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>

4 files changed, 16 insertions, 0 deletions

diff --git a/linguistic/source/convdicxml.cxx b/linguistic/source/convdicxml.cxx
index 979a33ab8464..ccd52688108e 100644
--- a/linguistic/source/convdicxml.cxx
+++ b/linguistic/source/convdicxml.cxx
@@ -68,6 +68,7 @@ static sal_Int16 GetConversionTypeFromText( const OUString &rText )
     return nRes;
 }
 
+namespace {
 
 class ConvDicXMLImportContext :
     public SvXMLImportContext
@@ -154,6 +155,7 @@ public:
     const OUString &    GetLeftText() const     { return rEntryContext.GetLeftText(); }
 };
 
+}
 
 void ConvDicXMLImportContext::characters(const OUString & /*rChars*/)
 {
diff --git a/linguistic/source/lngopt.cxx b/linguistic/source/lngopt.cxx
index e2d6d652460a..0bd9883f999e 100644
--- a/linguistic/source/lngopt.cxx
+++ b/linguistic/source/lngopt.cxx
@@ -78,12 +78,16 @@ LinguOptions::~LinguOptions()
     }
 }
 
+namespace {
+
 struct WID_Name
 {
     sal_Int32        nWID;
     const char  *pPropertyName;
 };
 
+}
+
 //! order of entries is import (see LinguOptions::GetName)
 //! since the WID is used as index in this table!
 WID_Name const aWID_Name[] =
diff --git a/linguistic/source/misc.cxx b/linguistic/source/misc.cxx
index ef64ac9d25b3..eb10b709e21d 100644
--- a/linguistic/source/misc.cxx
+++ b/linguistic/source/misc.cxx
@@ -58,11 +58,15 @@ using namespace com::sun::star::linguistic2;
 namespace linguistic
 {
 
+namespace {
+
 //!! multi-thread safe mutex for all platforms !!
 struct LinguMutex : public rtl::Static< osl::Mutex, LinguMutex >
 {
 };
 
+}
+
 osl::Mutex &    GetLinguMutex()
 {
     return LinguMutex::get();
@@ -115,6 +119,8 @@ static sal_Int32 Minimum( sal_Int32 n1, sal_Int32 n2, sal_Int32 n3 )
     return std::min(std::min(n1, n2), n3);
 }
 
+namespace {
+
 class IntArray2D
 {
 private:
@@ -127,6 +133,8 @@ public:
     sal_Int32 & Value( int i, int k  );
 };
 
+}
+
 IntArray2D::IntArray2D( int nDim1, int nDim2 )
 {
     n1 = nDim1;
diff --git a/linguistic/source/spelldsp.cxx b/linguistic/source/spelldsp.cxx
index ba0c45f08bc5..42ae281fd917 100644
--- a/linguistic/source/spelldsp.cxx
+++ b/linguistic/source/spelldsp.cxx
@@ -46,6 +46,7 @@ using namespace com::sun::star::uno;
 using namespace com::sun::star::linguistic2;
 using namespace linguistic;
 
+namespace {
 
 // ProposalList: list of proposals for misspelled words
 // The order of strings in the array should be left unchanged because the
@@ -73,6 +74,7 @@ public:
     std::vector< OUString > GetVector() const;
 };
 
+}
 
 bool ProposalList::HasEntry( const OUString &rText ) const
 {