Trouble configuring qt - can't find function _popen

vega

Hello,

I'm trying to build stellarium from source but I've run into a problem configuring qt. When I try and run the configure.bat script, I get the following errors:

C:/qt5/qtbase/qmake/library/qmakebuiltins.cpp: In member function 'QByteArray QMakeEvaluator::getCommandOutput(const QString&, int*) const':
C:/qt5/qtbase/qmake/library/qmakebuiltins.cpp:76:18: error: '_popen' was not declared in this scope; did you mean '_lopen'?
   76 | #define QT_POPEN _popen
      |                  ^~~~~~

C:/qt5/qtbase/qmake/library/qmakebuiltins.cpp:540:22: note: in expansion of macro 'QT_POPEN'
  540 |     if (FILE *proc = QT_POPEN(QString(QLatin1String("cd ")
      |                      ^~~~~~~~

C:/qt5/qtbase/qmake/library/qmakebuiltins.cpp:78:19: error: '_pclose' was not declared in this scope; did you mean '_lclose'?
   78 | #define QT_PCLOSE _pclose
      |                   ^~~~~~~

C:/qt5/qtbase/qmake/library/qmakebuiltins.cpp:550:18: note: in expansion of macro 'QT_PCLOSE'
  550 |         int ec = QT_PCLOSE(proc);
      |                  ^~~~~~~~~

C:/qt5/qtbase/qmake/library/qmakebuiltins.cpp: In member function 'QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateBuiltinExpand(const QMakeInternal::QMakeBuiltin&, const ProKey&, const ProStringList&, ProStringList&)':
C:/qt5/qtbase/qmake/library/qmakebuiltins.cpp:1241:25: error: 'KEY_WOW64_32KEY' was not declared in this scope
 1241 |                 flags = KEY_WOW64_32KEY;
      |                         ^~~~~~~~~~~~~~~

C:/qt5/qtbase/qmake/library/qmakebuiltins.cpp:1244:25: error: 'KEY_WOW64_64KEY' was not declared in this scope
 1244 |                 flags = KEY_WOW64_64KEY;
      |                         ^~~~~~~~~~~~~~~

Makefile:255: recipe for target 'qmakebuiltins.o' failed
mingw32-make: *** [qmakebuiltins.o] Error 1

While all the errors are an issue, I'm mainly concerned about the _popen one. Both windows.h and stdio.h have been #include'd, and I even upgraded my mingw install to try and fix the error, but not luck.

Has anyone encountered anything like this in their build/ know who to fix it?

Thanks

jsulm

@vega Do you use the MinGW console to compile (you will find it in Qt menu in Windows start menu)?
What exact MinGW version do you use?

JonB

@vega
I know nothing about MinGW. But _popen() etc. are "low-level" OS calls. Supplied under Linux, seems to be there from MSVC. But not necessarily MinGW. See e.g. https://stackoverflow.com/questions/46343789/cant-find-popen-and-pclose-with-windows-codeblocks-mingw-16-01, https://stackoverflow.com/questions/22166633/mingw-function-not-found-when-compiled-with-std-c11, https://github.com/boostorg/type_erasure/issues/16 for others reporting problem on _popen under MinGW.

vega

@jsulm It looks like I'm using MinGW version 7 - the exact install is mingw-w64-v7.0.0. I tried to compile it directly from the command line in VS code. I can't seem to see the Qt menu in my Windows start menu - is there another way to access it?

Christian Ehrlicher

I'm pretty sure you've msys in your PATH and therefore configure is picking up the wrong compiler.

vega

@Christian-Ehrlicher It looks like I have both MinGW and msvs2017 (from qt) in my PATH. Should I removed MinGW?

Christian Ehrlicher

It depends on what you want to sue to compile Qt - MSVC or MinGW - only one of them should be visible to configure when compiling Qt.
Why do you want to compile Qt at all?

vega

@Christian-Ehrlicher I'm building Stellarium from source, and I need Qt in order to do so.

vega

@Christian-Ehrlicher Also, when I try and combile with just MinGW in path, I get the same error. When I try and compile with just msvc, I get an error that says "Cannot detect host toolchain. Please use -platform. Aborting."

vega

Note to future visitors: I was unfortunately unable to fix the _popen error. I eventually just decided to download qt with the qt installer ( it wasn't working for me previously) and it seems to be ok now. If anyone else encounters this error, good luck!

yasamson

It is necessary to change the mingw version according to the table https://wiki.qt.io/MinGW.