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, 34 insertions, 0 deletions

diff --git a/sc/qa/extras/scddelinkobj.cxx b/sc/qa/extras/scddelinkobj.cxx
index 49a8fda8c244..a64104e661f1 100644
--- a/sc/qa/extras/scddelinkobj.cxx
+++ b/sc/qa/extras/scddelinkobj.cxx
@@ -45,6 +45,8 @@ static utl::TempFile createTempCopy(OUString const& url)
     return tmp;
 }
 
+namespace
+{
 struct TempFileBase
 {
     utl::TempFile m_TempFile;
@@ -53,6 +55,7 @@ struct TempFileBase
     {
     }
 };
+}
 
 class ScDDELinkObj : public CalcUnoApiTest,
                      public TempFileBase,
diff --git a/sc/qa/extras/scuniquecellformatsenumeration.cxx b/sc/qa/extras/scuniquecellformatsenumeration.cxx
index c0a8f9cdf8fa..ea6a76e7680d 100644
--- a/sc/qa/extras/scuniquecellformatsenumeration.cxx
+++ b/sc/qa/extras/scuniquecellformatsenumeration.cxx
@@ -30,6 +30,8 @@ using namespace css::uno;
 
 namespace sc_apitest
 {
+namespace
+{
 struct RGBColor
 {
     int m_nRed;
@@ -45,6 +47,7 @@ struct RGBColor
 
     sal_Int32 hashCode() const { return (255 << 24) | (m_nRed << 16) | (m_nGreen << 8) | m_nBlue; }
 };
+}
 
 class ScUniqueCellFormatsEnumeration : public CalcUnoApiTest, public apitest::XEnumeration
 {
diff --git a/sc/qa/unit/mark_test.cxx b/sc/qa/unit/mark_test.cxx
index f6c2e81ef356..6c2d3e870370 100644
--- a/sc/qa/unit/mark_test.cxx
+++ b/sc/qa/unit/mark_test.cxx
@@ -16,10 +16,20 @@
 #include <markdata.hxx>
 #include "../../source/core/data/markarr.cxx"
 #include "../../source/core/data/markmulti.cxx"
+#if defined __GNUC__ && !defined __clang__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wsubobject-linkage"
+    // automatically suppressed in the main .cxx, but not in this included one
+#endif
 #include "../../source/core/data/segmenttree.cxx"
+#if defined __GNUC__ && !defined __clang__
+#pragma GCC diagnostic push
+#endif
 
 #include <utility>
 
+namespace {
+
 struct MarkTestData  // To represent a single rectangle part of a multiselection
 {
     ScRange aRange;
@@ -80,6 +90,8 @@ struct MultiMarkTestData
     std::vector<std::pair<SCCOL,SCCOL>> aColsWithUnequalMarksList;
 };
 
+}
+
 class Test : public CppUnit::TestFixture
 {
 public:
diff --git a/sc/qa/unit/subsequent_filters-test.cxx b/sc/qa/unit/subsequent_filters-test.cxx
index 9110505667fc..e3c7bfae4d82 100644
--- a/sc/qa/unit/subsequent_filters-test.cxx
+++ b/sc/qa/unit/subsequent_filters-test.cxx
@@ -1015,6 +1015,8 @@ void ScFiltersTest::testBorderODS()
     xDocSh->DoClose();
 }
 
+namespace {
+
 struct Border
 {
     sal_Int16 column;
@@ -1049,6 +1051,8 @@ struct Border
     lStyle(static_cast<SvxBorderLineStyle>(lSt)), tStyle(static_cast<SvxBorderLineStyle>(tSt)), rStyle(static_cast<SvxBorderLineStyle>(rSt)), bStyle(static_cast<SvxBorderLineStyle>(bSt)) {};
 };
 
+}
+
 void ScFiltersTest::testBordersOoo33()
 {
     std::vector<Border> borders;
diff --git a/sc/qa/unit/ucalc.cxx b/sc/qa/unit/ucalc.cxx
index ae28aadeae31..5f5e79cb7933 100644
--- a/sc/qa/unit/ucalc.cxx
+++ b/sc/qa/unit/ucalc.cxx
@@ -1677,6 +1677,8 @@ static void checkMatrixElements(const ScMatrix& rMat)
     }
 }
 
+namespace {
+
 struct AllZeroMatrix
 {
     void operator() (SCSIZE /*nCol*/, SCSIZE /*nRow*/, const ScMatrixValue& rVal) const
@@ -1743,6 +1745,8 @@ struct PartiallyFilledEmptyMatrix
     }
 };
 
+}
+
 void Test::testMatrix()
 {
     svl::SharedStringPool& rPool = m_pDoc->GetSharedStringPool();
diff --git a/sc/qa/unit/ucalc_formula.cxx b/sc/qa/unit/ucalc_formula.cxx
index 6bbe59d067ea..a8a98ce2fa44 100644
--- a/sc/qa/unit/ucalc_formula.cxx
+++ b/sc/qa/unit/ucalc_formula.cxx
@@ -5437,11 +5437,15 @@ void Test::testFuncVLOOKUP()
     m_pDoc->DeleteTab(0);
 }
 
+namespace {
+
 struct StrStrCheck {
     const char* pVal;
     const char* pRes;
 };
 
+}
+
 template<size_t DataSize, size_t FormulaSize, int Type>
 static void runTestMATCH(ScDocument* pDoc, const char* aData[DataSize], const StrStrCheck aChecks[FormulaSize])
 {
diff --git a/sc/qa/unit/ucalc_sharedformula.cxx b/sc/qa/unit/ucalc_sharedformula.cxx
index 7cb85e8c9bbf..b67880171d63 100644
--- a/sc/qa/unit/ucalc_sharedformula.cxx
+++ b/sc/qa/unit/ucalc_sharedformula.cxx
@@ -599,6 +599,8 @@ void Test::testSharedFormulasRefUpdateRange()
     m_pDoc->DeleteTab(0);
 }
 
+namespace {
+
 struct SortByArea
 {
     bool operator ()( const sc::AreaListener& rLeft, const sc::AreaListener& rRight ) const
@@ -622,6 +624,8 @@ struct SortByArea
     }
 };
 
+}
+
 void Test::testSharedFormulasRefUpdateRangeDeleteRow()
 {
     sc::AutoCalcSwitch aACSwitch(*m_pDoc, true); // turn on auto calc.