Linking errors with nwindowGetDefault() about libnx

[fincs]

First of all, can you post your CMakeLists.txt? libnx is already linked in automatically as a system lib, you don't need to manually ask for it. During our testing, we found it sufficed to use this to link in deko3d:

target_link_libraries (${PROJECT_NAME} PRIVATE
	deko3dd
)

@fincs I managed to reproduce the issue with a basic sample. It turns out nwindowGetDefault() cannot be called from C++, only from C. I've attached a reproduction to this comment. If you rename main.cpp to main.c and update the CMakeLists.txt to reference it, the build will succeed, and by default it will fail.

For reference I generate a Makefile with the following command:

cmake -G "Unix Makefiles" -DCMAKE_TOOLCHAIN_FILE=../cmake/DevkitA64Libnx.cmake ..

sample.zip

Here's the full build output demonstrating the issue:

Scanning dependencies of target sample
[ 25%] Building CXX object CMakeFiles/sample.dir/main.cpp.obj
/Users/lyptt/Desktop/sample/main.cpp: In function 'int main()':
/Users/lyptt/Desktop/sample/main.cpp:4:12: warning: variable 'a' set but not used [-Wunused-but-set-variable]
    4 |   NWindow* a = nwindowGetDefault();
      |            ^
[ 50%] Linking CXX executable sample
/opt/devkitpro/devkitA64/bin/../lib/gcc/aarch64-none-elf/11.1.0/../../../../aarch64-none-elf/bin/ld: /opt/devkitpro/devkitA64/bin/../lib/gcc/aarch64-none-elf/11.1.0/../../../../aarch64-none-elf/bin/ld: DWARF error: can't find .debug_ranges section.
CMakeFiles/sample.dir/main.cpp.obj: in function `main':
main.cpp:(.text.startup.main+0x8): undefined reference to `nwindowGetDefault()'
collect2: error: ld returned 1 exit status
make[2]: *** [sample] Error 1
make[1]: *** [CMakeFiles/sample.dir/all] Error 2
make: *** [all] Error 2

[fincs]

As I suspected, you're using third party/unsupported cmake machinery. You might be interested to know that, as of recently, we've added official cmake toolchain support. You can get it by installing or refreshing your switch-dev package group installation, i.e. sudo dkp-pacman -S --needed switch-dev.

In order to use it, we offer a wrapper script that sets the correct variables: /opt/devkitpro/portlibs/switch/bin/aarch64-none-elf-cmake. It is advised to purge your project of traces of previous unsupported machinery, and move to our new official support.

Setting up a basic project with deko3d should be as simple as this:

cmake_minimum_required (VERSION 3.7)
project (MyProjectName)

add_executable (${PROJECT_NAME}
	# Source code files go here
	source/main.cpp
)

dkp_add_asset_target (${PROJECT_NAME}_romfs romfs)

nx_generate_nacp (${PROJECT_NAME}.nacp
	NAME "Your Project Name"
	AUTHOR "Author Name"
)

nx_create_nro (${PROJECT_NAME}
	NACP ${PROJECT_NAME}.nacp
	ROMFS ${PROJECT_NAME}_romfs
)

target_compile_options (${PROJECT_NAME} PRIVATE
	-g -Wall -O2
	$<$<COMPILE_LANGUAGE:CXX>:-fno-exceptions -fno-rtti>
)

target_link_libraries (${PROJECT_NAME} PRIVATE
	deko3dd
)

# Shaders
nx_add_shader_program (simple_vsh simple_vsh.glsl vert)
nx_add_shader_program (simple_fsh simple_fsh.glsl frag)

dkp_install_assets (${PROJECT_NAME}_romfs
	DESTINATION shaders
	TARGETS
		simple_vsh
		simple_fsh
		# etc
)

@fincs I've confirmed that C++ name mangling is the issue here. If it's intended that this API has C linkage, you'll need to wrap the header definitions in an extern "C" block. Doing this manually myself on my local copy of native_window.h fixed the linking issue.

I've attached the modified file so you can see the change.

native_window.h.zip

Thanks for a sample of the supported approach, I couldn't find any examples yesterday of using libnx with cmake when I started playing around with it, so I had to go my own route.

[fincs]

Oh and one more thing. The header you need to include is #include <switch.h>, which does have C++ guards. Trying to manually include libnx headers piecemeal is currently not supported.

Gotcha, I didn't see any documentation relating to that quirk of the toolchain either. I'll bear that in mind from now on. Thanks for the help.