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>

31 files changed, 207 insertions, 11 deletions

diff --git a/sal/osl/all/utility.cxx b/sal/osl/all/utility.cxx
index 5f157c120b2d..76bdc4cd26ed 100644
--- a/sal/osl/all/utility.cxx
+++ b/sal/osl/all/utility.cxx
@@ -27,6 +27,8 @@
 namespace osl
 {
 
+namespace {
+
 class OGlobalTimer
 {
 
@@ -38,6 +40,8 @@ public:
 
 };
 
+}
+
 static OGlobalTimer aGlobalTimer;
 
 } // namespace osl
diff --git a/sal/osl/unx/conditn.cxx b/sal/osl/unx/conditn.cxx
index cede35a86d04..d73d67e91b37 100644
--- a/sal/osl/unx/conditn.cxx
+++ b/sal/osl/unx/conditn.cxx
@@ -29,6 +29,8 @@
 #include <osl/conditn.h>
 #include <osl/time.h>
 
+namespace {
+
 struct oslConditionImpl
 {
     pthread_cond_t  m_Condition;
@@ -36,6 +38,8 @@ struct oslConditionImpl
     bool            m_State;
 };
 
+}
+
 oslCondition SAL_CALL osl_createCondition()
 {
     oslConditionImpl* pCond;
diff --git a/sal/osl/unx/file.cxx b/sal/osl/unx/file.cxx
index b6a0acaae2c4..cfd71419d3fe 100644
--- a/sal/osl/unx/file.cxx
+++ b/sal/osl/unx/file.cxx
@@ -60,6 +60,8 @@
 #include <android/asset_manager.h>
 #endif
 
+namespace {
+
 struct FileHandle_Impl
 {
     pthread_mutex_t m_mutex;
@@ -155,6 +157,8 @@ struct FileHandle_Impl
     };
 };
 
+}
+
 FileHandle_Impl::Guard::Guard(pthread_mutex_t * pMutex)
     : m_mutex(pMutex)
 {
diff --git a/sal/osl/unx/file_path_helper.cxx b/sal/osl/unx/file_path_helper.cxx
index 4d629f849868..163deb0c2493 100644
--- a/sal/osl/unx/file_path_helper.cxx
+++ b/sal/osl/unx/file_path_helper.cxx
@@ -158,6 +158,8 @@ bool osl_systemPathIsLocalOrParentDirectoryEntry(
             dirent == "..");
 }
 
+namespace {
+
 /** Simple iterator for a path list separated by the specified character
 */
 class path_list_iterator
@@ -225,6 +227,8 @@ private:
     const sal_Unicode*  m_path_segment_end;
 };
 
+}
+
 bool osl_searchPath(
     const rtl_uString* pustrFilePath,
     const rtl_uString* pustrSearchPathList,
diff --git a/sal/osl/unx/process.cxx b/sal/osl/unx/process.cxx
index 41d6de0b04ea..d479e0d40cfc 100644
--- a/sal/osl/unx/process.cxx
+++ b/sal/osl/unx/process.cxx
@@ -788,6 +788,8 @@ void SAL_CALL osl_freeProcessHandle(oslProcess Process)
 }
 
 #if defined(LINUX)
+namespace {
+
 struct osl_procStat
 {
    /* from 'stat' */
@@ -848,6 +850,8 @@ struct osl_procStat
     unsigned long vm_lib;     /* library size */
 };
 
+}
+
 static bool osl_getProcStat(pid_t pid, struct osl_procStat* procstat)
 {
     int fd = 0;
diff --git a/sal/osl/unx/process_impl.cxx b/sal/osl/unx/process_impl.cxx
index 35a5b90ece0d..fe7dc9db5ccf 100644
--- a/sal/osl/unx/process_impl.cxx
+++ b/sal/osl/unx/process_impl.cxx
@@ -140,6 +140,8 @@ oslProcessError bootstrap_getExecutableFile(rtl_uString ** ppFileURL)
 
 #endif
 
+namespace {
+
 struct CommandArgs_Impl
 {
     pthread_mutex_t m_mutex;
@@ -147,6 +149,8 @@ struct CommandArgs_Impl
     rtl_uString **  m_ppArgs;
 };
 
+}
+
 static struct CommandArgs_Impl g_command_args =
 {
     PTHREAD_MUTEX_INITIALIZER,
@@ -409,12 +413,16 @@ oslProcessError SAL_CALL osl_getProcessWorkingDir(rtl_uString **ppustrWorkingDir
     return result;
 }
 
