Propagation of compile definitions

Usage
1

Hi,

I’ve got a static library target L where I do:

target_compile_definitions(L PUBLIC SOMESYMBOL)

In an application A, I’m linking against L:

target_link_library(A PRIVATE L)

I’m then expecting A to inherit SOMESYMBOL but:

get_target_property(ouputvar A <INTERFACE_>COMPILE_DEFINITIONS)
message(${ouputvar})

displays only

outputvar-NOTFOUND

What is happening?

Regards
A.

2

They do propagate, you can see it when running the build.

cmake_minimum_required(VERSION 3.15)
project(mypkg CXX)


add_library(L src/mypkg.cpp)
target_compile_definitions(L PUBLIC SOMESYMBOL)
add_library(A src/mypkg.cpp)
target_link_libraries(A PRIVATE L)

Output (note SOMESYMBOL present in both commands):

# ninja -v -n
[1/4] L:\Software\MICROS~2\2022\COMMUN~1\VC\Tools\MSVC\1444~1.352\bin\Hostx64\x64\cl.exe  /nologo /TP -DSOMESYMBOL  /DWIN32 /D_WINDOWS /GR /EHsc /Zi /Ob0 /Od /RTC1 -MDd /showIncludes /FoCMakeFiles\L.dir\src\mypkg.cpp.obj /FdCMakeFiles\L.dir\L.pdb /FS -c L:\oblivion\conan-test\src\mypkg.cpp
[2/4] L:\Software\MICROS~2\2022\COMMUN~1\VC\Tools\MSVC\1444~1.352\bin\Hostx64\x64\cl.exe  /nologo /TP -DSOMESYMBOL  /DWIN32 /D_WINDOWS /GR /EHsc /Zi /Ob0 /Od /RTC1 -MDd /showIncludes /FoCMakeFiles\A.dir\src\mypkg.cpp.obj /FdCMakeFiles\A.dir\A.pdb /FS -c L:\oblivion\conan-test\src\mypkg.cpp

When you do target_link_library you don’t copy properties of all linked targets to another, you just reference the target as linked to another and it’s properties then inherited later during project build files generation.

3

Thanks Andrej,

There is no way to test for the symbol from A CMakeLists.txt at configuration time?

At worse, can I display a message at build time, based on the existence of the symbol?

Regards,
A.