Invalid C++ code being generated

[Misiur]

Again, really sorry for not being able to reproduce minimal viable case - I can't isolate just the failing code without library I'm using. The code compiles fine on haxe 3.2, and returns weird errors for 3.4. (not haxe ones, but C++ - should this be reported in hxcpp instead?)

https://github.com/Misiur/haxe34crasher - requires "ecx" library.

Compiling group: haxe

cl.exe -Iinclude -nologo /WX- /fp:precise -DHX_WINDOWS -D_USING_V140_SDK71_ -GR -O2(optim-std) -Zi(debug) -FdD:\Dev\private\haxe\crasher\export\bin\obj/msvc19xp/vc.pdb(debug) -Od(debug) -O2(release) -Os(optim-size) -FS -Oy- -c -EHs -GS- -arch:SSE -ID:/Programs/Haxe/haxe/lib/hxcpp/3,4,49/include -DHXCPP_VISIT_ALLOCS(haxe) -DHXCPP_API_LEVEL=331(haxe) -D_CRT_SECURE_NO_DEPRECATE -D_ALLOW_MSC_VER_MISMATCH -D_ALLOW_ITERATOR_DEBUG_LEVEL_MISMATCH -wd4996 ... tags=[haxe,static]

 - src/Foobar.cpp 

Error: Foobar.cpp
./src/Foobar.cpp(82): error C2672: 'cpp::Pointer_obj::fromRaw': no matching overloaded function found
./src/Foobar.cpp(82): error C2784: 'cpp::Pointer<T> cpp::Pointer_obj::fromRaw(const T *)': could not deduce template argument for 'const T *' from 'cpp::RawAutoCast'
D:/Programs/Haxe/haxe/lib/hxcpp/3,4,49/include\cpp/Pointer.h(527): note: see declaration of 'cpp::Pointer_obj::fromRaw'
./src/Foobar.cpp(82): error C2784: 'cpp::Pointer<T> cpp::Pointer_obj::fromRaw(T *)': could not deduce template argument for 'T *' from 'cpp::RawAutoCast'
D:/Programs/Haxe/haxe/lib/hxcpp/3,4,49/include\cpp/Pointer.h(525): note: see declaration of 'cpp::Pointer_obj::fromRaw'
./src/Foobar.cpp(82): error C2227: left of '->get_value' must point to class/struct/union/generic type
Error: Build failed

[nadako]

@hughsando that was pretty easy to reduce:

class Main {
    static function main() {
        cpp.Pointer.fromRaw(cpp.Pointer.addressOf(null).rawCast());
    }
}

generates

HXLINE(   3)		::cpp::Pointer_obj::fromRaw(::cpp::Pointer_obj::addressOf(null())->rawCast());

which fails with

./src/Main.cpp(29): error C2672: 'cpp::Pointer_obj::fromRaw': no matching overloaded function found
./src/Main.cpp(29): error C2784: 'cpp::Pointer<T> cpp::Pointer_obj::fromRaw(const T *)': could not deduce template argument for 'const T *' from 'cpp::RawAutoCast'
d:/code/haxe/lib/hxcpp/git/include\cpp/Pointer.h(527): note: see declaration of 'cpp::Pointer_obj::fromRaw'
./src/Main.cpp(29): error C2784: 'cpp::Pointer<T> cpp::Pointer_obj::fromRaw(T *)': could not deduce template argument for 'T *' from 'cpp::RawAutoCast'
d:/code/haxe/lib/hxcpp/git/include\cpp/Pointer.h(525): note: see declaration of 'cpp::Pointer_obj::fromRaw'

[hughsando]

I think this should be a compile-time error, since addressOf requires a reference - which 'null' is not. Logically, once you have the address of null, you should be able to set to to something else - which is not going to work. Coding this in the compiler is tricky because a lot of the use for this comes from externs, and you can't really trust the external types as described. I could explicitly check for the 'null' constant passed to reference - but I suspect there will be other cases too.

