Confusing syntax errors in C header when compiling Qt project

Hello,

I started working again at a Qt project and upgraded it from Qt 5.2.1 to 5.4. Now I get very confusing compiler errors, when I build this project in Qt Creator. The project uses a C library called "libnova" and the MinGW (GCC 4.9.x) compiler from Qt 5.4 finds one of its header files quite offending. I didn't experience this issue when I last worked on that project. Compiling with Qt 5.3 or 5.2.1 kit yield the same results.
I am using the latest libnova code, as I contributed some fixes for Windows. I compiled the library (as before) with MinGW via MSYS.

Here's the compiler output:

Code:

23:37:45: Running steps for project pyro...
23:37:45: Starting: "C:\Qt\Tools\mingw491_32\bin\mingw32-make.exe" clean
C:/Qt/Tools/mingw491_32/bin/mingw32-make -f Makefile.Debug clean
mingw32-make[1]: Entering directory 'D:/Andreas/Qt/build-pyro-Desktop_Qt_5_4_0_MinGW_32bit-Debug'
del debug\moc_mainwindow.cpp debug\moc_pyroengine.cpp debug\moc_imageanalysiswidget.cpp debug\moc_projectlistwidget.cpp debug\moc_skyobjectlistmodel.cpp debug\moc_miniatureoverlay.cpp debug\moc_imageloader.cpp
D:\Andreas\Qt\build-pyro-Desktop_Qt_5_4_0_MinGW_32bit-Debug\debug\moc_mainwindow.cpp konnte nicht gefunden werden
del ui_mainwindow.h ui_imageanalysiswidget.h ui_projectlistwidget.h
del debug\main.o debug\mainwindow.o debug\pyromath.o debug\testcases.o debug\pyroengine.o debug\imageanalysiswidget.o debug\projectlistwidget.o debug\skyobjectlistmodel.o debug\miniatureoverlay.o debug\imageloader.o debug\moc_mainwindow.o debug\moc_pyroengine.o debug\moc_imageanalysiswidget.o debug\moc_projectlistwidget.o debug\moc_skyobjectlistmodel.o debug\moc_miniatureoverlay.o debug\moc_imageloader.o
D:\Andreas\Qt\build-pyro-Desktop_Qt_5_4_0_MinGW_32bit-Debug\debug\main.o konnte nicht gefunden werden
mingw32-make[1]: Leaving directory 'D:/Andreas/Qt/build-pyro-Desktop_Qt_5_4_0_MinGW_32bit-Debug'
C:/Qt/Tools/mingw491_32/bin/mingw32-make -f Makefile.Release clean
mingw32-make[1]: Entering directory 'D:/Andreas/Qt/build-pyro-Desktop_Qt_5_4_0_MinGW_32bit-Debug'
del release\moc_mainwindow.cpp release\moc_pyroengine.cpp release\moc_imageanalysiswidget.cpp release\moc_projectlistwidget.cpp release\moc_skyobjectlistmodel.cpp release\moc_miniatureoverlay.cpp release\moc_imageloader.cpp
D:\Andreas\Qt\build-pyro-Desktop_Qt_5_4_0_MinGW_32bit-Debug\release\moc_mainwindow.cpp konnte nicht gefunden werden
del ui_mainwindow.h ui_imageanalysiswidget.h ui_projectlistwidget.h
D:\Andreas\Qt\build-pyro-Desktop_Qt_5_4_0_MinGW_32bit-Debug\ui_mainwindow.h konnte nicht gefunden werden
del release\main.o release\mainwindow.o release\pyromath.o release\testcases.o release\pyroengine.o release\imageanalysiswidget.o release\projectlistwidget.o release\skyobjectlistmodel.o release\miniatureoverlay.o release\imageloader.o release\moc_mainwindow.o release\moc_pyroengine.o release\moc_imageanalysiswidget.o release\moc_projectlistwidget.o release\moc_skyobjectlistmodel.o release\moc_miniatureoverlay.o release\moc_imageloader.o
D:\Andreas\Qt\build-pyro-Desktop_Qt_5_4_0_MinGW_32bit-Debug\release\main.o konnte nicht gefunden werden
mingw32-make[1]: Leaving directory 'D:/Andreas/Qt/build-pyro-Desktop_Qt_5_4_0_MinGW_32bit-Debug'
23:37:45: The process "C:\Qt\Tools\mingw491_32\bin\mingw32-make.exe" exited normally.
23:37:45: Configuration unchanged, skipping qmake step.
23:37:45: Starting: "C:\Qt\Tools\mingw491_32\bin\mingw32-make.exe" 
C:/Qt/Tools/mingw491_32/bin/mingw32-make -f Makefile.Debug
mingw32-make[1]: Entering directory 'D:/Andreas/Qt/build-pyro-Desktop_Qt_5_4_0_MinGW_32bit-Debug'
C:\Qt\5.4\mingw491_32\bin\uic.exe ..\pyro\mainwindow.ui -o ui_mainwindow.h
C:\Qt\5.4\mingw491_32\bin\uic.exe ..\pyro\imageanalysiswidget.ui -o ui_imageanalysiswidget.h
C:\Qt\5.4\mingw491_32\bin\uic.exe ..\pyro\projectlistwidget.ui -o ui_projectlistwidget.h
g++ -c -pipe -fno-keep-inline-dllexport -fopenmp -std=gnu++11 -g -frtti -Wall -Wextra -fexceptions -mthreads -DUNICODE -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -DQT_NEEDS_QMAIN -I..\pyro -I"..\..\..\Libraries\libnova-latest\src" -I"..\..\..\Libraries\Eigen3" -I"..\..\..\Libraries\ceres-solver-git\include" -I"..\..\..\Libraries\ceres-solver-git\internal\ceres\miniglog" -I"..\..\..\Libraries\ceres-solver-git\config" -I"C:\Qt\5.4\mingw491_32\include" -I"C:\Qt\5.4\mingw491_32\include\QtWidgets" -I"C:\Qt\5.4\mingw491_32\include\QtGui" -I"C:\Qt\5.4\mingw491_32\include\QtCore" -I"debug" -I"." -I"." -I"C:\Qt\5.4\mingw491_32\mkspecs\win32-g++" -o debug\main.o ..\pyro\main.cpp
In file included from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/i686-w64-mingw32/bits/gthr-default.h:35:0,
                 from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/i686-w64-mingw32/bits/gthr.h:148,
                 from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/ext/atomicity.h:35,
                 from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/bits/basic_string.h:39,
                 from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/string:52,
                 from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/random:40,
                 from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/bits/stl_algo.h:66,
                 from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/algorithm:62,
                 from C:\Qt\5.4\mingw491_32\include/QtCore/qglobal.h:81,
                 from C:\Qt\5.4\mingw491_32\include/QtCore/qcoreapplication.h:37,
                 from C:\Qt\5.4\mingw491_32\include\QtWidgets/qapplication.h:37,
                 from C:\Qt\5.4\mingw491_32\include\QtWidgets/QApplication:1,
                 from ..\pyro\main.cpp:1:
..\..\..\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected unqualified-id before '{' token
 struct tm *gmtime_r (time_t *t, struct tm *gmt);
            ^
..\..\..\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected ')' before '{' token
..\..\..\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected primary-expression before 'struct'
 struct tm *gmtime_r (time_t *t, struct tm *gmt);
            ^
..\..\..\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected '}' before 'struct'
..\..\..\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected constructor, destructor, or type conversion before ';' token
 struct tm *gmtime_r (time_t *t, struct tm *gmt);
            ^
..\..\..\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: '___tmp_tm' does not name a type
 struct tm *gmtime_r (time_t *t, struct tm *gmt);
            ^
..\..\..\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected unqualified-id before 'if'
 struct tm *gmtime_r (time_t *t, struct tm *gmt);
            ^
..\..\..\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: '___tmp_tm' does not name a type
 struct tm *gmtime_r (time_t *t, struct tm *gmt);
            ^
..\..\..\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected unqualified-id before ')' token
 struct tm *gmtime_r (time_t *t, struct tm *gmt);
            ^
In file included from ..\..\..\Libraries\libnova-latest\src/libnova/libnova.h:127:0,
                 from ..\pyro\pyromath.h:6,
                 from ..\pyro\pyroengine.h:16,
                 from ..\pyro\mainwindow.h:10,
                 from ..\pyro\main.cpp:3:
..\..\..\Libraries\libnova-latest\src/libnova/utility.h:258:1: error: expected declaration before '}' token
 };
 ^
Makefile.Debug:2583: recipe for target 'debug/main.o' failed
mingw32-make[1]: *** [debug/main.o] Error 1
mingw32-make[1]: Leaving directory 'D:/Andreas/Qt/build-pyro-Desktop_Qt_5_4_0_MinGW_32bit-Debug'
mingw32-make: *** [debug] Error 2
makefile:34: recipe for target 'debug' failed
23:37:48: The process "C:\Qt\Tools\mingw491_32\bin\mingw32-make.exe" exited with code 2.
Error while building/deploying project pyro (kit: Desktop Qt 5.4.0 MinGW 32bit)
When executing step "Make"
23:37:48: Elapsed time: 00:03.

