Linking a library to a header-only one

Question

I have two libraries:

• a;
• b: a header-only library which depends on a.

I am not sure if it is possible to link b to a. If so, how can I do it?

In fact, I have a third library c that depends on both. This CMake script does not work:

[...]

add_library(a ${a_SRC})
target_link_libraries(a CONAN_PKG::<foo>)

add_library(b INTERFACE)
target_sources(b INTERFACE ${b_SRC})
target_include_directories(b INTERFACE "${PROJECT_SOURCE_DIR}/src/include/b/")
target_link_libraries(b INTERFACE a) # This has no effect, I think!

add_executable(c ${c_SRC})
target_link_libraries(c b a)

I used a workaround by adding the source files of a into the definition of c.

[...]
add_executable(c ${c_SRC} ${a_SRC})
[...]