+namespace {
+
 struct ProcessLocale_Impl
 {
     pthread_mutex_t m_mutex;
     rtl_Locale *    m_pLocale;
 };
 
+}
+
 static struct ProcessLocale_Impl g_process_locale =
 {
     PTHREAD_MUTEX_INITIALIZER,
diff --git a/sal/osl/unx/profile.cxx b/sal/osl/unx/profile.cxx
index ad8868b5490c..717316c0817c 100644
--- a/sal/osl/unx/profile.cxx
+++ b/sal/osl/unx/profile.cxx
@@ -58,8 +58,6 @@ enum osl_TLockMode
     un_lock, read_lock, write_lock
 };
 
-}
-
 struct osl_TFile
 {
     int     m_Handle;
@@ -104,6 +102,8 @@ struct osl_TProfileImpl
     bool        m_bIsValid;
 };
 
+}
+
 static osl_TFile* openFileImpl(const sal_Char* pszFilename, oslProfileOption ProfileFlags);
 static osl_TStamp closeFileImpl(osl_TFile* pFile, oslProfileOption Flags);
 static bool   OslProfile_lockFile(const osl_TFile* pFile, osl_TLockMode eMode);
diff --git a/sal/osl/unx/thread.cxx b/sal/osl/unx/thread.cxx
index 5ea77495daa6..fb694ebd92cd 100644
--- a/sal/osl/unx/thread.cxx
+++ b/sal/osl/unx/thread.cxx
@@ -75,6 +75,8 @@
 #define THREADIMPL_FLAGS_ATTACHED   0x00010
 #define THREADIMPL_FLAGS_DESTROYED  0x00020
 
+namespace {
+
 typedef struct osl_thread_impl_st
 {
     pthread_t           m_hThread;
@@ -95,18 +97,26 @@ struct osl_thread_priority_st
     int m_Lowest;
 };
 
+}
+
 #define OSL_THREAD_PRIORITY_INITIALIZER { 127, 96, 64, 32, 0 }
 static void osl_thread_priority_init_Impl();
 
+namespace {
+
 struct osl_thread_textencoding_st
 {
     pthread_key_t    m_key;     /* key to store thread local text encoding */
     rtl_TextEncoding m_default; /* the default text encoding */
 };
 
+}
+
 #define OSL_THREAD_TEXTENCODING_INITIALIZER { 0, RTL_TEXTENCODING_DONTKNOW }
 static void osl_thread_textencoding_init_Impl();
 
+namespace {
+
 struct osl_thread_global_st
 {
     pthread_once_t                    m_once;
@@ -114,6 +124,8 @@ struct osl_thread_global_st
     struct osl_thread_textencoding_st m_textencoding;
 };
 
+}
+
 static struct osl_thread_global_st g_thread =
 {
     PTHREAD_ONCE_INIT,
@@ -555,6 +567,8 @@ void SAL_CALL osl_setThreadName(char const * name)
 
 /* osl_getThreadIdentifier @@@ see TODO @@@ */
 
+namespace {
+
 struct HashEntry
 {
     pthread_t            Handle;
@@ -562,6 +576,8 @@ struct HashEntry
     HashEntry *          Next;
 };
 
+}
+
 static HashEntry* HashTable[31];
 static const int HashSize = SAL_N_ELEMENTS(HashTable);
 
@@ -951,12 +967,16 @@ oslThreadPriority SAL_CALL osl_getThreadPriority(const oslThread Thread)
     return Priority;
 }
 
+namespace {
+
 struct wrapper_pthread_key
 {
     pthread_key_t m_key;
     oslThreadKeyCallbackFunction pfnCallback;
 };
 
+}
+
 oslThreadKey SAL_CALL osl_createThreadKey( oslThreadKeyCallbackFunction pCallback )
 {
     wrapper_pthread_key *pKey = static_cast<wrapper_pthread_key*>(malloc(sizeof(wrapper_pthread_key)));
diff --git a/sal/qa/osl/condition/osl_Condition.cxx b/sal/qa/osl/condition/osl_Condition.cxx
index 0d3cba799583..0e6a56f37c3b 100644
--- a/sal/qa/osl/condition/osl_Condition.cxx
+++ b/sal/qa/osl/condition/osl_Condition.cxx
@@ -31,8 +31,6 @@ enum ConditionType
     thread_type_wait
 };
 
-}
-
 /** thread for testing Condition.
  */
 class ConditionThread : public Thread
@@ -61,6 +59,8 @@ protected:
     }
 };
 
