[PD-dev] [leapmotion] 2.3.1 linking failure on Windows

[Christof Ressi]

Hey,

this can also happen when an auxiliary library cannot be found. You can 
check missing dependencies with the Dependencies program (modern 
successor to Dependency Walker): https://github.com/lucasg/Dependencies

Christof

On 05.01.2023 19:48, William Brent wrote:
> Hi again, I've got a successful build using cmake, but now I've run 
> into another issue. The external loads and works just fine in Pd on 
> the windows machine I compiled with, but fails on another machine with:
>
>     "leapmotion.dll: The specified module could not be found. (126)"
>
> I know this is the error thrown when the necessary .dll is missing (in 
> this case, Leap.dll), but I have Leap.dll in the same directory as my 
> leapmotion.dll binary. Both machines are running 64-bit Windows 10 
> using Pd 0.53-1 (amd64-32). Both have the 2.3.1 Leap Service software 
> installed. I've triple-checked everything I can think of...any ideas?
>
> On Tue, Jan 3, 2023 at 4:19 PM Christof Ressi <info at christofressi.com> 
> wrote:
>
>     To be more specific, the linker error itself is most likely caused
>     by name mangling differences. When you include the header file in
>     your project, the class/function definitions use /your /compiler's
>     name mangling, but the accompanying DLL has been built with
>     /another /compiler, using a different name mangling scheme.
>
>     Seems like there is also a C API:
>     https://docs.ultraleap.com/tracking-api/leapc-guide.html
>
>>     Things are of course different on windows: you generally cannot mix&match MSVC libraries with GCC binaries (and vice versa), at least if c++ is involved.
>     For the sake of completeness: yes, that's true for the typical
>     case, but there are techniques for creating binary compatible C++
>     interfaces. The most prominent one is COM. Other examples that
>     come to my mind are the VST3 SDK or openvr SDK.
>     On 03.01.2023 21:12, IOhannes m zmölnig wrote:
>>     Am 3. Jänner 2023 23:10:59 MEZ schrieb William Brent<william.brent at gmail.com>  <mailto:william.brent at gmail.com>:
>>>     x86_64-w64-mingw32/12.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe:
>>>     src/leapmotion.o:leapmotion.cpp:(.text+0x411): undefined reference to
>>>     `Leap::Frame::timestamp() const'
>>     C++ is a fantastic language.
>>     Unfortunately it is not really standardised on the binary level, which basically means that you might not be able to use c++ libraries compiled with one compiler/linker with binaries created by another compiler/linker.
>>
>>     Now, clang kind of guarantees binary compatibility with g++ binaries, which pretty much covers the Linux & macOS worlds.
>>     Things are of course different on windows: you generally cannot mix&match MSVC libraries with GCC binaries (and vice versa), at least if c++ is involved.
>>
>>     Proprietary SDKs often provide MSVC libraries.
>>
>>     So if possible, try to use a C-library instead of a C++-library on windows.
>>
>>
>>     mfg.sfg.jfd
>>     IOhannes
>>
>>
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>
> -- 
> William Brent
>
> “Great minds flock together”
> Conflations: conversational idiom for the 21st century
>
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