Hi everyone,
any feedback on this?
As a summary, it's about adding the default include paths of GCC to the
variables "CMAKE_*_IMPLICIT_INCLUDE_DIRECTORIES" to avoid CMake modules
or scripts to mess up with them, more specifically with their order.
Cheers,
Olivier
On 2018-11-3 21:41, Olivier Croquette wrote:
Hi,
I got recently build errors when introducing external dependencies in
my project, the reason is that those components re-add standard SYSTEM
include search paths, which changes the search order and causes
#include_next to fail. The typical error message is:
|C:\...\lib\gcc\x86_64-w64-mingw32\7.2.0\include\c++\cstdlib:75:
error: stdlib.h: No such file or directory|
|at #include_next
|
|
|
||
The following bug report against GCC describes the same issue
independently of CMake, and apparently no improvement is to be
expected from the compiler itself:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70129
So I rolled up my sleeves and implemented the following solution in
CMake. It calls the preprocessor to get the standard include search
paths and adds them to CMAKE_C_IMPLICIT_INCLUDE_DIRECTORIES and
CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES.
When a project or an external component tries to add them, CMake
ignores this, and the search order stays unharmed.
if("${CMAKE_MINGW_IMPLICIT_INCLUDE_DIRECTORIES}" STREQUAL "")
# Run the preprocessor in verbose mode on an empty input
execute_process(
COMMAND
"${CMAKE_CXX_COMPILER}"
"-E"
"-Wp,-v"
"-"
INPUT_FILE "NUL" # Special Windows file, equivalent to /dev/null
OUTPUT_VARIABLE _mingw_cpp_out # Capture stdout
ERROR_VARIABLE _mingw_cpp_error # Capture stderr
)
# Create list of lines from stderr output:
string(REGEX REPLACE ";" "\\\\;" _mingw_cpp_error
"${_mingw_cpp_error}")
string(REGEX REPLACE "\n" ";" _mingw_cpp_error "${_mingw_cpp_error}")
# Look for this text block and gather the paths:
# #include search starts here:
# C:/..../bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/include
# C:/..../bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/include-fixed
#
C:/..../bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/include
# End of search list.
set(_mingw_cpp_list)
foreach(_mingw_cpp_line ${_mingw_cpp_error})
if("${_mingw_cpp_line}" MATCHES "#include search starts here:")
# Block starts
set(_mingw_cpp_state "ON")
elseif("${_mingw_cpp_line}" MATCHES "End of search list.")
# Block ends
set(_mingw_cpp_state "OFF")
elseif("${_mingw_cpp_state}")
# Within block
# Clean up and beautify the path
string(STRIP "${_mingw_cpp_line}" _mingw_cpp_line)
get_filename_component(_mingw_cpp_line ${_mingw_cpp_line}
REALPATH)
list(APPEND _mingw_cpp_list ${_mingw_cpp_line})
endif()
endforeach()
# Set the list in the cache, so that we don't have to run the
external process again
set(CMAKE_MINGW_IMPLICIT_INCLUDE_DIRECTORIES ${_mingw_cpp_list}
CACHE INTERNAL "List of MinGW system include paths")
endif()
list(APPEND CMAKE_C_IMPLICIT_INCLUDE_DIRECTORIES
${CMAKE_MINGW_IMPLICIT_INCLUDE_DIRECTORIES})
list(APPEND CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES
${CMAKE_MINGW_IMPLICIT_INCLUDE_DIRECTORIES})
My question is: shouldn't this be done within the standard CMake
distribution, when using any GCC based compiler?
Olivier
--
Powered by www.kitware.com
Please keep messages on-topic and check the CMake FAQ at:
http://www.cmake.org/Wiki/CMake_FAQ
Kitware offers various services to support the CMake community. For more
information on each offering, please visit:
CMake Support: http://cmake.org/cmake/help/support.html
CMake Consulting: http://cmake.org/cmake/help/consulting.html
CMake Training Courses: http://cmake.org/cmake/help/training.html
Visit other Kitware open-source projects at
http://www.kitware.com/opensource/opensource.html
Follow this link to subscribe/unsubscribe:
https://cmake.org/mailman/listinfo/cmake