+}
+
 namespace osl_Condition
 {
     /** testing the method:
diff --git a/sal/qa/osl/file/osl_File.cxx b/sal/qa/osl/file/osl_File.cxx
index 54c0e01b90ff..3811ab29d3e8 100644
--- a/sal/qa/osl/file/osl_File.cxx
+++ b/sal/qa/osl/file/osl_File.cxx
@@ -4997,6 +4997,8 @@ namespace osl_Directory
         }
     }
 
+    namespace {
+
     class DirCreatedObserver : public DirectoryCreationObserver
     {
     public:
@@ -5009,6 +5011,8 @@ namespace osl_Directory
         int i;
     };
 
+    }
+
     class createPath : public CppUnit::TestFixture
     {
     public:
@@ -5149,6 +5153,8 @@ OUString getCurrentPID()
     return OUString::number(nPID);
 }
 
+namespace {
+
 //~ do some clean up work after all test completed.
 class GlobalObject
 {
@@ -5197,6 +5203,8 @@ public:
     }
 };
 
+}
+
 static GlobalObject theGlobalObject;
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/sal/qa/osl/module/osl_Module.cxx b/sal/qa/osl/module/osl_Module.cxx
index 52112cb9f151..f440a715162f 100644
--- a/sal/qa/osl/module/osl_Module.cxx
+++ b/sal/qa/osl/module/osl_Module.cxx
@@ -44,6 +44,7 @@ static OUString getDllURL()
 
 namespace osl_Module
 {
+    namespace {
 
     /** class and member function that is available for module test :
     */
@@ -57,6 +58,8 @@ namespace osl_Module
         };
     };
 
+    }
+
     /** testing the methods:
         Module();
         Module( const OUString& strModuleName, sal_Int32 nRtldMode = SAL_LOADMODULE_DEFAULT);
diff --git a/sal/qa/osl/mutex/osl_Mutex.cxx b/sal/qa/osl/mutex/osl_Mutex.cxx
index d0b8283c68e3..c345ae33eb2b 100644
--- a/sal/qa/osl/mutex/osl_Mutex.cxx
+++ b/sal/qa/osl/mutex/osl_Mutex.cxx
@@ -49,6 +49,8 @@ namespace ThreadHelper
 
 // Beginning of the test cases for osl_Mutex class
 
+namespace {
+
 /** mutually exclusive data
 */
 struct resource {
@@ -229,6 +231,8 @@ protected:
     }
 };
 
+}
+
 namespace osl_Mutex
 {
 
@@ -524,6 +528,8 @@ CPPUNIT_TEST_SUITE_NAMED_REGISTRATION(osl_Mutex::getGlobalMutex, "osl_Mutex");
 
 // Beginning of the test cases for osl_Guard class
 
+namespace {
+
 class GuardThread : public Thread
 {
 public:
@@ -545,6 +551,8 @@ protected:
     }
 };
 
+}
+
 namespace osl_Guard
 {
     class ctor : public CppUnit::TestFixture
@@ -607,6 +615,8 @@ CPPUNIT_TEST_SUITE_NAMED_REGISTRATION(osl_Guard::ctor, "osl_Guard");
 
 // Beginning of the test cases for osl_ClearableGuard class
 
+namespace {
+
 /** Thread for test ClearableGuard
  */
 class ClearGuardThread : public Thread
@@ -635,6 +645,8 @@ protected:
     }
 };
 
+}
+
 namespace osl_ClearableGuard
 {
 
@@ -748,6 +760,8 @@ CPPUNIT_TEST_SUITE_NAMED_REGISTRATION( osl_ClearableGuard::clear, "osl_Clearable
 
 // Beginning of the test cases for osl_ResettableGuard class
 
+namespace {
+
 /** Thread for test ResettableGuard
  */
 class ResetGuardThread : public Thread
@@ -774,6 +788,8 @@ protected:
     }
 };
 
+}
+
 namespace osl_ResettableGuard
 {
     class ctor : public CppUnit::TestFixture
diff --git a/sal/qa/osl/pipe/osl_Pipe.cxx b/sal/qa/osl/pipe/osl_Pipe.cxx
index 482ae750f36f..d7bedb5baaa8 100644
--- a/sal/qa/osl/pipe/osl_Pipe.cxx
+++ b/sal/qa/osl/pipe/osl_Pipe.cxx
@@ -744,6 +744,8 @@ namespace osl_StreamPipe
     }
     // test read/write & send/recv data to pipe
 
