How to forward dependencies in Meson?

Question

Say I have the following dependency chain, dependency A depends on B which depends on C. All 3 are specified as dep objects.

The headers of B include headers in C.

I am finding that when I compile A I must list C as an explicit dependency even if B is already listed as a dependency, otherwise C's headers are not available in A's translation units.

How can I instruct meson to automatically include C's headers wherever B is used as a dependency?

Answer 1

I think you need to use declare_dependency
something like this should work.

C_dep = declare_dependency(include_directories : C_includes)
B_dep = declare_dependency(include_directories : B_includes, dependencies : [C_dep])
A_dep = static_library('a_lib', dependencies : [B_dep]) # or whatever your usecase is

Answer 2

You must specify your C dependency with header path included via include_directories:

c_dep = declare_dependency(
  dependencies: c_lib,
  include_directories: include_directories(c_inc_dirs),
)

Then add C in your B dependency, like this:

b_deps = []
b_deps += dependency('clib', fallback:['clib', 'c_dep'])

b_dep = declare_dependency(
    link_with: b_lib,
    include_directories: b_inc_dirs,
    dependencies: b_deps)

The A should also add normal dependency to B, and not to C because C is already added in B.