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Dylan Baker authored
In the old days (0.42.x), when mesa's meson system was written the recommendation for handling conditional dependencies was to define them as empty lists. When meson would evaluate the dependencies of a target it would recursively flatten all of the arguments, and empty lists would be removed. There are some problems with this, among them that lists and dependencies have different methods (namely .found()), so the recommendation changed to use `dependency('', required : false)` for such cases. This has the advantage of providing a .found() method, so there is no need to do things like `dep_foo != [] and dep_foo.found()`, such a dependency should never exist. I've tested this with 0.42 (the minimum we claim to support) and 0.45. On 0.45 this removes warnings about comparing unlike types, such as: meson.build:1337: WARNING: Trying to compare values of different types (DependencyHolder, list) using !=. v2: - Use dependency('', required : false) instead of declare_dependency(), the later will always report that it is found, which is not what we want. Signed-off-by: Dylan Baker <dylan.c.baker@intel.com> Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
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