+    namespace {
+
     class Pipe_DataSink_Thread : public Thread
     {
     public:
@@ -838,6 +840,8 @@ namespace osl_StreamPipe
             }
     };
 
+    }
+
     /** testing the method: read/write/send/recv and Pipe::accept
      */
     class recv : public CppUnit::TestFixture
diff --git a/sal/qa/osl/process/osl_Thread.cxx b/sal/qa/osl/process/osl_Thread.cxx
index 0b97d0b95d8c..3c9891b76e54 100644
--- a/sal/qa/osl/process/osl_Thread.cxx
+++ b/sal/qa/osl/process/osl_Thread.cxx
@@ -48,6 +48,8 @@
 
 using namespace osl;
 
+namespace {
+
 // Small stopwatch
 class StopWatch {
     TimeValue t1,t2;                                // Start and stoptime
@@ -69,6 +71,8 @@ public:
     double getTenthSec() const;
 };
 
+}
+
 // ================================= Stop Watch =================================
 
 // A small stopwatch for internal use
@@ -145,6 +149,8 @@ double StopWatch::getTenthSec() const
     return nValue ;
 }
 
+namespace {
+
 template <class T>
 class ThreadSafeValue
 {
@@ -168,6 +174,8 @@ public:
     void release() {m_aMutex.release();}
 };
 
+}
+
 namespace ThreadHelper
 {
     static void thread_sleep_tenth_sec(sal_Int32 _nTenthSec)
@@ -205,6 +213,8 @@ namespace ThreadHelper
     }
 }
 
+namespace {
+
 /** Simple thread for testing Thread-create.
 
     Just add 1 of value 0, and after running, result is 1.
@@ -393,6 +403,8 @@ public:
 
 };
 
+}
+
 namespace osl_Thread
 {
 
@@ -1671,6 +1683,8 @@ static void destroyCallback(void * data)
 
 static ThreadData myThreadData(destroyCallback);
 
+namespace {
+
 class myKeyThread : public Thread
 {
 public:
@@ -1708,8 +1722,12 @@ public:
         }
 };
 
+}
+
 static ThreadData idData;
 
+namespace {
+
 class idThread: public Thread
 {
 public:
@@ -1735,6 +1753,8 @@ public:
         }
 };
 
+}
+
 namespace osl_ThreadData
 {
 
diff --git a/sal/qa/osl/process/osl_process.cxx b/sal/qa/osl/process/osl_process.cxx
index eaf34bd46d5b..104f9238eea6 100644
--- a/sal/qa/osl/process/osl_process.cxx
+++ b/sal/qa/osl/process/osl_process.cxx
@@ -80,6 +80,8 @@ static OUString getExecutablePath()
 
 #if !defined _WIN32
 
+namespace {
+
 class exclude
 {
 public:
@@ -118,8 +120,6 @@ private:
     std::vector<OString> exclude_list_;
 };
 
-namespace
-{
     void tidy_container(std::vector<OString> &env_container)
     {
         //sort them because there are no guarantees to ordering
diff --git a/sal/qa/osl/security/osl_Security.cxx b/sal/qa/osl/security/osl_Security.cxx
index 3bce893731cc..bc00d27a21e7 100644
--- a/sal/qa/osl/security/osl_Security.cxx
+++ b/sal/qa/osl/security/osl_Security.cxx
@@ -309,6 +309,8 @@ CPPUNIT_TEST_SUITE_REGISTRATION(osl_Security::loginUserOnFileServer);
     */
 #include <cppunit/plugin/TestPlugInDefaultImpl.h>
 
+namespace {
+
 class MyTestPlugInImpl: public CPPUNIT_NS::TestPlugInDefaultImpl
 {
     public:
@@ -317,6 +319,8 @@ class MyTestPlugInImpl: public CPPUNIT_NS::TestPlugInDefaultImpl
                    const CPPUNIT_NS::PlugInParameters &parameters ) override;
 };
 
+}
+
 void MyTestPlugInImpl::initialize( CPPUNIT_NS::TestFactoryRegistry *,
                    const CPPUNIT_NS::PlugInParameters & )
 {
diff --git a/sal/qa/rtl/doublelock/rtl_doublelocking.cxx b/sal/qa/rtl/doublelock/rtl_doublelocking.cxx
index d2e094d19c12..6f59e55e62cd 100644
--- a/sal/qa/rtl/doublelock/rtl_doublelocking.cxx
+++ b/sal/qa/rtl/doublelock/rtl_doublelocking.cxx
@@ -50,7 +50,6 @@ struct Gregorian : public rtl::StaticWithInit<OUString, Gregorian> {
         return CONST_TEST_STRING;
     }
 };
-}
 
