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>

3 files changed, 50 insertions, 1 deletions

diff --git a/vcl/qa/cppunit/errorhandler.cxx b/vcl/qa/cppunit/errorhandler.cxx
index 2936234ceedf..21c672ac5ba6 100644
--- a/vcl/qa/cppunit/errorhandler.cxx
+++ b/vcl/qa/cppunit/errorhandler.cxx
@@ -12,9 +12,13 @@
 
 #include <vcl/errinf.hxx>
 
+class ErrorHandlerTest;
+
+namespace {
+
 class MockErrorHandler : private ErrorHandler
 {
-    friend class ErrorHandlerTest;
+    friend ErrorHandlerTest;
 
 protected:
     virtual bool CreateString(const ErrorInfo *pErrInfo, OUString &rErrString) const override
@@ -28,6 +32,7 @@ protected:
     }
 };
 
+}
 
 class ErrorHandlerTest : public test::BootstrapFixture
 {
diff --git a/vcl/qa/cppunit/lifecycle.cxx b/vcl/qa/cppunit/lifecycle.cxx
index 51d90776bb44..857ad9b46d08 100644
--- a/vcl/qa/cppunit/lifecycle.cxx
+++ b/vcl/qa/cppunit/lifecycle.cxx
@@ -143,6 +143,8 @@ void LifecycleTest::testParentedWidgets()
     testWidgets(xWin);
 }
 
+namespace {
+
 class DisposableChild : public vcl::Window
 {
 public:
@@ -153,6 +155,8 @@ public:
     }
 };
 
+}
+
 void LifecycleTest::testChildDispose()
 {
     VclPtrInstance<WorkWindow> xWin(nullptr, WB_APP|WB_STDWORK);
@@ -178,6 +182,8 @@ void LifecycleTest::testPostDispose()
     CPPUNIT_ASSERT(!xWin->GetWindow(GetWindowType::Parent));
 }
 
+namespace {
+
 class FocusCrashPostDispose : public TabControl
 {
 public:
@@ -203,6 +209,8 @@ public:
     }
 };
 
+}
+
 void LifecycleTest::testFocus()
 {
     ScopedVclPtrInstance<WorkWindow> xWin(nullptr, WB_APP|WB_STDWORK);
@@ -215,6 +223,8 @@ void LifecycleTest::testFocus()
     // CPPUNIT_ASSERT(xChild->HasFocus());
 }
 
+namespace {
+
 template <class vcl_type>
 class LeakTestClass : public vcl_type
 {
@@ -272,6 +282,8 @@ public:
     }
 };
 
+}
+
 void LifecycleTest::testLeakage()
 {
     std::vector<LeakTestObject *> aObjects;
diff --git a/vcl/qa/cppunit/timer.cxx b/vcl/qa/cppunit/timer.cxx
index 90705d26ec19..03f295943ea1 100644
--- a/vcl/qa/cppunit/timer.cxx
+++ b/vcl/qa/cppunit/timer.cxx
@@ -27,6 +27,8 @@
 // Enables timer tests that appear to provoke windows under load unduly.
 //#define TEST_TIMERPRECISION
 
+namespace {
+
 /// Avoid our timer tests just wedging the build if they fail.
 class WatchDog : public osl::Thread
 {
@@ -47,6 +49,8 @@ public:
     }
 };
 
+}
+
 static WatchDog * aWatchDog = new WatchDog( 120 ); // random high number in secs
 
 class TimerTest : public test::BootstrapFixture
@@ -102,6 +106,7 @@ void TimerTest::testWatchdog()
 }
 #endif
 
+namespace {
 
 class IdleBool : public Idle
 {
@@ -121,6 +126,8 @@ public:
     }
 };
 
+}
+
 void TimerTest::testIdle()
 {
     bool bTriggered = false;
@@ -147,6 +154,8 @@ void TimerTest::testIdleMainloop()
     CPPUNIT_ASSERT_MESSAGE("mainloop idle triggered", bTriggered);
 }
 
+namespace {
+
 class TimerBool : public Timer
 {
     bool &mrBool;
@@ -165,6 +174,8 @@ public:
     }
 };
 
+}
+
 void TimerTest::testDurations()
 {
     static const sal_uLong aDurations[] = { 0, 1, 500, 1000 };
@@ -180,6 +191,7 @@ void TimerTest::testDurations()
     }
 }
 
+namespace {
 
 class AutoTimerCount : public AutoTimer
 {
@@ -207,6 +219,8 @@ public:
     }
 };
 
+}
+
 #ifdef TEST_TIMERPRECISION
 
 void TimerTest::testAutoTimer()
@@ -321,6 +335,7 @@ void TimerTest::testAutoTimerStop()
     CPPUNIT_ASSERT( !Application::Reschedule() );
 }
 
+namespace {
 
 class YieldTimer : public Timer
 {
@@ -337,6 +352,8 @@ public:
     }
 };
 
+}
+
 void TimerTest::testNestedTimer()
 {
     sal_Int32 nCount = 0;
@@ -347,6 +364,7 @@ void TimerTest::testNestedTimer()
         Application::Yield();
 }
 
+namespace {
 
 class SlowCallbackTimer : public Timer
 {
@@ -366,6 +384,8 @@ public:
     }
 };
 
+}
+
 void TimerTest::testSlowTimerCallback()
 {
     bool bBeenSlow = false;
@@ -380,6 +400,7 @@ void TimerTest::testSlowTimerCallback()
         Application::Yield();
 }
 
+namespace {
 
 class TriggerIdleFromIdle : public Idle
 {
@@ -401,6 +422,8 @@ public:
     }
 };
 
+}
+
 void TimerTest::testTriggerIdleFromIdle()
 {
     bool bTriggered1 = false;
@@ -413,6 +436,7 @@ void TimerTest::testTriggerIdleFromIdle()
     CPPUNIT_ASSERT_MESSAGE("idle not triggered", bTriggered2);
 }
 
+namespace {
 
 class IdleInvokedReStart : public Idle
 {
@@ -431,6 +455,8 @@ public:
     }
 };
 
+}
+
 void TimerTest::testInvokedReStart()
 {
     sal_Int32 nCount = 0;
@@ -439,6 +465,7 @@ void TimerTest::testInvokedReStart()
     CPPUNIT_ASSERT_EQUAL( sal_Int32(2), nCount );
 }
 
+namespace {
 
 class IdleSerializer : public Idle
 {
@@ -461,6 +488,8 @@ public:
     }
 };
 
+}
+
 void TimerTest::testPriority()
 {
     // scope, so tasks are deleted
@@ -487,6 +516,7 @@ void TimerTest::testPriority()
     }
 }
 
+namespace {
 
 class TestAutoIdleRR : public AutoIdle
 {
@@ -506,6 +536,8 @@ public:
     }
 };
 
+}
+
 IMPL_LINK_NOARG(TestAutoIdleRR, IdleRRHdl, Timer *, void)
 {
     ++mrCount;