You can see the libnova's header file "utility.h" here: http://sourceforge.net/p/libnova/lib...nova/utility.h

Honestly, I don't understand the compilers complaints. Most of the error messages do not seem to be related to the line declaring the gmtime_r() function. Can someone help, please?

Andreas

Re: Confusing syntax errors in C header when compiling Qt project

Okay, I've got something here.

The compiler errors are only about those gmtime_r and strtok_r declarations. I just commented out these two declarations in <utility.h> and built my project again. It compiles without errors. Apparently, the C library now defines these two functions.

Digging a little deeper into <time.h> from the toolchain bundled with Qt, I found this for gmtime_r:
Code:

#ifndef gmtime_r #define gmtime_r(_Time,_Tm) ...
<pthread.h> contains the same thing for strtok_r. Was this added to the C library recently?

Re: Confusing syntax errors in C header when compiling Qt project

Update:

This small example can also reproduce these compiler errors:

Code:

#include <iostream>
#include <libnova/utiltiy.h>
 
int main() { return 0; }

Errors occure, because <iostream> also includes <pthread.h> somewhere down the road. And <pthread.h> has this funny stuff in it:

Code:

#undef gmtime_r
#define gmtime_r(_Time,_Tm)     ({ struct tm *___tmp_tm;                \
                                                pthread_testcancel();   \
                                                ___tmp_tm = gmtime((_Time)); \
                                                if (___tmp_tm) {        \
                                                  *(_Tm) = *___tmp_tm;  \
                                                  ___tmp_tm = (_Tm);    \
                                                }                       \
                                                ___tmp_tm;      })

Then comes <libnova/utility.h> and declares:

Code:

struct tm *gmtime_r (time_t *t, struct tm *gmt);

When I include <libnova/utility.h> first, it will compile sucessfully. But being forced to include headers in a specific order feels very wrong. At least in this case. And it may not be possible in a very big project.

Is this a bug in the C library provided with MinGW?
What's the best way to handle this? For the time being, I could surround the conflicting declaratioin in <libnova/utility.h> with #ifndef...#endif.

Any advice?

Re: Confusing syntax errors in C header when compiling Qt project

Quote:

Originally Posted by antimatter

Any advice?

Reverse the order of includes.

Never touch any header files outside your project, fix problems in your code instead.