 /** Simple thread for testing Thread-create.
  * Just add 1 of value 0, and after running, result is 1.
@@ -108,6 +107,8 @@ public:
         }
 };
 
+}
+
 namespace rtl_DoubleLocking
 {
 
diff --git a/sal/qa/rtl/random/rtl_random.cxx b/sal/qa/rtl/random/rtl_random.cxx
index 1e0eb625d5f5..c43638277c90 100644
--- a/sal/qa/rtl/random/rtl_random.cxx
+++ b/sal/qa/rtl/random/rtl_random.cxx
@@ -139,6 +139,8 @@ public:
     CPPUNIT_TEST_SUITE_END();
 }; // class addBytes
 
+namespace {
+
 class Statistics
 {
     int m_nDispensation[256];
@@ -208,6 +210,8 @@ public:
 
 };
 
+}
+
 class getBytes : public CppUnit::TestFixture
 {
 public:
diff --git a/sal/qa/rtl/ref/rtl_ref.cxx b/sal/qa/rtl/ref/rtl_ref.cxx
index 2c7d3aae5276..2bf7c9803f3d 100644
--- a/sal/qa/rtl/ref/rtl_ref.cxx
+++ b/sal/qa/rtl/ref/rtl_ref.cxx
@@ -16,6 +16,8 @@
 namespace rtl_ref
 {
 
+namespace {
+
 class MoveTestClass
 {
 private:
@@ -45,6 +47,8 @@ public:
     void set_inc_flag() { m_bIncFlag = true; }
 };
 
+}
+
 static rtl::Reference< MoveTestClass > get_reference( MoveTestClass* pcTestClass )
 {
     // constructor will increment the reference count
diff --git a/sal/rtl/alloc_arena.cxx b/sal/rtl/alloc_arena.cxx
index 626d05c7b895..f126efdabd27 100644
--- a/sal/rtl/alloc_arena.cxx
+++ b/sal/rtl/alloc_arena.cxx
@@ -29,6 +29,8 @@
 #include <string.h>
 #include <stdio.h>
 
+namespace {
+
 /**
     @internal
 */
@@ -38,6 +40,8 @@ struct rtl_arena_list_st
     rtl_arena_type       m_arena_head;
 };
 
+}
+
 static rtl_arena_list_st g_arena_list;
 
 /**
diff --git a/sal/rtl/bootstrap.cxx b/sal/rtl/bootstrap.cxx
index 7f5d4317636a..dae54a88df66 100644
--- a/sal/rtl/bootstrap.cxx
+++ b/sal/rtl/bootstrap.cxx
@@ -55,11 +55,11 @@
 using osl::DirectoryItem;
 using osl::FileStatus;
 
-struct Bootstrap_Impl;
-
 namespace
 {
 
+struct Bootstrap_Impl;
+
 static char const VND_SUN_STAR_PATHNAME[] = "vnd.sun.star.pathname:";
 
 bool isPathnameUrl(OUString const & url)
@@ -111,8 +111,6 @@ OUString recursivelyExpandMacros(
     return expandMacros(file, text, mode, &link);
 }
 
-} // end namespace
-
 struct rtl_bootstrap_NameValue
 {
     OUString sName;
@@ -126,6 +124,8 @@ struct rtl_bootstrap_NameValue
         {}
 };
 
+} // end namespace
+
 typedef std::vector<rtl_bootstrap_NameValue> NameValueVector;
 
 static bool find(
@@ -281,6 +281,8 @@ static void EnsureNoFinalSlash (OUString & url)
         url = url.copy(0, i - 1);
 }
 
+namespace {
+
 struct Bootstrap_Impl
 {
     sal_Int32 _nRefCount;
@@ -313,6 +315,8 @@ struct Bootstrap_Impl
         ExpandRequestLink const * requestStack) const;
 };
 
+}
+
 Bootstrap_Impl::Bootstrap_Impl( OUString const & rIniName )
     : _nRefCount( 0 ),
       _base_ini( nullptr ),
diff --git a/sal/rtl/cipher.cxx b/sal/rtl/cipher.cxx
index 26d9cca29afc..9bc438114651 100644
--- a/sal/rtl/cipher.cxx
+++ b/sal/rtl/cipher.cxx
@@ -105,6 +105,8 @@ typedef rtlCipherError(cipher_update_t) (
 
 typedef void (cipher_delete_t) (rtlCipher Cipher);
 
