[cmake-developers] [CMake 0014654]: mingw -isystem flag c header float.h conflict

Mantis Bug Tracker mantis at public.kitware.com
Mon Dec 16 14:28:52 EST 2013


The following issue has been SUBMITTED. 
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http://www.cmake.org/Bug/view.php?id=14654 
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Reported By:                jschueller
Assigned To:                
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Project:                    CMake
Issue ID:                   14654
Category:                   CMake
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     new
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Date Submitted:             2013-12-16 14:28 EST
Last Modified:              2013-12-16 14:28 EST
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Summary:                    mingw -isystem flag c header float.h conflict
Description: 
When including the UseQt4 module combined with cross-compiling with mingw64,
cmake uses these includes (read in the .rsp file):
-isystem /usr/i686-w64-mingw32/include -isystem
/usr/i686-w64-mingw32/include/QtGui -isystem
/usr/i686-w64-mingw32/include/QtCore

... which prevent from using defines like DBL_EPSILON in float.h:
/usr/bin/i686-w64-mingw32-g++   -DQT_CORE_LIB -DQT_GUI_LIB -DQT_NO_DEBUG
@CMakeFiles/main.dir/includes_CXX.rsp   -o CMakeFiles/main.dir/main.cxx.obj -c
.../main.cxx
...
error: ‘DBL_EPSILON’ was not declared in this scope

If I remove the -isystem flag, it builds fine.
The -isytem seems to come from 
/usr/share/cmake-2.8/Modules/Compiler/GNU.cmake:55:   
set(CMAKE_INCLUDE_SYSTEM_FLAG_${lang} "-isystem ")



Steps to Reproduce: 

The minimal cmakelist using useqt4:

cmake_minimum_required ( VERSION 2.8 )
project ( mingw-test CXX )
find_package ( Qt4 REQUIRED QtCore)
include ( ${QT_USE_FILE} )
add_executable(main main.cxx)

Define a main.cxx:

#include <iostream>
#include "float.h"

int main( int argc, char **argv )
{
  std::cout <<DBL_EPSILON<<std::endl;
  return 0;
}


Also non-working from c:
#include <stdio.h>
#include <float.h>

int main() {
printf("%g", FLT_EPSILON);
return 0;
}

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Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2013-12-16 14:28 jschueller     New Issue                                    
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