codemaker/source/cppumaker/cpputype.cxx | 12 ++++++++++--
include/unotools/weakref.hxx | 7 ++++++-
2 files changed, 16 insertions(+), 3 deletions(-)
New commits:
commit 485c9d4f0e59e13e772da8f8a7975f0ddd77c33e
Author: Stephan Bergmann <sberg...@redhat.com>
AuthorDate: Fri Dec 2 17:01:02 2022 +0100
Commit: Stephan Bergmann <sberg...@redhat.com>
CommitDate: Sat Dec 3 07:09:38 2022 +0000
Clarify the use of untools::WeakReference
...which had been introduced in 78040af9acea0ab681aa54ff23844b647bc9b4f3
"loplugin:refcounting in sc" as a variation on css::uno::WeakReference from
include/cppuhelper/weakref.hxx, but without giving much of a rationale.
And, at least for --with-latest-c++ builds using a capable C++20 compiler,
ensure that the given interface_type is such that the static_cast and
dynamic_cast in the implementation of unotools::WeakReference::get are
actually
sound: If interface_type could be a UNO interface type, that would imply
that
the xInterface obtained from the underlying WeakReferenceHelper::get()
could be
a proxy from the C++ UNO bridge, which could (a) be a proxy for only a
subtype
of interface_type (e.g., just for XInterface), so that the static_cast
would be
broken, and (b) be a proxy for which the vtable's RTTI slot is not set up
(see
e.g. the ENABLE_RUNTIME_OPTIMIZATIONS code in
bridges::cpp_uno::shared::VtableFactory::initializeBlock in
bridges/source/cpp_uno/gcc3_linux_x86-64/cpp2uno.cxx), so that the
dynamic_cast
could crash. (These issues can even happen when the given interface_type
is a
C++ implementation class type, but the given object has been bridged over
some
C++ to C++ UNO ("purpose") bridge, but lets leave it at that...)
This required adding some cppu::detail::isUnoInterfaceType predicate to the
include files generated by cppumaker, which can be useful in other places
too.
(For the call to isUnoInterfaceType in the requires-clause of
unotools::WeakReference<interface_type>::get to give the correct answer, it
is
important that interface_type is a complete type---i.e., the corresponding
codemaker-generated .hpp having been included if interface_type actually
were a
UNO include type. But that is already nicely required by the call to
std::is_convertible_v in the implementation of that function, anyway.)
Change-Id: Ia5efd70085d2d6d45fa0995d00dc8def564bbe5f
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/143601
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sberg...@redhat.com>
diff --git a/codemaker/source/cppumaker/cpputype.cxx
b/codemaker/source/cppumaker/cpputype.cxx
index 03fcd033beca..2c8f938e6bb1 100644
--- a/codemaker/source/cppumaker/cpputype.cxx
+++ b/codemaker/source/cppumaker/cpputype.cxx
@@ -1184,7 +1184,7 @@ void InterfaceType::dumpHppFile(
out << "\n";
addDefaultHxxIncludes(includes);
includes.dump(out, &name_, !(m_cppuTypeLeak || m_cppuTypeDynamic));
- out << "\n";
+ out << "\n#if defined LIBO_INTERNAL_ONLY\n#include
<type_traits>\n#endif\n\n";
dumpGetCppuType(out);
out << "\n::css::uno::Type const & "
<< codemaker::cpp::scopedCppName(u2b(name_))
@@ -1194,7 +1194,15 @@ void InterfaceType::dumpHppFile(
dumpType(out, name_, false, false, true);
out << " >::get();\n";
dec();
- out << "}\n\n#endif // "<< headerDefine << "\n";
+ out << "}\n\n#if defined LIBO_INTERNAL_ONLY\nnamespace cppu::detail {\n";
+ if (name_ == "com.sun.star.uno.XInterface") {
+ out << "template<typename> struct IsUnoInterfaceType:
::std::false_type {};\n"
+ "template<typename T> inline constexpr auto isUnoInterfaceType
="
+ " IsUnoInterfaceType<T>::value;\n";
+ }
+ out << "template<> struct IsUnoInterfaceType<";
+ dumpType(out, name_, false, false, true);
+ out << ">: ::std::true_type {};\n}\n#endif\n\n#endif // "<< headerDefine
<< "\n";
}
void InterfaceType::dumpAttributes(FileStream & out) const
diff --git a/include/unotools/weakref.hxx b/include/unotools/weakref.hxx
index 554bd433b687..1d9b29f82e70 100644
--- a/include/unotools/weakref.hxx
+++ b/include/unotools/weakref.hxx
@@ -42,7 +42,9 @@ namespace unotools
behind it *is* thread-safe, so multiple threads can have their own
WeakReferences to the same XWeak object.
- @tparam interface_type type of interface
+ @tparam interface_type Must be a C++ implementation class type, not a UNO
interface type. (See
+ the C++20 requires-clause on the get member. That clause is not put on
the class as a whole to
+ avoid overly tight requirements on when interface_type needs to be
complete.)
*/
template <class interface_type>
class SAL_WARN_UNUSED WeakReference : public
com::sun::star::uno::WeakReferenceHelper
@@ -113,6 +115,9 @@ public:
@return hard reference or null, if the weakly referenced interface
has gone
*/
rtl::Reference<interface_type> SAL_CALL get() const
+#if __cplusplus >= 202002L
+ requires(!cppu::detail::isUnoInterfaceType<interface_type>)
+#endif
{
css::uno::Reference<css::uno::XInterface> xInterface =
WeakReferenceHelper::get();
// If XInterface is an ambiguous base of interface_type, we have to
use dynamic_cast,