+namespace {
+
 struct Cipher_Impl
 {
     rtlCipherAlgorithm  m_algorithm;
@@ -117,6 +119,8 @@ struct Cipher_Impl
     cipher_delete_t    *m_delete;
 };
 
+}
+
 rtlCipher SAL_CALL rtl_cipher_create(
     rtlCipherAlgorithm Algorithm,
     rtlCipherMode      Mode) SAL_THROW_EXTERN_C()
@@ -192,6 +196,8 @@ void SAL_CALL rtl_cipher_destroy(rtlCipher Cipher) SAL_THROW_EXTERN_C()
         pImpl->m_delete(Cipher);
 }
 
+namespace {
+
 #if !defined LIBO_CIPHER_OPENSSL_BACKEND
 #define CIPHER_ROUNDS_BF 16
 
@@ -223,6 +229,8 @@ struct CipherBF_Impl
     CipherContextBF m_context;
 };
 
+}
+
 #if !defined LIBO_CIPHER_OPENSSL_BACKEND
 static rtlCipherError BF_init(
     CipherContextBF *ctx,
@@ -1150,6 +1158,8 @@ void SAL_CALL rtl_cipher_destroyBF(rtlCipher Cipher) SAL_THROW_EXTERN_C()
 #define CIPHER_CBLOCK_ARCFOUR 256
 #endif
 
+namespace {
+
 struct ContextARCFOUR_Impl
 {
 #if defined LIBO_CIPHER_OPENSSL_BACKEND
@@ -1166,6 +1176,8 @@ struct CipherARCFOUR_Impl
     ContextARCFOUR_Impl m_context;
 };
 
+}
+
 static rtlCipherError rtl_cipherARCFOUR_update_Impl(
     ContextARCFOUR_Impl *ctx,
     const sal_uInt8     *pData,   sal_Size nDatLen,
diff --git a/sal/rtl/digest.cxx b/sal/rtl/digest.cxx
index 1000fc0aed02..55af5ad7c3b2 100644
--- a/sal/rtl/digest.cxx
+++ b/sal/rtl/digest.cxx
@@ -52,6 +52,8 @@ typedef rtlDigestError (Digest_update_t) (
 typedef rtlDigestError (Digest_get_t) (
     void *ctx, sal_uInt8 *Buffer, sal_uInt32 BufLen);
 
+namespace {
+
 struct Digest_Impl
 {
     rtlDigestAlgorithm  m_algorithm;
@@ -63,6 +65,8 @@ struct Digest_Impl
     Digest_get_t       *m_get;
 };
 
+}
+
 static void swapLong(sal_uInt32 *pData, sal_uInt32 nDatLen)
 {
     sal_uInt32 *X;
@@ -175,6 +179,8 @@ void SAL_CALL rtl_digest_destroy(rtlDigest Digest) SAL_THROW_EXTERN_C()
 #define DIGEST_CBLOCK_MD2 16
 #define DIGEST_LBLOCK_MD2 16
 
+namespace {
+
 struct DigestContextMD2
 {
     sal_uInt32 m_nDatLen;
@@ -189,6 +195,8 @@ struct DigestMD2_Impl
     DigestContextMD2 m_context;
 };
 
+}
+
 static void initMD2   (DigestContextMD2 *ctx);
 static void updateMD2 (DigestContextMD2 *ctx);
 static void endMD2    (DigestContextMD2 *ctx);
@@ -437,6 +445,8 @@ void SAL_CALL rtl_digest_destroyMD2(rtlDigest Digest) SAL_THROW_EXTERN_C()
 #define DIGEST_CBLOCK_MD5 64
 #define DIGEST_LBLOCK_MD5 16
 
+namespace {
+
 struct DigestContextMD5
 {
     sal_uInt32 m_nDatLen;
@@ -451,6 +461,8 @@ struct DigestMD5_Impl
     DigestContextMD5 m_context;
 };
 
+}
+
 static void initMD5 (DigestContextMD5 *ctx);
 static void updateMD5 (DigestContextMD5 *ctx);
 static void endMD5 (DigestContextMD5 *ctx);
@@ -824,6 +836,8 @@ typedef sal_uInt32 DigestSHA_update_t(sal_uInt32 x);
 static sal_uInt32 updateSHA_0(sal_uInt32 x);
 static sal_uInt32 updateSHA_1(sal_uInt32 x);
 
+namespace {
+
 struct DigestContextSHA
 {
     DigestSHA_update_t *m_update;
@@ -839,6 +853,8 @@ struct DigestSHA_Impl
     DigestContextSHA m_context;
 };
 
