Mixing static library with dynamic

[aharondavid]

When i do the following I got an error:

1. emmake make create a static module - someModule.a
2. a.wasm linked with -s SIDE_MODULE.

Now, when main.wasm linked with -s MAIN_MODULE and with someModule.a and a.wasm
I get a duplicate symbol error because someModule.a and main.wasm has both probably linked with libc.
but, as far I understand, SIDE_MODULE cannot be declared to static library - someModule.a .
so , how it can be resolved if I need to keep the above modules structure - 2 dynamic modules and one static?

[sbc100]

It should be fine to link static libraries into your main module. Static libraries such as someModule.a cannot contain libc since libc only gets linked in the main module.

What symbols are you seeing duplicated? Can you show the full failing link command and its output?

[aharondavid]

yes, here you go:

emcc : warning : -sMAIN_MODULE + pthreads is experimental [-Wexperimental]
2>emcc : warning : USE_PTHREADS + ALLOW_MEMORY_GROWTH may run non-wasm code slowly, see WebAssembly/design#1271 [-Wpthreads-mem-growth]
2>wasm-ld : error : duplicate symbol: fmemopen
2>>>> defined in C:/inetpub/wwwroot/SG/TestEmscripten/Core.Emscripten.wasm(sl_globals.o)
2>>>> defined in C:\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\pic\libc-mt-debug.a(fmemopen.o)

wasm-ld : error : duplicate symbol: mkdir
2>>>> defined in C:/inetpub/wwwroot/SG/TestEmscripten/Core.Emscripten.wasm(sl_core_emscripten.o)
2>>>> defined in C:\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\pic\libc-mt-debug.a(mkdir.o)
2>

2>wasm-ld : error : duplicate symbol: swscanf
2>>>> defined in C:/inetpub/wwwroot/SG/TestEmscripten/Core.Emscripten.wasm(sl_core_emscripten.o)
2>>>> defined in C:\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\pic\libc-mt-debug.a(swscanf.o)
2>

2>wasm-ld : error : duplicate symbol: wcsstr
2>>>> defined in C:/inetpub/wwwroot/SG/TestEmscripten/Core.Emscripten.wasm(sl_core_emscripten.o)
2>>>> defined in C:\emsdk\upstream\emscripten\cache\sysroot\lib\wasm32-emscripten\pic\libc-mt-debug.a(wcsstr.o)
2>

[sbc100]

The problem here is that sl_core_emscripten.o defined a bunch of libc symbols.. do you know why that is? Where does that object come from? Do you know why it defines those symbols?

Also, what is Core.Emscripten.wasm using the .wasm extension? From the error message it looks like actually .a archive created by emar, so should probably be called .a.

Also, I still don't see the command line that failed.. in order to help you the most it would be useful to see that. (if you are using cmake you can build with make VERBOSE=1 .. or just use ninja, if you want to see the full failing command line).

[aharondavid]

Here is the command line of :
C:\emsdk\upstream\emscripten\\emcc.bat Emscripten/Debug/HttpNetFile.o Emscripten/Debug/IOFILE.o Emscripten/Debug/Source.o C:/Projects/simple_opengl-master/TheMainProject/libs/libxml2.a C:/Projects/simple_opengl-master/TheMainProject/libs/libgdal.a C:/Projects/simple_opengl-master/TheMainProject/libs/libproj.a C:/inetpub/wwwroot/SG/TestEmscripten/Core.Emscripten.wasm C:/inetpub/wwwroot/SG/TestEmscripten/SimpleProject.wasm -fexceptions -s WASM_BIGINT -s FETCH=1 -g --preload-file com.skyline.terraexplorer --bind -fexceptions -s USE_PTHREADS -s PTHREAD_POOL_SIZE=navigator.hardwareConcurrency -s ALLOW_MEMORY_GROWTH=1 -s MAIN_MODULE -O0 -o C:/inetpub/wwwroot/SG/TestEmscripten/TheMainProject.js

I build my project by Emscripten Plugin for Visual Studio, and it is not expose the command line that build the Core.Emscripten.wasm above, but here is the flags that passed to the emcc:

AdditionalOptions=-Wsign-compare -Wno-import -Wformat=2 -Wmain -Wmissing-braces -w -Wformat-nonliteral -Wformat-nonliteral  -fpermissive -pthread   
PreprocessorDefinitions=__EMSCRIPTEN_PTHREADS__;_MB_CAPABLE;UNICODE;_UNICODE;_LIBCPP_HAS_NO_OFF_T_FUNCTIONS;HAVE_LONG_LONG;

and flags to the linker: --bind -s SIDE_MODULE

I hope that it help