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>

6 files changed, 45 insertions, 4 deletions

diff --git a/vcl/workben/icontest.cxx b/vcl/workben/icontest.cxx
index 28bcee6c85b7..4203ecdaf9d3 100644
--- a/vcl/workben/icontest.cxx
+++ b/vcl/workben/icontest.cxx
@@ -57,8 +57,6 @@ namespace {
             static_cast<double>(aValue.Nanosec) / (1000*1000*1000);
     }
 
-}
-
 class MyWorkWindow : public WorkWindow
 {
     double mnStartTime;
@@ -78,6 +76,8 @@ public:
     virtual void Resize() override;
 };
 
+}
+
 MyWorkWindow::MyWorkWindow( vcl::Window* pParent, WinBits nWinStyle )
     : WorkWindow(pParent, nWinStyle)
     , mpBitmap(nullptr)
@@ -133,6 +133,8 @@ void MyWorkWindow::Resize()
     SAL_INFO("vcl.icontest", "Resize " << GetSizePixel());
 }
 
+namespace {
+
 class IconTestApp : public Application
 {
 public:
@@ -147,6 +149,8 @@ private:
     void DoItWithVcl(const OUString& sImageFile);
 };
 
+}
+
 void IconTestApp::Init()
 {
     nRet = EXIT_SUCCESS;
diff --git a/vcl/workben/mtfdemo.cxx b/vcl/workben/mtfdemo.cxx
index 0ee726e051f8..ea987186ceb2 100644
--- a/vcl/workben/mtfdemo.cxx
+++ b/vcl/workben/mtfdemo.cxx
@@ -32,6 +32,8 @@
 
 using namespace css;
 
+namespace {
+
 class DemoMtfWin : public WorkWindow
 {
     GDIMetaFile maMtf;
@@ -55,6 +57,8 @@ public:
     virtual void Paint(vcl::RenderContext& rRenderContext, const tools::Rectangle& rRect)  override;
 };
 
+}
+
 void DemoMtfWin::Paint(vcl::RenderContext& rRenderContext, const tools::Rectangle& rRect)
 {
     maMtf.Play(this, maMtf.GetActionSize());
@@ -62,6 +66,8 @@ void DemoMtfWin::Paint(vcl::RenderContext& rRenderContext, const tools::Rectangl
     WorkWindow::Paint(rRenderContext, rRect);
 }
 
+namespace {
+
 class DemoMtfApp : public Application
 {
     VclPtr<DemoMtfWin> mpWin;
@@ -149,6 +155,7 @@ private:
 
 };
 
+}
 
 void vclmain::createApplication()
 {
diff --git a/vcl/workben/svdem.cxx b/vcl/workben/svdem.cxx
index ebd7c94fb289..399a3683f853 100644
--- a/vcl/workben/svdem.cxx
+++ b/vcl/workben/svdem.cxx
@@ -71,12 +71,16 @@ SAL_IMPLEMENT_MAIN()
     return 0;
 }
 
+namespace {
+
 class MyWin : public WorkWindow
 {
 public:
                 MyWin( vcl::Window* pParent, WinBits nWinStyle );
 };
 
+}
+
 void Main()
 {
     ScopedVclPtrInstance< MyWin > aMainWin( nullptr, WB_APP | WB_STDWORK );
diff --git a/vcl/workben/svpclient.cxx b/vcl/workben/svpclient.cxx
index 2396c6fa69f2..5d7cf8b9aae8 100644
--- a/vcl/workben/svpclient.cxx
+++ b/vcl/workben/svpclient.cxx
@@ -91,6 +91,8 @@ SAL_IMPLEMENT_MAIN()
     return 0;
 }
 
+namespace {
+
 class MyWin : public WorkWindow
 {
     VclPtr<PushButton>   m_aListButton;
@@ -112,6 +114,8 @@ public:
     DECL_STATIC_LINK( MyWin, QuitHdl, Button*, void );
 };
 
+}
+
 void Main()
 {
     ScopedVclPtrInstance< MyWin > aMainWin( nullptr, WB_STDWORK );
diff --git a/vcl/workben/svptest.cxx b/vcl/workben/svptest.cxx
index 72ff179821a8..06937d2255ed 100644
--- a/vcl/workben/svptest.cxx
+++ b/vcl/workben/svptest.cxx
@@ -82,6 +82,8 @@ SAL_IMPLEMENT_MAIN()
     return 0;
 }
 
+namespace {
+
 class MyWin : public WorkWindow
 {
     Bitmap      m_aBitmap;
@@ -91,6 +93,8 @@ public:
     virtual void Paint( vcl::RenderContext& /*rRenderContext*/, const tools::Rectangle& rRect ) override;
 };
 
+}
+
 void Main()
 {
     ScopedVclPtrInstance< MyWin > aMainWin( nullptr, WB_APP | WB_STDWORK );
diff --git a/vcl/workben/vcldemo.cxx b/vcl/workben/vcldemo.cxx
index 42e4c5cda164..b1657c965d28 100644
--- a/vcl/workben/vcldemo.cxx
+++ b/vcl/workben/vcldemo.cxx
@@ -93,8 +93,6 @@ enum RenderStyle {
     RENDER_EXPANDED, // expanded view of this renderer
 };
 
-}
-
 class DemoRenderer
 {
     Bitmap   maIntroBW;
@@ -1527,6 +1525,8 @@ public:
     }
 };
 
+}
+
 #if FIXME_BOUNCE_BUTTON
 IMPL_LINK_NOARG(DemoRenderer,BounceTimerCb,Timer*,void)
 {
@@ -1715,6 +1715,8 @@ int DemoRenderer::selectNextRenderer()
     return mnSelectedRenderer;
 }
 
+namespace {
+
 class DemoWin : public WorkWindow
 {
     DemoRenderer &mrRenderer;
@@ -1830,6 +1832,9 @@ struct PointerData {
     PointerStyle eStyle;
     const char * name;
 };
+
+}
+
 static const PointerData gvPointerData [] = {
     { PointerStyle::Null, "Null" },
     { PointerStyle::Magnify, "Magnify" },
@@ -1895,6 +1900,9 @@ static const PointerData gvPointerData [] = {
     { PointerStyle::HideWhitespace, "HideWhitespace" },
     { PointerStyle::ShowWhitespace, "ShowWhitespace" },
 };
+
+namespace {
+
 class DemoWidgets : public WorkWindow
 {
     VclPtr<MenuBar> mpBar;
@@ -2027,6 +2035,8 @@ public:
     }
 };
 
+}
+
 IMPL_LINK_NOARG(DemoWidgets, GLTestClick, Button*, void)
 {
     sal_Int32 nSelected = mpGLCombo->GetSelectedEntryPos();
@@ -2069,6 +2079,8 @@ IMPL_LINK(DemoWidgets, CursorButtonClick, Button*, pButton, void)
     assert(false);
 }
 
+namespace {
+
 class DemoPopup : public FloatingWindow
 {
  public:
@@ -2113,6 +2125,8 @@ class DemoPopup : public FloatingWindow
     }
 };
 
+}
+
 class OpenGLTests
 {
     VclPtr<WorkWindow> mxWinA;
@@ -2280,6 +2294,8 @@ include/vcl/outdev.hxx:                                              DrawTextFla
     }
 };
 
+namespace {
+
 class DemoApp : public Application
 {
     static int showHelp(DemoRenderer &rRenderer)
@@ -2418,6 +2434,8 @@ protected:
     }
 };
 
+}
+
 void vclmain::createApplication()
 {
 #ifdef _WIN32