Avoid unhelpful -Wunused-variable

...at least from "g++ (GCC) 5.1.1 20150618 (Red Hat 5.1.1-4)" with
--disable-debug, when a namespace-scope const variable with a "complex"
initializer declared in an include file remains unused.

Avoid that warning via SAL_CONSTEXPR, which in turn requires large parts of
o3tl::is_typed_flags to be SAL_CONSTEXPR, which in turn requires a new
HAVE_CXX14_CONSTEXPR to allow assert in constexpr functions, which in turn
requires using -std=c++14 instead of -std=c++11 where available, which in turn
(a) requires to /not/ use -std=c++14 if it would run into a bug between Clang
and libstdc++ discussed at <https://llvm.org/bugs/show_bug.cgi?id=24115>
"llvm-nm fails to build with gcc 5.1's libstdc++" (and which hits us in
sfx2/source/control/thumbnailview.cxx), and (b) requires a new
HAVE_CXX14_SIZED_DEALLOCATION to work around GCC 5.1 -Werror=sized-deallocation
(where Clang >= 3.7 only supports C++14 sized deallocation when explictly
enabled via -fsized-deallocation, btw).

This effectively reverts ff6462e6307e6924dc6c8178043ae9032f4b4152 "avoid unused
variable warning:" again.

Change-Id: I424e3561452a3e6d8c8a9604d6c737cab49840c4
Reviewed-on: https://gerrit.libreoffice.org/18918
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Tested-by: Stephan Bergmann <sbergman@redhat.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/sal/cpprt/operators_new_delete.cxx b/sal/cpprt/operators_new_delete.cxx
index 064caa5946f5..5fbd9c09be7d 100644
--- a/sal/cpprt/operators_new_delete.cxx
+++ b/sal/cpprt/operators_new_delete.cxx
@@ -18,8 +18,11 @@
  */
 
 #include <algorithm>
+#include <cstddef>
 #include <new>
 #include <string.h>
+
+#include <config_global.h>
 #include <osl/diagnose.h>
 #include <rtl/alloc.h>
 
@@ -152,6 +155,20 @@ void SAL_CALL operator delete (void * p) throw ()
     deallocate (p, ScalarTraits());
 }
 
+#if HAVE_CXX14_SIZED_DEALLOCATION
+#if defined __clang__
+#pragma GCC diagnostic push // as happens on Mac OS X:
+#pragma GCC diagnostic ignored "-Wimplicit-exception-spec-mismatch"
+#endif
+void SAL_CALL operator delete (void * p, std::size_t) noexcept
+{
+    deallocate (p, ScalarTraits());
+}
+#if defined __clang__
+#pragma GCC diagnostic pop
+#endif
+#endif
+
 // T * p = new(nothrow) T; delete(nothrow) p;
 
 void* SAL_CALL operator new (std::size_t n, std::nothrow_t const &) throw ()
@@ -176,6 +193,20 @@ void SAL_CALL operator delete[] (void * p) throw ()
     deallocate (p, VectorTraits());
 }
 
+#if HAVE_CXX14_SIZED_DEALLOCATION
+#if defined __clang__
+#pragma GCC diagnostic push // as happens on Mac OS X:
+#pragma GCC diagnostic ignored "-Wimplicit-exception-spec-mismatch"
+#endif
+void SAL_CALL operator delete[] (void * p, std::size_t) noexcept
+{
+    deallocate (p, VectorTraits());
+}
+#if defined __clang__
+#pragma GCC diagnostic pop
+#endif
+#endif
+
 // T * p = new(nothrow) T[n]; delete(nothrow)[] p;
 
 void* SAL_CALL operator new[] (std::size_t n, std::nothrow_t const &) throw ()