[cfe-dev] problem with std::function and virtual destructor

[Rich E]

Hi all,

Can anyone explain why the following doesn't compile?

#include <functional>

struct X{
typedef std::function<void(X&)> callback_type;
virtual ~X() {}
private:
callback_type _cb;
};

int main(){}


If you comment out the virtual destructor, the code compiles fine.  Full
error report:


################################################

CompileC
build/test_function_callback.build/Debug/test_function_callback.build/Objects-normal/x86_64/main.o
test_function_callback/main.cpp normal x86_64 c++
com.apple.compilers.llvm.clang.1_0.compiler

    cd /Volumes/ssd/code/sandbox/test_function_callback

    setenv LANG en_US.US-ASCII


/Applications/Xcode45-DP2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang
-x c++ -arch x86_64 -fmessage-length=0 -std=gnu++11 -stdlib=libc++
-Wno-trigraphs -fpascal-strings -O0 -Wno-missing-field-initializers
-Wno-missing-prototypes -Wreturn-type -Wno-non-virtual-dtor
-Wno-overloaded-virtual -Wno-exit-time-destructors -Wformat
-Wno-missing-braces -Wparentheses -Wswitch -Wno-unused-function
-Wno-unused-label -Wno-unused-parameter -Wunused-variable -Wunused-value
-Wuninitialized -Wno-unknown-pragmas -Wno-shadow -Wno-four-char-constants
-Wno-conversion -Wno-sign-compare -Wshorten-64-to-32 -Wno-newline-eof
-Wc++11-extensions -DDEBUG=1 -isysroot
/Applications/Xcode45-DP2.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk
-fasm-blocks -Wdeprecated-declarations -Winvalid-offsetof
-mmacosx-version-min=10.7 -g -fvisibility-inlines-hidden
-Wno-sign-conversion -iquote
/Volumes/ssd/code/sandbox/test_function_callback/build/test_function_callback.build/Debug/test_function_callback.build/test_function_callback-generated-files.hmap
-I/Volumes/ssd/code/sandbox/test_function_callback/build/test_function_callback.build/Debug/test_function_callback.build/test_function_callback-own-target-headers.hmap
-I/Volumes/ssd/code/sandbox/test_function_callback/build/test_function_callback.build/Debug/test_function_callback.build/test_function_callback-all-target-headers.hmap
-iquote
/Volumes/ssd/code/sandbox/test_function_callback/build/test_function_callback.build/Debug/test_function_callback.build/test_function_callback-project-headers.hmap
-I/Volumes/ssd/code/sandbox/test_function_callback/build/Debug/include
-I/Applications/Xcode45-DP2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
-I/Volumes/ssd/code/sandbox/test_function_callback/build/test_function_callback.build/Debug/test_function_callback.build/DerivedSources/x86_64
-I/Volumes/ssd/code/sandbox/test_function_callback/build/test_function_callback.build/Debug/test_function_callback.build/DerivedSources
-F/Volumes/ssd/code/sandbox/test_function_callback/build/Debug -MMD -MT
dependencies -MF
/Volumes/ssd/code/sandbox/test_function_callback/build/test_function_callback.build/Debug/test_function_callback.build/Objects-normal/x86_64/main.d
--serialize-diagnostics
/Volumes/ssd/code/sandbox/test_function_callback/build/test_function_callback.build/Debug/test_function_callback.build/Objects-normal/x86_64/main.dia
-c
/Volumes/ssd/code/sandbox/test_function_callback/test_function_callback/main.cpp
-o
/Volumes/ssd/code/sandbox/test_function_callback/build/test_function_callback.build/Debug/test_function_callback.build/Objects-normal/x86_64/main.o


In file included from
/Volumes/ssd/code/sandbox/test_function_callback/test_function_callback/main.cpp:1:

In file included from
/Applications/Xcode45-DP2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/functional:462:

/Applications/Xcode45-DP2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/type_traits:2825:19:
error: invalid application of 'sizeof' to an incomplete type 'X'

    static_assert(sizeof(_Tp) > 0, "Type must be complete.");

                  ^~~~~~~~~~~

/Applications/Xcode45-DP2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/type_traits:2830:15:
note: in instantiation of template class 'std::__1::__check_complete<X>'
requested here

    : private __check_complete<_Tp>

              ^

/Applications/Xcode45-DP2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/type_traits:2812:15:
note: in instantiation of template class 'std::__1::__check_complete<X &>'
requested here

      private __check_complete<_T0, _Tp...>

              ^

/Applications/Xcode45-DP2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/type_traits:2978:15:
note: in instantiation of template class
'std::__1::__check_complete<std::__1::function<void (X &)> &, X &>'
requested here

    : private __check_complete<_Fp, _Args...>

              ^

/Applications/Xcode45-DP2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/type_traits:2989:11:
note: in instantiation of template class
'std::__1::__invokable_imp<std::__1::function<void (X &)> &, X &>'
requested here

          __invokable_imp<_Fp, _Args...>::value>

          ^

/Applications/Xcode45-DP2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/functional:1115:33:
note: in instantiation of template class
'std::__1::__invokable<std::__1::function<void (X &)> &, X &>' requested
here

    template <class _Fp, bool = __invokable<_Fp&, _ArgTypes...>::value>

                                ^

/Applications/Xcode45-DP2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/functional:1163:9:
note: in instantiation of default argument for
'__callable<std::__1::function<void (X &)> >' required here

        __callable<typename decay<_Fp>::type>::value,

        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

/Applications/Xcode45-DP2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/functional:1166:7:
note: while substituting deduced template arguments into function template
'operator=' [with _Fp = const std::__1::function<void (X &)> &]

      operator=(_Fp&&);

      ^

/Volumes/ssd/code/sandbox/test_function_callback/test_function_callback/main.cpp:3:8:
note: definition of 'X' is not complete until the closing '}'

struct X{

       ^

1 error generated.
################################################



Please let me know if I should report this as a bug.

Cheers,
Rich
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