Hi,
The goal that you have is fully supported by CMake. You have just run
into a bug in CMake, and you should report this to
https://gitlab.kitware.com/cmake/cmake/issues .
Basically at a very high level the name out the add_executable target
`callback_generator` is the same as the internal name that CMake is
using for the add_custom_command. This than causes some logic in CMake
(cmTargetTraceDependencies) to incorrectly build another link between
the add_custom_command and your add_executable.
The easiest way to solve this issue is name the add_executable target
to have a different name than the output of your custom command minus
file extension. So maybe something like `callback_generator_exec`
On Fri, May 24, 2019 at 2:02 PM Bill Somerville <b...@classdesign.com> wrote:
>
> On 13/05/2019 12:03, Bill Somerville wrote:
>
> Hi folks,
>
> I am struggling to understand what the problem is with this:
>
> find_program (GO go)
> set (GOPATH "${CMAKE_CURRENT_BINARY_DIR}/go")
> file (MAKE_DIRECTORY ${GOPATH})
>
> set (sources ${CMAKE_CURRENT_SOURCE_DIR}/callback_generator.go)
> set (build_command ${GO} build)
> set (output callback_generator${CMAKE_EXECUTABLE_SUFFIX})
> add_custom_command (OUTPUT ${output}
> COMMAND ${CMAKE_COMMAND} -E env GOPATH=${GOPATH}
> CGO_CFLAGS=${CMAKE_CGO_CFLAGS} ${build_command} -o ${output}
> ${CMAKE_GO_FLAGS} ${sources}
> DEPENDS ${sources}
> VERBATIM)
> add_custom_target (callback_generator_target DEPENDS
> ${CMAKE_CURRENT_BINARY_DIR}/${output})
> add_executable (callback_generator IMPORTED)
> set_target_properties (callback_generator
> PROPERTIES
> IMPORTED_LOCATION ${CMAKE_CURRENT_BINARY_DIR}/${output}
> )
> add_dependencies (callback_generator callback_generator_target)
>
> add_custom_target (server ALL DEPENDS callback_generator)
>
> which gives this error:
>
> >cmake --version
> cmake --version
> cmake version 3.14.3
>
> >cmake -G "MinGW Makefiles" ..\..
> cmake -G "MinGW Makefiles" ..\..
> -- Configuring done
> CMake Error: The inter-target dependency graph contains the following
> strongly connected component (cycle):
> "callback_generator_target" of type UTILITY
> depends on "callback_generator_target" (strong)
> The component contains at least one cycle consisting of strong dependencies
> (created by add_dependencies) that cannot be broken.
>
> The set_target_properties () call seems to be part of the problem but I don't
> understand why.
>
> Regards
> Bill Somerville.
>
> Hi again,
>
> answering my own post since no one has replied. Clearly my question was too
> specific. Let me try again with a more general question. I have tools that
> can generate executables (programs, static libraries, and shared libraries,
> including DLL import libraries on MS Windows). These tools are not directly
> supported by CMake but they are both needed within a project that uses them
> and installs them as the project artefacts. How do I integrate, for example a
> shared library, into a CMake project as if it were produced by a supported
> toolchain like C or C++? The library is produced by an add_custom_target()
> command (not add_custom_command() since the underlying tools do their own
> dependency checking so it is right to run the target commands every build). I
> need to have a target that I can use in target_link_libraries() and
> install(TARGETS ...) just like one would with a CMake generated library made
> with add_library() and programs made with add_executable().
>
> If it helps the tools that are not supported by CMake are the Go language
> build tools. The project builds some Go programs as utilities but the main
> project artefact is a shared library with a C language API built using the
> cgo tools. There are many of C and C++ test programs and example programs as
> well in the project which need to link against the project shared library etc.
>
> Regards
> Bill Somerville.
>
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