MantisBT - CMake
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ID	Project	Category	View Status	Date Submitted	Last Update
0015045	CMake	Modules	public	2014-07-29 07:42	2016-06-10 14:31

Reporter	Nils Gladitz
Assigned To	James Bigler
Priority	normal	Severity	minor	Reproducibility	always
Status	closed	Resolution	moved
Platform		OS		OS Version
Product Version	CMake 3.0
Target Version		Fixed in Version

Summary	0015045: FindCUDA.cmake passes directory COMPILE_DEFINITIONS to nvcc without handling generator expressions
Description	A colleague noticed this while using UseQt4.cmake which since 3.0 contains: set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS $<$<NOT:$<CONFIG:Debug>>:QT_NO_DEBUG>) To recreate the old behaviour generator expressions could be stripped with the new string(GENEX_STRIP) or perhaps even expanded with file(GENERATE).
Steps To Reproduce	cmake_minimum_required(VERSION 3.0) set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS $<$<NOT:$<CONFIG:Foo>>:NOT_FOO> ) find_package(CUDA REQUIRED) cuda_add_library(empty empty.cu)
Additional Information
Tags	No tags attached.
Relationships
Attached Files	FindCUDA.tar.gz (25,176) 2016-02-29 04:57 https://public.kitware.com/Bug/file/5635/FindCUDA.tar.gz

Issue History
Date Modified	Username	Field	Change
2014-07-29 07:42	Nils Gladitz	New Issue
2014-07-29 07:42	Nils Gladitz	Status	new => assigned
2014-07-29 07:42	Nils Gladitz	Assigned To	=> James Bigler
2016-02-29 04:57	Benoît Bleuzé	Note Added: 0040577
2016-02-29 04:57	Benoît Bleuzé	File Added: FindCUDA.tar.gz
2016-02-29 09:31	Benoît Bleuzé	Note Edited: 0040577	bug_revision_view_page.php?bugnote_id=40577#r2045
2016-03-04 05:04	Giovanni Funchal	Note Added: 0040595
2016-03-11 08:03	Benoît Bleuzé	Note Added: 0040661
2016-03-11 09:08	Giovanni Funchal	Note Added: 0040663
2016-06-10 14:29	Kitware Robot	Note Added: 0042595
2016-06-10 14:29	Kitware Robot	Status	assigned => resolved
2016-06-10 14:29	Kitware Robot	Resolution	open => moved
2016-06-10 14:31	Kitware Robot	Status	resolved => closed

Notes

Hi Nils,

I am struggling with the same problem. I have implemented what I deem an ugly solution, that works for me, but I would like the opinion of the cmake developers on the proper way to solve the issue.

Here is my temporary solution (attached are all the files needed to get FindCuda working).

Let me explain the problem, and the fix.

The original FindCUDA script runs configure() on a cmake script that just copies a list of definitions and flags. To do that it gets the list of definitions from the directory property, and adds -D to each of them, and then adds them to a single variable ${nvcc_flags}.

This cmake script is then executed by a custom command at build time.

The problem, as you described, is that definitions can contain generator expressions, and those are just copied as-is to that configured cmake script.

My fix does what you suggested: after the configure step I run file(GENERATE) and create configuration specific cmake scripts. the custom_command then runs the configuration specific cmake script using in turn a generator expression for the configuration.

However, this is not sufficient, as the ${nvcc_flags} variable copies definitions after having put a "-D" in front of each of them. If the generator expression results in an empty string, let's say -totally randomly-: $<$<NOT:$<CONFIG:Debug>>:QT_NO_DEBUG>, then the generated file ends up having things like "-D -D SOME_VAR", and the compilation spews warnings all over the place about no identifiers for definitions.

To fix this, I also patched the script "run_nvcc.cmake", and here the hack becomes plain ugly:

set(nvcc_flags_tmp @nvcc_flags@) # list
foreach(flag IN LISTS nvccflags_tmp)
    if(NOT "${flag}" STREQ "-D" )
        list(APPEND nvcc_flags ${flag})
    endif()
endforeach()

I fix the list of flags in the generated file at build time.

This works fine, but is not really easy to maintain or easy to read.

Is there anyone who worked on this, or who is ready to suggest other ways to fix it?

I have one or two ideas, such as separating the list of definition to the rest of the nvcc_flags as long as possible and only add the "-D" in the run_nvcc.cmake script, which would make things a bit more readable, but maybe there are other places where generator expressions could lurk, and here is where I need the most your input.

Ben.

Hi Giovanni,

The directory property INCLUDE_DIRECTORIES is passed to run_nvcc.cmake at configuration time through a variable called ${CUDA_NVCC_INCLUDE_ARGS}. I didn't think about the target property INCLUDE_DIRECTORIES or the directory one, but you are experiencing a happy side effect of calling file(GENERATE). Every bit of text in the ${custom_target_script} that looks like a generator expression will be replaced then.

Similar things are done in the Qt4Macros.cmake, but there the script also works for the target include properties(see https://cmake.org/gitweb?p=cmake.git;a=blob;f=Modules/Qt4Macros.cmake;h=7d7f5aa411f9be3761de6ffd6ec6de2d2a77a417;hb=9ce60ff5 [^]):

if(moc_target)
     list(APPEND targetincludes "$<TARGET_PROPERTY:${moc_target},INCLUDE_DIRECTORIES>")
     list(APPEND targetdefines "$<TARGET_PROPERTY:${moc_target},COMPILE_DEFINITIONS>")

     set(targetincludes "$<$<BOOL:${targetincludes}>:-I$<JOIN:${targetincludes},\n-I>\n>")
     set(targetdefines "$<$<BOOL:${targetdefines}>:-D$<JOIN:${targetdefines},\n-D>\n>")

     file (GENERATE
       OUTPUT ${_moc_parameters_file}
       CONTENT "${targetdefines}${targetincludes}${targetoptions}${_moc_parameters}\n"
       CONDITION 1
     )

     set(targetincludes)
     set(targetdefines)
   else()
     file(WRITE ${_moc_parameters_file} "${_moc_parameters}\n")
   endif()

   set(_moc_extra_parameters_file @${_moc_parameters_file})
   add_custom_command(OUTPUT ${outfile}
                       COMMAND ${QT_MOC_EXECUTABLE} ${_moc_extra_parameters_file}
                       DEPENDS ${infile}
                       ${_moc_working_dir}
                       VERBATIM)

I guess here something similar should be done, parsing the definitions to a variable before putting them in the generated file, and parsing target and directory include properties
at that same time, to a variable, and then calling file(GENERATE).

Problem: are there other properties to take care of we have forgotten?

I see :
* INCLUDE_DIRECTORIES
* COMPILE_DEFINITIONS
* COMPILE_FLAGS
* COMPILE_OPTIONS
* ??? Anything else?