Build order issue using a cmake subproject dependency

[EmmanuelP]

Hi,

Before reporting it as an issue in meson, I'd like to know if I'm doing it wrong.

I have a pretty simple repository with open62541 dependency as a subproject. open62541 build system is based on cmake. The meson part is the following:

open62541 = cmake.subproject('open62541', options:open62541_options)
opc_dep = open62541.dependency('open62541')

opctest_dependencies = [opc_dep]

apps = ['producer', 'consumer']

foreach a: apps
  executable(a, a + '.c', dependencies: opctest_dependencies, install: true)
endforeach

The problem is when I invoke ninja, the two executables are always built before the open62541 subproject. Is there something wrong in the way I have declared the dependencies ?

The full project is here: https://github.com/EmmanuelP/opctest

[andy5995]

@EmmanuelP Looking at the relevant docs, it appears you'll need to make some changes.

Also, could you edit your post to correct the link to your GitHub repo? It's linking to the discussion you created.

[andy5995]

@wbthomason This is the output I get using the current state of your git repo:

[andy@prometheus cpzlib]$ CXX=clang++ meson build && meson compile -C build
The Meson build system
Version: 0.61.1
Source dir: /home/andy/src/cpzlib
Build dir: /home/andy/src/cpzlib/build
Build type: native build
Project name: cpzlib
Project version: 0.1
C++ compiler for the host machine: clang++ (clang 13.0.0 "clang version 13.0.0")
C++ linker for the host machine: clang++ ld.bfd 2.36.1
Host machine cpu family: x86_64
Host machine cpu: x86_64
Found pkg-config: /home/linuxbrew/.linuxbrew/bin/pkg-config (0.29.2)
Found CMake: /usr/bin/cmake (3.22.2)
Run-time dependency eigen3 found: NO (tried pkgconfig and cmake)
Looking for a fallback subproject for the dependency eigen3

Executing subproject eigen 

eigen| Project name: eigen
eigen| Project version: 3.3.9
eigen| C++ compiler for the host machine: clang++ (clang 13.0.0 "clang version 13.0.0")
eigen| C++ linker for the host machine: clang++ ld.bfd 2.36.1
eigen| Build targets in project: 0
eigen| Subproject eigen finished.

WARNING: Variable 'eigen3' in the subproject 'subprojects/eigen-3.3.9' is not found
Dependency eigen3 from subproject subprojects/eigen-3.3.9 found: NO

meson.build:7:0: ERROR: Dependency 'eigen3' is required but not found.

[wbthomason]

@andy5995 I cannot reproduce that (I just tried a fresh clone and build, which works as expected). Perhaps this is because I have Eigen installed on my system already, and do not need to rely on the subproject?

[wbthomason]

I'll note that I have another (currently private) project also successfully using a CMake subproject dependency; the relevant part of my meson.build is:

# Dependencies
cmake = import('cmake')

autodiff = dependency('autodiff', required: false)
if not autodiff.found()
  autodiff_cmake_opts = cmake.subproject_options()
  autodiff_cmake_opts.add_cmake_defines({'AUTODIFF_BUILD_EXAMPLES': false})
  autodiff_cmake_opts.set_override_option('cpp_std', 'c++20')
  autodiff_cmake = cmake.subproject('autodiff', options: autodiff_cmake_opts)
  autodiff = autodiff_cmake.dependency('autodiff')
endif

[andy5995]

@andy5995 I cannot reproduce that (I just tried a fresh clone and build, which works as expected). Perhaps this is because I have Eigen installed on my system already, and do not need to rely on the subproject?

@wbthomason Just wanted to let you know that after I installed eigen (on Manjaro), cpzlib builds (and using g++ 11.1.0).

[wbthomason]

Thanks - there must be a problem with my eigen subproject setup.

[andy5995]

@eli-schwartz @jpakkane I referred to this meson.build a little. Isn't the dependency supposed to build just by using those two lines within the 'if' condition there? I couldn't get this to work without using the fallback keyword.

[eli-schwartz]

The fallback kwarg is not the same as an explicit subproject() invocation. Also automatic fallback assumes the wrapped subproject uses meson, not cmake.