[CMake] Handling of generator expressions

[Roberto Di Remigio]

Dear Oleksii,
indeed it works! Thank you! I have opened an issue on the CMake repository:
https://gitlab.kitware.com/cmake/cmake/issues/17501
I think it could still be a bug, since target_compile_definitions and
target_link_libraries seem to evaluate the expression differently.
  All the best,
   Roberto

On Wed, Nov 22, 2017 at 11:40 AM, Oleksii Vilchanskyi <
oleksii.vilchanskyi at gmail.com> wrote:

> UPD. forgot to CC the mailing list
>
> Hi,
>
> I am also confused by this and decided to test it. I found a long thread
> from 2012
> <https://cmake.org/pipermail/cmake-developers/2012-August/
> thread.html#16509>
> that discusses list expansion issues. It doesn't tell though whether the
> patch was mainlined.
>
> tldr; if you quote the whole genexpr, the list will expand properly.
> Below is the working code.
>
> ----------------------------------------------------------------------
> cmake_minimum_required(VERSION 3.3 FATAL_ERROR)
>
> project(recipe-09 CXX)
>
> set(CMAKE_CXX_STANDARD 11)
> set(CMAKE_CXX_EXTENSIONS OFF)
> set(CMAKE_CXX_STANDARD_REQUIRED ON)
>
> list(APPEND CXX_BASIC_FLAGS "-g3" "-O1")
>
> include(CheckCXXCompilerFlag)
>
> set(ASAN_FLAGS "-fsanitize=address -fno-omit-frame-pointer")
> set(CMAKE_REQUIRED_FLAGS ${ASAN_FLAGS})
> check_cxx_compiler_flag(${ASAN_FLAGS} asan_works)
> unset(CMAKE_REQUIRED_FLAGS)
>
> add_executable(asan-example asan-example.cpp)
> string(REPLACE " " ";" _asan_flags ${ASAN_FLAGS})
> target_compile_options(asan-example
>   PUBLIC
>     ${CXX_BASIC_FLAGS}
>     $<$<BOOL:${asan_works}>:${_asan_flags}>
>   )
> target_link_libraries(asan-example
>   PUBLIC
>     "$<$<BOOL:${asan_works}>:${_asan_flags}>" # <-- NOTE THIS
>   )
> ----------------------------------------------------------------------
>
> On 19.11.2017 19:16, Roberto Di Remigio wrote:
> > Hello,
> > I am trying to compile the following code snippet:
> >
> > int main(int argc, char ** argv) {
> >   int stack_array[100];
> >   stack_array[1] = 0;
> >   return stack_array[argc + 100]; // BOOM
> > }
> >
> > The followin CMakeLists.txt works fine, but you can notice that
> > target_compile_options takes a list, while target_link_libraries takes a
> > string. Always using the string will result in a compilation error,
> > because the compiler flags are passed quoted to the compiler. Always
> > using the list doesn't work either, because the generator expression is
> > evaluated as $<1:-fsanitize=address -fno-omit-frame-pointer> and then
> > passed as-is to the linker, which doesn't know what to do with it.
> > Is this supposed to be like this? If yes, what's the rationale?
> > Thanks in advance!
> >   Roberto
> >
> > cmake_minimum_required(VERSION 3.3 FATAL_ERROR)
> >
> > project(recipe-09 CXX)
> >
> > set(CMAKE_CXX_STANDARD 11)
> > set(CMAKE_CXX_EXTENSIONS OFF)
> > set(CMAKE_CXX_STANDARD_REQUIRED ON)
> >
> > list(APPEND CXX_BASIC_FLAGS "-g3" "-O1")
> >
> > include(CheckCXXCompilerFlag)
> >
> > set(ASAN_FLAGS "-fsanitize=address -fno-omit-frame-pointer")
> > set(CMAKE_REQUIRED_FLAGS ${ASAN_FLAGS})
> > check_cxx_compiler_flag(${ASAN_FLAGS} asan_works)
> > unset(CMAKE_REQUIRED_FLAGS)
> >
> > add_executable(asan-example asan-example.cpp)
> > string(REPLACE " " ";" _asan_flags ${ASAN_FLAGS})
> > target_compile_options(asan-example
> >   PUBLIC
> >     ${CXX_BASIC_FLAGS}
> >     $<$<BOOL:${asan_works}>:${_asan_flags}>
> >   )
> > target_link_libraries(asan-example
> >   PUBLIC
> >     $<$<BOOL:${asan_works}>:${ASAN_FLAGS}>
> >   )
> >
> >
>
> --
> Regards,
> Oleksii Vilchanskyi
> PGP:0x8D3A0E046BDE941F2A53867CE3FD952D48C0B338
>
>


-- 
Roberto Di Remigio
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/cmake/attachments/20171122/c35ec803/attachment.html>