dependency() should have an option to override globally defined paths

[themightyoarfish]

I might be misunderstanding something completely, but here goes.

Describe the bug
dependency() cannot be told to look for a dependency in a specific prefix.

To Reproduce
Assume you have multiple versions of a library installed in different installation prefixes. During development you might want to switch between them (e.g. debug and release builds). But you can only set cmake_prefix_path and the like globally, there is no way I can see to override this path for a single dependency. The default_options argument to dependency() cannot be used to override cmake_prefix_path.

project('foo', 'cpp',
  version : '0.1',
  default_options : ['warning_level=3',
                     'cpp_std=c++17',
                     'cmake_prefix_path=/custom/prefix1',
                     'pkg_config_path=/custom/prefix1/lib/pkgconfig'])

cv2 = dependency('OpenCV', version : '>=4.0.0', method : 'cmake')
pcl = dependency('PCL', version : '>=1.12', components : [ 'common' ])

exe = executable('foo', 'foo.cpp',
  dependencies : [ cv2, pcl ])

Expected behavior

An option to modify the environment for the execution of the function should be available. The doc sounds like default_options should be for this purpose, but it seems I am misunderstanding it

system parameters

• native
• macOs 12.4
• Python 3.8.8
• Meson verion 0.63.0
• Ninja 1.11.0

[eli-schwartz]

Why can't you just use the global path for this? If you have multiple versions of a dependency installed to different install paths, then I would assume those dependencies are isolated on their own. Adding that path to the global path will only affect one dependency anyway.

[themightyoarfish]

If I have the same library version installed once in debug build and once in release build, how do I configure to use either one? I can only set the global path, which has the side effect of influencing other dependencies then.

…

On October 9, 2022 7:31:55 PM GMT+02:00, Eli Schwartz ***@***.***> wrote: Why can't you just use the global path for this? If you have multiple versions of a dependency installed to different install paths, then I would assume those dependencies are isolated on their own. Adding that path to the global path will only affect one dependency anyway. -- Reply to this email directly or view it on GitHub: #10910 (comment) You are receiving this because you authored the thread. Message ID: ***@***.***>

[eli-schwartz]

How does it influence other dependencies?

[themightyoarfish]

Because the global path influences where they are found, in case of multiple versions.

[eli-schwartz]

Shouldn't you just be adding one version of the original dependency to your cmake path?

It's not really clear to me what you're trying to do here.

[themightyoarfish]

Let me try again:

• Dependency A debug build is in prefix prefixDebug/
• Dependency A release build is in prefix prefixRelease/
• Dependency B debug build is in prefix prefixDebug/
• Dependency B release build is in prefix prefixRelease/
  I want meson to find dependency A's debug build, but dependency B's release build.

CMake has the PATHS and HINTS argument to find_package() for this.

[eli-schwartz]

And how do you toggle between these without editing CMakeLists.txt?

Wouldn't it make more sense to have:

• Dependency A debug build is in prefix prefixADebug/

• Dependency A release build is in prefix prefixARelease/

• Dependency B debug build is in prefix prefixBDebug/

• Dependency B release build is in prefix prefixBRelease/

Since prefixDebug/ is not intended to be a general environment for finding multiple software components, it seems odd to store multiple software components in it.

[eli-schwartz]

Anyway: https://mesonbuild.com/Dependencies.html#cmake

You can set cmake_module_path inside the dependency() kwargs, which corresponds to CMake's -DCMAKE_MODULE_PATH but not to -DCMAKE_PREFIX_PATH. You will unfortunately then have to edit meson.build just like you'd have to edit CMakeLists.txt, which I would say is suboptimal, but if you really want it...

[themightyoarfish]

I need to set the prefix path, not the module path.