
+}
+
 namespace cppu_ifcontainer
 {
     class IfTest : public CppUnit::TestFixture
diff --git a/cppuhelper/source/component_context.cxx b/cppuhelper/source/component_context.cxx
index 5d6294704f7f..6d70b7817fa7 100644
--- a/cppuhelper/source/component_context.cxx
+++ b/cppuhelper/source/component_context.cxx
@@ -72,6 +72,8 @@ static void try_dispose( Reference< lang::XComponent > const & xComp )
     }
 }
 
+namespace {
+
 class DisposingForwarder
     : public WeakImplHelper< lang::XEventListener >
 {
@@ -91,6 +93,8 @@ public:
     virtual void SAL_CALL disposing( lang::EventObject const & rSource ) override;
 };
 
+}
+
 inline void DisposingForwarder::listen(
     Reference< lang::XComponent > const & xSource,
     Reference< lang::XComponent > const & xTarget )
@@ -107,6 +111,7 @@ void DisposingForwarder::disposing( lang::EventObject const & )
     m_xTarget.clear();
 }
 
+namespace {
 
 struct MutexHolder
 {
@@ -167,6 +172,8 @@ public:
     virtual sal_Bool SAL_CALL hasElements() override;
 };
 
+}
+
 // XNameContainer
 
 void ComponentContext::insertByName(
diff --git a/cppuhelper/source/factory.cxx b/cppuhelper/source/factory.cxx
index d61639566110..8a951033cc08 100644
--- a/cppuhelper/source/factory.cxx
+++ b/cppuhelper/source/factory.cxx
@@ -54,6 +54,8 @@ using namespace com::sun::star::registry;
 namespace cppu
 {
 
+namespace {
+
 class OSingleFactoryHelper
     : public XServiceInfo
     , public XSingleServiceFactory
@@ -113,6 +115,9 @@ protected:
     Sequence< OUString >             aServiceNames;
     OUString                         aImplementationName;
 };
+
+}
+
 OSingleFactoryHelper::~OSingleFactoryHelper()
 {
 }
@@ -222,6 +227,8 @@ Sequence< OUString > OSingleFactoryHelper::getSupportedServiceNames()
     return aServiceNames;
 }
 
+namespace {
+
 struct OFactoryComponentHelper_Mutex
 {
     Mutex   aMutex;
@@ -285,6 +292,7 @@ protected:
     bool isInstance() const {return xTheInstance.is();}
 };
 
+}
 
 Any SAL_CALL OFactoryComponentHelper::queryInterface( const Type & rType )
 {
@@ -426,6 +434,8 @@ sal_Bool SAL_CALL OFactoryComponentHelper::releaseOnNotification()
     return true;
 }
 
+namespace {
+
 class ORegistryFactoryHelper : public OFactoryComponentHelper,
                                public OPropertySetHelper
 
@@ -495,6 +505,8 @@ protected:
     using OPropertySetHelper::getTypes;
 };
 
+}
+
 // XInterface
 
 Any SAL_CALL ORegistryFactoryHelper::queryInterface(
@@ -800,6 +812,8 @@ sal_Bool SAL_CALL ORegistryFactoryHelper::releaseOnNotification()
     return retVal;
 }
 
+namespace {
+
 class OFactoryProxyHelper : public WeakImplHelper< XServiceInfo, XSingleServiceFactory,
                                                     XUnloadingPreference >
 {
@@ -824,6 +838,8 @@ public:
 
 };
 
+}
+
 // XSingleServiceFactory
 Reference<XInterface > OFactoryProxyHelper::createInstance()
 {
diff --git a/cppuhelper/source/propshlp.cxx b/cppuhelper/source/propshlp.cxx
index 3f39522b008c..53aeb8f4d4b1 100644
--- a/cppuhelper/source/propshlp.cxx
+++ b/cppuhelper/source/propshlp.cxx
@@ -67,6 +67,8 @@ static int compare_OUString_Property_Impl( const void *arg1, const void *arg2 )
  * The class which implements the PropertySetInfo interface.
  */
 
+namespace {
+
 class OPropertySetHelperInfo_Impl
     : public WeakImplHelper< css::beans::XPropertySetInfo >
 {
@@ -81,6 +83,7 @@ public:
     virtual sal_Bool SAL_CALL hasPropertyByName(const OUString& PropertyName) override;
 };
 
+}
 
 /**
  * Create an object that implements XPropertySetInfo IPropertyArrayHelper.
diff --git a/cppuhelper/source/tdmgr.cxx b/cppuhelper/source/tdmgr.cxx
index 8666fadc6554..970688d736b6 100644
--- a/cppuhelper/source/tdmgr.cxx
+++ b/cppuhelper/source/tdmgr.cxx
@@ -597,6 +597,7 @@ static void typelib_callback(
 }
 }
 
+namespace {
 
 class EventListenerImpl
     : public WeakImplHelper< lang::XEventListener >
@@ -613,6 +614,8 @@ public:
     virtual void SAL_CALL disposing( lang::EventObject const & rEvt ) override;
 };
 
+}
+
 void EventListenerImpl::disposing( lang::EventObject const & rEvt )
 {
     if (rEvt.Source != m_xTDMgr) {