gcc Error: wrong number of template arguments (1, should be 3)

[0xBADEAFFE]

out_value_policy.hpp:199:33: error: wrong number of template arguments (1, should be 3)
    storage_.template construct<T>();
out_value_policy.hpp:220:33: error: wrong number of template arguments (1, should be 3)
    storage_.template construct<T>();

[decimad]

Hello, can you please provide a testcase or some sample code for me to look at?

[neomantra]

I'm getting this on Ubuntu 16.04 with gcc 5.4.0, latest master:

cmake -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LUABIND=ON .
make

[ 79%] Building CXX object test/CMakeFiles/test_policies.dir/test_policies.cpp.o
In file included from /home/pc/evan/projects/luabind-deboostified/test/test_policies.cpp:26:0:
/home/pc/evan/projects/luabind-deboostified/luabind/out_value_policy.hpp: In member function ‘T& luabind::detail::pure_out_value_converter<Size, Policies>::to_cpp(lua_State*, luabind::detail::by_reference<T>, int)’:
/home/pc/evan/projects/luabind-deboostified/luabind/out_value_policy.hpp:200:34: error: wrong number of template arguments (1, should be 3)
     storage_.template construct<T>();
                                  ^
In file included from /home/pc/evan/projects/luabind-deboostified/luabind/class.hpp:83:0,
                 from /home/pc/evan/projects/luabind-deboostified/luabind/luabind.hpp:28,
                 from /home/pc/evan/projects/luabind-deboostified/test/test_policies.cpp:25:
/home/pc/evan/projects/luabind-deboostified/luabind/detail/constructor.hpp:51:10: note: provided for ‘template<class T, class Pointer, class Signature> struct luabind::detail::construct’
   struct construct :
          ^
In file included from /home/pc/evan/projects/luabind-deboostified/test/test_policies.cpp:26:0:
/home/pc/evan/projects/luabind-deboostified/luabind/out_value_policy.hpp: In member function ‘T* luabind::detail::pure_out_value_converter<Size, Policies>::to_cpp(lua_State*, luabind::detail::by_pointer<T>, int)’:
/home/pc/evan/projects/luabind-deboostified/luabind/out_value_policy.hpp:221:34: error: wrong number of template arguments (1, should be 3)
     storage_.template construct<T>();
                                  ^
In file included from /home/pc/evan/projects/luabind-deboostified/luabind/class.hpp:83:0,
                 from /home/pc/evan/projects/luabind-deboostified/luabind/luabind.hpp:28,
                 from /home/pc/evan/projects/luabind-deboostified/test/test_policies.cpp:25:
/home/pc/evan/projects/luabind-deboostified/luabind/detail/constructor.hpp:51:10: note: provided for ‘template<class T, class Pointer, class Signature> struct luabind::detail::construct’
   struct construct :
          ^
test/CMakeFiles/test_policies.dir/build.make:62: recipe for target 'test/CMakeFiles/test_policies.dir/test_policies.cpp.o' failed
make[2]: *** [test/CMakeFiles/test_policies.dir/test_policies.cpp.o] Error 1
CMakeFiles/Makefile2:2458: recipe for target 'test/CMakeFiles/test_policies.dir/all' failed
make[1]: *** [test/CMakeFiles/test_policies.dir/all] Error 2
Makefile:138: recipe for target 'all' failed
make: *** [all] Error 2

[neomantra]

The Dockerfile below reproduces it on current master. Save it as Dockerfile.ubuntu and build it like so:

cd luabind-deboostified
docker build -f Dockerfile.ubuntu .

# Dockerfile.ubuntu
FROM ubuntu:16.04

RUN DEBIAN_FRONTEND=noninteractive apt-get update -y \
    && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
        ca-certificates \
        cmake \ 
        g++ \
        gcc \
        git \
        lua5.1-dev \
        make

RUN cd /tmp \
    && git clone https://github.com/decimad/luabind-deboostified.git

VOLUME  /tmp/luabind-deboostified

RUN cd /tmp/luabind-deboostified \
    && cmake -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Release -DLUABIND_BUILD_SHARED=ON . \
    && make

[decimad]

Hello, thank you for the feedback, I will see what I can do shortly.

[neomantra]

I did further exploration last night.... using ubuntu:16.10 and gcc-6 elicits the same compiler error. But, compiling on ubuntu:16.10 and clang works (with a minor fix I had to do which I'll make a PR for later today). I also tried C++14 standard with the same results.

I don't get why gcc is trying to use luabind::detail::construct instead of out_value_detail::temporary_storage_size<Size>::construct

[neomantra]

So as I was saying... if I rename out_value_detail::temporary_storage_size<Size>::construct to construct2 and invoke that in lines 200 and 221, then it compiles fine.

I don't think there is a proper test for this (because commenting out the line entirely still passes the test), but it is compiling.

[decimad]

Man, I don't understand this problem. It smells like a compiler bug really?

[decimad]

Oh and out_value_converter is missing the dependant template keywords as well...

[decimad]

I commited a preliminary fix as suggested on https://www.c-plusplus.net/forum/343641 that works without renaming.

All this line does is default-constructing an object in the already reserved memory. A pointer to this will be passed to the function as the "out"-tagged parameter, which will get overwritten right away. Since an "int" holds no invariants that could be broken, that copy operation cannot fail. That's why the test still passes if you comment out that line, it could potentially break for non-trivial types though.

[Wohlstand]

I'll try to build that at me

[Wohlstand]

Okay, you also forgot to apply fix at 221'th line where I did fix myself, but another issue has been found:

impicit_cast test fails

./test_implicit_cast
/home/wohlstand/_git_repos/luabind-deboostified/test/test_implicit_cast.cpp:59"TEST_CHECK failed: "false""

But okay:

// This test fails because shared_ptr-converter is broken.
    DOSTRING_EXPECTED(L,
        "a = A()\n"
        "no_convert(a)",
        ("No matching overload found, candidates:\n"
        "void no_convert(custom ["
        + std::string(typeid(std::shared_ptr<A>).name()) + "])").c_str());

I'll post this as another issue (if someone wasn't posted it yet)

[decimad]

Arrrr, I need to catch some sleep... Btw.: This problem is/was actually a bug in gcc and clang.

[decimad]

Okay, I think I can consider this fixed now, right?