How to set library flags after source file in cmake?

Question

I'm trying to compile a project using hwloc with CMake. However, I get a ton of undefined reference errors when linking:

undefined reference to `hwloc_get_type_depth'
undefined reference to `hwloc_bitmap_zero'
[...]

According to this answer to a similar question the order of flags is important.

So, how can I generate a command like this in CMake? :

g++ -Wall -std=c++11 source.cpp-lhwloc

Excerpt from my CMakeLists.txt:

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -std=c++11 -lhwloc")

set(SOURCE_FILES source.cpp)
add_executable(source ${SOURCE_FILES})

Any help is greatly appreciated!

Edit: My question was proposed as a possible duplicate of this one, however the flag I wanted to add was to link against a library and not a normal compile flag as seems to be the case in the above mentioned question. @Edgar Rokyan provided the right answer for my problem.

Possible duplicate of [How to add linker or compile flag in cmake file?](https://stackoverflow.com/questions/11783932/how-to-add-linker-or-compile-flag-in-cmake-file) — Alex Huszagh, Jul 01 '17 at 21:33
Possible duplicate of [How to add "-l" (ell) compiler flag in CMake](https://stackoverflow.com/questions/43136418/how-to-add-l-ell-compiler-flag-in-cmake) — Tsyvarev, Jul 01 '17 at 22:09

score 5 · Accepted Answer · answered Jul 01 '17 at 21:29

5

If you need to link against hwloc library you might use target_link_libraries command:

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -std=c++11") # <== remove *-lhwloc*

set(SOURCE_FILES source.cpp)
add_executable(source ${SOURCE_FILES})

target_link_libraries(source hwloc) # <== add this line

answered Jul 01 '17 at 21:29

Edgar Rokjān

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Thank you very much! That fixed it. I'll accept your answer as soon as possible. – hsvar Jul 01 '17 at 21:36

How to set library flags after source file in cmake?

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