+}
+
 static void initSHA(
     DigestContextSHA *ctx, DigestSHA_update_t *fct);
 
@@ -1390,6 +1406,8 @@ void SAL_CALL rtl_digest_destroySHA1(rtlDigest Digest) SAL_THROW_EXTERN_C()
 
 #define DIGEST_CBLOCK_HMAC_MD5 64
 
+namespace {
+
 struct ContextHMAC_MD5
 {
     DigestMD5_Impl m_hash;
@@ -1402,6 +1420,8 @@ struct DigestHMAC_MD5_Impl
     ContextHMAC_MD5 m_context;
 };
 
+}
+
 static void initHMAC_MD5(ContextHMAC_MD5 * ctx);
 static void ipadHMAC_MD5(ContextHMAC_MD5 * ctx);
 static void opadHMAC_MD5(ContextHMAC_MD5 * ctx);
@@ -1586,6 +1606,8 @@ void SAL_CALL rtl_digest_destroyHMAC_MD5(rtlDigest Digest) SAL_THROW_EXTERN_C()
 
 #define DIGEST_CBLOCK_HMAC_SHA1 64
 
+namespace {
+
 struct ContextHMAC_SHA1
 {
     DigestSHA_Impl m_hash;
@@ -1598,6 +1620,8 @@ struct DigestHMAC_SHA1_Impl
     ContextHMAC_SHA1 m_context;
 };
 
+}
+
 static void initHMAC_SHA1(ContextHMAC_SHA1 * ctx);
 static void ipadHMAC_SHA1(ContextHMAC_SHA1 * ctx);
 static void opadHMAC_SHA1(ContextHMAC_SHA1 * ctx);
diff --git a/sal/rtl/hash.cxx b/sal/rtl/hash.cxx
index 4cbe1da785c6..4fed60889f50 100644
--- a/sal/rtl/hash.cxx
+++ b/sal/rtl/hash.cxx
@@ -26,12 +26,16 @@
 #include <osl/diagnose.h>
 #include <sal/macros.h>
 
+namespace {
+
 struct StringHashTableImpl {
     sal_uInt32    nEntries;
     sal_uInt32    nSize;
     rtl_uString **pData;
 };
 
+}
+
 typedef StringHashTableImpl StringHashTable;
 
 // Only for use in the implementation
diff --git a/sal/rtl/locale.cxx b/sal/rtl/locale.cxx
index e362a342bcbc..bae0f40b3d66 100644
--- a/sal/rtl/locale.cxx
+++ b/sal/rtl/locale.cxx
@@ -26,6 +26,8 @@
 #include <memory>
 #include <unordered_map>
 
+namespace {
+
 struct locale_deleter
 {
     void operator() (rtl_Locale* p) noexcept
@@ -37,6 +39,8 @@ struct locale_deleter
     }
 };
 
+}
+
 using locale_unique_ptr = std::unique_ptr<rtl_Locale, locale_deleter>;
 
 static std::unordered_map<sal_Int32, locale_unique_ptr>* g_pLocaleTable = nullptr;
diff --git a/sal/rtl/random.cxx b/sal/rtl/random.cxx
index c9cc0f841ea9..418358b22e22 100644
--- a/sal/rtl/random.cxx
+++ b/sal/rtl/random.cxx
@@ -46,6 +46,8 @@
     if ((z) < 0) (z) += 30307; \
 }
 
+namespace {
+
 struct RandomData_Impl
 {
     sal_Int16 m_nX;
@@ -53,12 +55,16 @@ struct RandomData_Impl
     sal_Int16 m_nZ;
 };
 
+}
+
 static double data (RandomData_Impl *pImpl);
 
 #define RTL_RANDOM_DIGEST      rtl_Digest_AlgorithmMD5
 #define RTL_RANDOM_SIZE_DIGEST RTL_DIGEST_LENGTH_MD5
 #define RTL_RANDOM_SIZE_POOL   1023
 
+namespace {
+
 struct RandomPool_Impl
 {
     rtlDigest  m_hDigest;
@@ -69,6 +75,8 @@ struct RandomPool_Impl
     sal_uInt32 m_nCount;
 };
 
+}
+
 static bool initPool(RandomPool_Impl *pImpl);
 
 static void seedPool(
diff --git a/sal/rtl/uuid.cxx b/sal/rtl/uuid.cxx
index bb9490ef8b99..130be12456d6 100644
--- a/sal/rtl/uuid.cxx
+++ b/sal/rtl/uuid.cxx
@@ -55,6 +55,8 @@
                      ( (  static_cast<sal_uInt32>(p[3])) & 0xff);\
                }
 