…

On Sat, Feb 4, 2017 at 9:14 AM, Dan Korostelev ***@***.***> wrote: @hughsando <https://github.com/hughsando> that was pretty easy to reduce: class Main { static function main() { cpp.Pointer.fromRaw(cpp.Pointer.addressOf(null).rawCast()); } } generates HXLINE( 3) ::cpp::Pointer_obj::fromRaw(::cpp::Pointer_obj::addressOf(null())->rawCast()); which fails with ./src/Main.cpp(29): error C2672: 'cpp::Pointer_obj::fromRaw': no matching overloaded function found ./src/Main.cpp(29): error C2784: 'cpp::Pointer<T> cpp::Pointer_obj::fromRaw(const T *)': could not deduce template argument for 'const T *' from 'cpp::RawAutoCast' d:/code/haxe/lib/hxcpp/git/include\cpp/Pointer.h(527): note: see declaration of 'cpp::Pointer_obj::fromRaw' ./src/Main.cpp(29): error C2784: 'cpp::Pointer<T> cpp::Pointer_obj::fromRaw(T *)': could not deduce template argument for 'T *' from 'cpp::RawAutoCast' d:/code/haxe/lib/hxcpp/git/include\cpp/Pointer.h(525): note: see declaration of 'cpp::Pointer_obj::fromRaw' — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#5994 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABlp1hQNy-zr_giW--R3tTdmdE5dheuaks5rY9D3gaJpZM4L1yw2> .

[nadako]

Hmm, it wasn't null there in the original code, I just added it for a minimal example.

[Misiur]

Sorry for not getting back sooner. I updated to git version of hxcpp, and now I get more weird results. First with the exact same repo I linked in first post:

Error: Foobar.cpp
./src/Foobar.cpp(82): error C2440: 'type cast': cannot convert from 'void' to 'Foo'
./src/Foobar.cpp(82): note: Expressions of type void cannot be converted to other types

Generated code in Foobar.cpp

HXLINE(  91)		 ::ecx::Service tmp = _hx___world->_services->__get((int)1).StaticCast<  ::ecx::Service >();
HXLINE( 108)		this->_foo = ( ( ::Foo)(::cpp::Pointer_obj::fromRaw(::cpp::Pointer_obj::addressOf(tmp)->rawCast())->get_value()) );

I tried to isolate the problem as @nadako did, but I'm not certain if it's equivalent as the error is a little different this time:

class Foo 
{
    public function new() {}

    public var bar = 15;
}

class Main
{
    static function main()
    {
        var tmp = new Foo();
        var foo = cpp.Pointer.fromRaw(cpp.Pointer.addressOf(tmp).rawCast()).get_value();
        trace(foo);
    }
}

Error while compiling

Error: Main.cpp
./src/Main.cpp(33): error C2440: 'initializing': cannot convert from 'void' to 'Dynamic &'
./src/Main.cpp(33): note: Expressions of type void cannot be converted to other types

CPP code generated:

HXLINE(  12)		 ::Foo tmp =  ::Foo_obj::__alloc( HX_CTX );
HXLINE(  13)		 ::Dynamic & foo = ::cpp::Pointer_obj::fromRaw(::cpp::Pointer_obj::addressOf(tmp)->rawCast())->get_value();
HXLINE(  14)		::haxe::Log_obj::trace(foo,hx::SourceInfo(HX_("Main.hx",05,5c,7e,08),14,HX_("Main",59,64,2f,33),HX_("main",39,38,56,48)));

Thank you

[hughsando]

The problem here is that the "rawCast" converts the pointer to a "void *", and there is nothing then to tell hxcpp what the type should be, ie that it should be a Foo *. The when you go back fromRaw and get a value, you end up with a void. To work around this, you can add explicit casts, or assign to a typed variable

class Test
{
    static function main()
    {
        var tmp = new Foo();
        var foo:cpp.Pointer<Foo> = cpp.Pointer.fromRaw(cpp.Pointer.addressOf(tmp).rawCast());
        trace(foo.value);
    }
}

[eliasku]

@hughsando Thanks for snippet!