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I'm using CMake for a project that comes in two versions, one of which requires -lglapi and the other does not.

So far the lines we used look like that: 

SET(CMAKE_C_FLAGS "-O3 -xSSE3 -restrict -lpthread -lX11 -ldrm") SET(CMAKE_CXX_FLAGS "-O3 -xSSE3 -restrict -lpthread -lX11 -ldrm")

I added an if statement in my CMakeList.txt exactly after those lines: 

if(SINGLE_MODE) SET(CMAKE_C_FLAGS ${CMAKE_C_FLAGS} " -lglapi") SET(CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS} " -lglapi") endif(SINGLE_MODE)

The SINGLE_MODE variable is defined a little up. When I use the message command to display the content of the flag variables it looks alright:

-O3 -xSSE3 -restrict -lpthread -lX11 -ldrm -lglapi

But when I start compiling I am running into a compile error. Using the verbose mode I realized that in the compiler call it looks like that: 

-O3 -xSSE3 -restrict -lpthread -lX11 -ldrm; -lglapi

I.e. somehow a semicolon got added before adding the -lglapi to the list.

Did anyone here encounter a similar issue and knows a way to fix this issue? I've googled quite a while and studied the CMake manual but couldn't see what I did wrong here.

Thanks, Tobias

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  • 6
    Did you try SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -lglapi")? Commented Apr 27, 2015 at 16:42
  • @jpo38 You should make an answer and get your deserved reputation :) Commented Apr 27, 2015 at 16:46
  • @jpo38, thank you. That did the trick. Should have thought of that myself but after looking at something for too long, you kinda get blind for that. Commented Apr 27, 2015 at 16:47
  • Thanks. As I have no CMake installed on my current computer, I could not test. Prefered to have your feedback before posting an untested answer to avoid getting any downvotes....;-). Now ready for upvotes! Commented Apr 27, 2015 at 16:50

3 Answers 3

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34

Try to do this instead:

if(SINGLE_MODE) SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -lglapi") SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -lglapi") endif(SINGLE_MODE)

Then, you are sure you append -lglapi to the existing ${CMAKE_CXX_FLAGS} string. Else, looks like something like a CMake list is being created.

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3 Comments

This is very boilerplate. Is there a shorter solution?
@nowox: Not any that I'm aware of
Oh :( I don't really know CMake, but is it not possible to use list(APPEND?
22

Since CMake 3.4 you do:

string(APPEND CMAKE_CXX_FLAGS " -lglapi")

This very handy when you want to set the flags only for one language (C++ in the example above), but if you want to set the same flags for all languages, you can simply do:

add_compile_options(-lglapi)

Both commands change the flags for the whole directory, if you want to set the flags for only one target, do:

target_compile_options(my_lib PUBLIC -lglapi)

Flags on a target can either be PUBLIC, PRIVATE or INTERFACE, allowing to transitively forward the flags from one target to the other.

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0

Just for the particular case where you want to add compiler and linker options (like for --coverage option), the following syntax add the flags to both the linker and compiler:

SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} --coverage") SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} --coverage")

(above commands add --coverage option to both compiler and flags options for C and C++)

Otherwise, if you prefer to use new CMake commands (add_compile_options and add_link_options), don't forget to add to the linker option too:

add_compile_options(--coverage) add_link_options(--coverage)

(above commands add --coverage option to both compiler and flags options for C and C++)

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