Link issues using meson on Windows

[mitchgrout]

I'm trying to get a basic slint project working within Meson instead of CMake. Meson is able to work with CMake projects, so it should be able to pick up on system-installed copies of slint, as these will be bundled with the relevant .cmake files. I've attached a minimal example here:

# meson.build
project('example', 'cpp', default_options: ['cpp_std=c++20'])

slint = dependency('slint') # Choice based on C++ example CMake, `find_package(Slint ...)`
slint_compiler = find_program('slint-compiler')
sources = custom_target(input: 'example.slint', output: 'example.hpp', command: [slint_compiler, '@INPUT@', '-o', '@OUTPUT@'])
executable('example', 'main.cpp', sources, dependencies: slint)

// example.slint
export component MainWindow inherits Window {
  Rectangle { background: red; }
}

// main.cpp
#include <example.hpp>
int main()
{
  auto window = MainWindow::create();
  window->show();
  return 0;
}

---

Running meson setup build shows that meson is able to find the installation for slint (via the .cmake files), but trying to build the target executable will fail linkage with...

$ ninja -C build
ninja: Entering directory `build'
[3/3] Linking target example.exe
FAILED: example.exe
"c++"  -o example.exe example.exe.p/main.cpp.obj "-Wl,--allow-shlib-undefined" "-Wl,--subsystem,console" "-Wl,--start-group" "-lkernel32" "-luser32" "-lgdi32" "-lwinspool" "-lshell32" "-lole32" "-loleaut32" "-luuid" "-lcomdlg32" "-ladvapi32" "-Wl,--end-group"
ld.exe: example.exe.p/main.cpp.obj: in function `register_item_tree':
${SLINT}/include/slint/slint.h:218: undefined reference to `slint_register_item_tree'
ld.exe: example.exe.p/main.cpp.obj: in function `slint::SharedString::SharedString()':
${SLINT}/include/slint/slint_string.h:26: undefined reference to `slint_shared_string_from_bytes'
...

I would expect to see -lslint_cpp or similar appear in here, but it is absent which would explain the link errors. My understanding of CMake is not the best, but it appears that SlintTargets.cmake defines the library as INTERFACE, i.e. header-only, meaning we won't get any linkage:

# lib/cmake/Slint/SlintTargets.cmake (line 59 - 66)
add_library(Slint::Slint INTERFACE IMPORTED)

set_target_properties(Slint::Slint PROPERTIES
  INTERFACE_COMPILE_FEATURES "cxx_std_20"
  # INTERFACE_COMPILE_OPTIONS "/bigobj"
  INTERFACE_INCLUDE_DIRECTORIES "${_IMPORT_PREFIX}/include/slint"
  INTERFACE_LINK_LIBRARIES "Slint::slint-cpp"
)

The other libraries defined in SlintTargets.cmake (slint-cpp, slint-cpp-shared) are not detected by meson. My assumption is then that I should depend on these targets. Any advice on getting this working?

[tronical]

INTERFACE_LINK_LIBRARIES "Slint::slint-cpp"

With cmake this results in any target linking against Slint::Slint to also link against Slint::slint-cpp.

[mitchgrout]

Looks like it could be a meson problem; the dependency is pretty odd:

{
      "name": "slint",
      "type": "cmake",
      "version": "1.4.1",
      "compile_args": [
        "-I<path/to/slint>/include/slint"
      ],
      "link_args": [],
      "include_directories": [],
      "sources": [],
      "extra_files": [],
      "dependencies": [],
      "depends": [],
      "meson_variables": [
        "slint"
      ]
    }

I'd expect include paths to be loaded into include_directories and the .dll in link_args. I'll do some more digging

[tronical]

👍 alternatively, if there is some meta data that we could produce so that meson could consume slint directly, let us know :)

[mitchgrout]

Adding an explicit INTERFACE_LINK_LIBRARIES to the slint-cpp-shared properties will cause meson to pick up the .dll as a link argument; I'm assuming one of the existing properties being set allows cmake to pick it up?

# Existing:
set_target_properties(slint-cpp-shared PROPERTIES IMPORTED_LOCATION;${_IMPORT_PREFIX}/lib/slint_cpp.dll;IMPORTED_LOCATION_DEBUG;${_IMPORT_PREFIX}/lib/slint_cpp.dll;IMPORTED_LOCATION_RELEASE;${_IMPORT_PREFIX}/lib/slint_cpp.dll;IMPORTED_LOCATION_RELWITHDEBINFO;${_IMPORT_PREFIX}/lib/slint_cpp.dll;IMPORTED_LOCATION_MINSIZEREL;${_IMPORT_PREFIX}/lib/slint_cpp.dll;IMPORTED_IMPLIB;${_IMPORT_PREFIX}/lib/slint_cpp.dll.lib;IMPORTED_IMPLIB_DEBUG;${_IMPORT_PREFIX}/lib/slint_cpp.dll.lib;IMPORTED_IMPLIB_RELEASE;${_IMPORT_PREFIX}/lib/slint_cpp.dll.lib;IMPORTED_IMPLIB_RELWITHDEBINFO;${_IMPORT_PREFIX}/lib/slint_cpp.dll.lib;IMPORTED_IMPLIB_MINSIZEREL;${_IMPORT_PREFIX}/lib/slint_cpp.dll.lib;IMPORTED_NO_SONAME;TRUE)
# Adding:
set_target_properties(slint-cpp-shared PROPERTIES INTERFACE_LINK_LIBRARIES "${_IMPORT_PREFIX}/lib/slint_cpp.dll")