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>

7 files changed, 35 insertions, 1 deletions

diff --git a/svtools/source/misc/acceleratorexecute.cxx b/svtools/source/misc/acceleratorexecute.cxx
index a9e44ba6a9f8..3648e200e7c2 100644
--- a/svtools/source/misc/acceleratorexecute.cxx
+++ b/svtools/source/misc/acceleratorexecute.cxx
@@ -38,6 +38,8 @@
 namespace svt
 {
 
+namespace {
+
 class AsyncAccelExec : public cppu::WeakImplHelper<css::lang::XEventListener>
 {
     private:
@@ -77,6 +79,7 @@ class AsyncAccelExec : public cppu::WeakImplHelper<css::lang::XEventListener>
         DECL_LINK(impl_ts_asyncCallback, LinkParamNone*, void);
 };
 
+}
 
 AcceleratorExecute::AcceleratorExecute()
     : TMutexInit()
diff --git a/svtools/source/misc/embedhlp.cxx b/svtools/source/misc/embedhlp.cxx
index 3e270f0e8d60..2319485a65bd 100644
--- a/svtools/source/misc/embedhlp.cxx
+++ b/svtools/source/misc/embedhlp.cxx
@@ -58,6 +58,8 @@ using namespace com::sun::star;
 
 namespace svt {
 
+namespace {
+
 class EmbedEventListener_Impl : public ::cppu::WeakImplHelper < embed::XStateChangeListener,
                                                                  document::XEventListener,
                                                                  util::XModifyListener,
@@ -83,6 +85,8 @@ public:
     virtual void SAL_CALL modified( const css::lang::EventObject& aEvent ) override;
 };
 
+}
+
 rtl::Reference<EmbedEventListener_Impl> EmbedEventListener_Impl::Create( EmbeddedObjectRef* p )
 {
     rtl::Reference<EmbedEventListener_Impl> pRet(new EmbedEventListener_Impl( p ));
diff --git a/svtools/source/misc/imagemgr.cxx b/svtools/source/misc/imagemgr.cxx
index 5fc3456d0bbd..0a36573bb9b5 100644
--- a/svtools/source/misc/imagemgr.cxx
+++ b/svtools/source/misc/imagemgr.cxx
@@ -43,6 +43,8 @@
 #define NO_INDEX        (-1)
 #define CONTENT_HELPER  ::utl::UCBContentHelper
 
+namespace {
+
 struct SvtExtensionResIdMapping_Impl
 {
     const char* _pExt;
@@ -51,6 +53,8 @@ struct SvtExtensionResIdMapping_Impl
     SvImageId const   _nImgId;
 };
 
+}
+
 static SvtExtensionResIdMapping_Impl const ExtensionMap_Impl[] =
 {
     { "awk",   true,  STR_DESCRIPTION_SOURCEFILE,            SvImageId::NONE },
@@ -166,12 +170,16 @@ static SvtExtensionResIdMapping_Impl const ExtensionMap_Impl[] =
     { nullptr, false, nullptr, SvImageId::NONE }
 };
 
+namespace {
+
 struct SvtFactory2ExtensionMapping_Impl
 {
     const char*   _pFactory;
     const char*   _pExtension;
 };
 
+}
+
 // mapping from "private:factory" url to extension
 
 static SvtFactory2ExtensionMapping_Impl const Fac2ExtMap_Impl[] =
diff --git a/svtools/source/misc/imageresourceaccess.cxx b/svtools/source/misc/imageresourceaccess.cxx
index 829ffdb5feb5..8f07e59b999b 100644
--- a/svtools/source/misc/imageresourceaccess.cxx
+++ b/svtools/source/misc/imageresourceaccess.cxx
@@ -40,6 +40,8 @@ using namespace css;
 
 typedef ::cppu::WeakImplHelper<io::XStream, io::XSeekable> StreamSupplier_Base;
 
+namespace {
+
 class StreamSupplier : public StreamSupplier_Base
 {
 private:
@@ -61,6 +63,8 @@ protected:
     virtual sal_Int64 SAL_CALL getLength() override;
 };
 
+}
+
 StreamSupplier::StreamSupplier(uno::Reference<io::XInputStream> const & rxInput, uno::Reference<io::XOutputStream> const & rxOutput)
     : m_xInput(rxInput)
     , m_xOutput(rxOutput)
diff --git a/svtools/source/misc/langhelp.cxx b/svtools/source/misc/langhelp.cxx
index bedd8d1205c5..b3df64fce1a1 100644
--- a/svtools/source/misc/langhelp.cxx
+++ b/svtools/source/misc/langhelp.cxx
@@ -64,6 +64,8 @@ OUString getInstalledLocaleForLanguage(css::uno::Sequence<OUString> const & inst
 
 static std::unique_ptr<Idle> xLangpackInstaller;
 
+namespace {
+
 class InstallLangpack : public Idle
 {
     std::vector<OUString> const m_aPackages;
@@ -99,6 +101,8 @@ public:
     }
 };
 
+}
+
 OUString getInstalledLocaleForSystemUILanguage(const css::uno::Sequence<OUString>& rLocaleElementNames, bool bRequestInstallIfMissing, const OUString& rPreferredLocale)
 {
     OUString wantedLocale(rPreferredLocale);
diff --git a/svtools/source/misc/langtab.cxx b/svtools/source/misc/langtab.cxx
index 2b4311cde7f6..7c655b1f04f6 100644
--- a/svtools/source/misc/langtab.cxx
+++ b/svtools/source/misc/langtab.cxx
@@ -37,6 +37,8 @@
 
 using namespace ::com::sun::star;
 
+namespace {
+
 class SvtLanguageTableImpl
 {
 private:
@@ -71,7 +73,6 @@ public:
     }
 };
 
-namespace {
 struct theLanguageTable : public rtl::Static< SvtLanguageTableImpl, theLanguageTable > {};
 }
 
diff --git a/svtools/source/misc/templatefoldercache.cxx b/svtools/source/misc/templatefoldercache.cxx
index 7048441ecf8a..36761da02577 100644
--- a/svtools/source/misc/templatefoldercache.cxx
+++ b/svtools/source/misc/templatefoldercache.cxx
@@ -93,11 +93,18 @@ namespace svt
 
     //= TemplateContent
 
+    namespace {
+
     struct TemplateContent;
+
+    }
+
     typedef ::std::vector< ::rtl::Reference< TemplateContent > >    TemplateFolderContent;
     typedef TemplateFolderContent::const_iterator           ConstFolderIterator;
     typedef TemplateFolderContent::iterator                 FolderIterator;
 
+    namespace {
+
     /** a struct describing one content in one of the template dirs (or at least it's relevant aspects)
     */
     struct TemplateContent : public ::salhelper::SimpleReferenceObject
@@ -138,6 +145,7 @@ namespace svt
                                                         { m_aSubContents.push_back( _rxNewElement ); }
     };
 
+    }
 
     TemplateContent::TemplateContent( const INetURLObject& _rURL )
         :m_aURL( _rURL )
@@ -154,6 +162,7 @@ namespace svt
 
     //= stl helpers
 
+    namespace {
 
     /// compares two TemplateContent by URL
     struct TemplateContentURLLess
@@ -365,6 +374,7 @@ namespace svt
         }
     };
 
+    }
 
     //= TemplateFolderCacheImpl