+namespace {
+
 struct UUID
 {
       sal_uInt32          time_low;
@@ -65,6 +67,8 @@ struct UUID
       sal_uInt8           node[6];
 };
 
+}
+
 static void write_v3( sal_uInt8 *pUuid  )
 {
     UUID uuid;
diff --git a/sal/textenc/convertisciidevangari.cxx b/sal/textenc/convertisciidevangari.cxx
index b8566ed6a51e..ae25d811df2d 100644
--- a/sal/textenc/convertisciidevangari.cxx
+++ b/sal/textenc/convertisciidevangari.cxx
@@ -22,6 +22,8 @@
 using namespace sal::detail::textenc;
 using namespace rtl::textenc;
 
+namespace {
+
 struct IsciiDevanagariToUnicode
 {
     sal_uInt8 m_cPrevChar;
@@ -57,6 +59,8 @@ struct UnicodeToIsciiDevanagari
         sal_uInt32 * pInfo, sal_Size * pSrcCvtChars);
 };
 
+}
+
 static const sal_Unicode IsciiDevanagariMap[256] =
 {
     0x0000,0x0001,0x0002,0x0003,0x0004,0x0005,0x0006,0x0007,
diff --git a/sal/textenc/tcvtutf7.cxx b/sal/textenc/tcvtutf7.cxx
index b09ccd47f1d8..1a1ca7603241 100644
--- a/sal/textenc/tcvtutf7.cxx
+++ b/sal/textenc/tcvtutf7.cxx
@@ -91,6 +91,8 @@ static unsigned char const aImplMustShiftTab[128] =
 
 /* ----------------------------------------------------------------------- */
 
+namespace {
+
 struct ImplUTF7ToUCContextData
 {
     bool                    mbShifted;
@@ -100,6 +102,8 @@ struct ImplUTF7ToUCContextData
     sal_uInt32              mnBufferBits;
 };
 
+}
+
 /* ----------------------------------------------------------------------- */
 
 void* ImplUTF7CreateUTF7TextToUnicodeContext()
@@ -410,6 +414,8 @@ sal_Size ImplUTF7ToUnicode( SAL_UNUSED_PARAMETER const void*, void* pContext,
 
 /* ======================================================================= */
 
+namespace {
+
 struct ImplUTF7FromUCContextData
 {
     bool                    mbShifted;
@@ -417,6 +423,8 @@ struct ImplUTF7FromUCContextData
     sal_uInt32              mnBufferBits;
 };
 
+}
+
 /* ----------------------------------------------------------------------- */
 
 void* ImplUTF7CreateUnicodeToTextContext()
diff --git a/sal/textenc/tcvtutf8.cxx b/sal/textenc/tcvtutf8.cxx
index 950d810e8b85..ca29156c418f 100644
--- a/sal/textenc/tcvtutf8.cxx
+++ b/sal/textenc/tcvtutf8.cxx
@@ -30,6 +30,8 @@
 #include "tenchelp.hxx"
 #include "unichars.hxx"
 
+namespace {
+
 struct ImplUtf8ToUnicodeContext
 {
     sal_uInt32 nUtf32;
@@ -43,6 +45,8 @@ struct ImplUnicodeToUtf8Context
     sal_Unicode nHighSurrogate; /* 0xFFFF: write BOM */
 };
 
+}
+
 void * ImplCreateUtf8ToUnicodeContext()
 {
     ImplUtf8ToUnicodeContext * p = new ImplUtf8ToUnicodeContext;
diff --git a/sal/textenc/tencinfo.cxx b/sal/textenc/tencinfo.cxx
index f541fcb20004..b69cf4c586fd 100644
--- a/sal/textenc/tencinfo.cxx
+++ b/sal/textenc/tencinfo.cxx
@@ -102,6 +102,8 @@ static bool Impl_matchString( const char* pCompStr, const char* pMatchStr )
 
 /* ======================================================================= */
 
+namespace {
+
 struct ImplStrCharsetDef
 {
     const char*             mpCharsetStr;
@@ -114,6 +116,8 @@ struct ImplStrFirstPartCharsetDef
     const ImplStrCharsetDef*    mpSecondPartTab;
 };
 
+}
+
 /* ======================================================================= */
 
 sal_Bool SAL_CALL rtl_getTextEncodingInfo( rtl_TextEncoding eTextEncoding, rtl_TextEncodingInfo* pEncInfo )