Building Qt with QT_DISABLE_DEPRECATED_UP_TO set fails

[l3u_]

Hi all,

https://doc.qt.io/qt-6/qtdeprecationmarkers.html#QT_DISABLE_DEPRECATED_UP_TO states: "If you also build Qt for yourself, including this define in your build configuration for Qt will make your binaries smaller by leaving out even the implementation of the deprecated APIs".

I just tried, having exported CXXFLAGS="-DQT_DISABLE_DEPRECATED_UP_TO=0x060500". But using this, the Qt build itself fails:

FAILED: src/corelib/CMakeFiles/Core.dir/global/qglobal.cpp.o 
/usr/bin/c++ -DBACKTRACE_HEADER=\"execinfo.h\" -DPCRE2_CODE_UNIT_WIDTH=16 -DQT_ASCII_CAST_WARNINGS -DQT_BUILDING_QT -DQT_BUILD_CORE_LIB -DQT_DEPRECATED_WARNINGS -DQT_EXPLICIT_QFILE_CONSTRUCTION_FROM_PATH -DQT_LEAN_HEADERS=1 -DQT_MOC_COMPAT -DQT_NO_CAST_TO_ASCII -DQT_NO_CONTEXTLESS_CONNECT -DQT_NO_DEBUG -DQT_NO_FOREACH -DQT_NO_JAVA_STYLE_ITERATORS -DQT_NO_NARROWING_CONVERSIONS_IN_CONNECT -DQT_NO_QASCONST -DQT_NO_QEXCHANGE -DQT_NO_QPAIR -DQT_NO_QSNPRINTF -DQT_NO_STD_FORMAT_SUPPORT -DQT_NO_USING_NAMESPACE -DQT_TYPESAFE_FLAGS -DQT_USE_NODISCARD_FILE_OPEN -DQT_USE_QSTRINGBUILDER -D_GLIBCXX_ASSERTIONS -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/Core_autogen/include -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/include -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/include/QtCore -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/src/corelib -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/global -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/kernel -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/src/corelib/../3rdparty/tinycbor/src -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/include/QtCore/6.9.2 -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/include/QtCore/6.9.2/QtCore -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/src/corelib/../3rdparty/double-conversion/double-conversion -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/src/corelib/../3rdparty/double-conversion -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/src/corelib/../3rdparty/forkfd -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/.rcc -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/mkspecs/linux-g++ -I/home/tobias/Qt/qtbase-everywhere-src-6.9.2/src/3rdparty/pcre2/src -DQT_DISABLE_DEPRECATED_UP_TO=0x060500 -DNDEBUG -Os -fPIC -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -ffunction-sections -fdata-sections -U_FORTIFY_SOURCE -Wsuggest-override -fcf-protection=full -D_FORTIFY_SOURCE=2 -fstack-protector-strong -fstack-clash-protection -fexceptions -std=gnu++17 -ftemplate-depth=2048 -Winvalid-pch -include /home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/CMakeFiles/Core.dir/cmake_pch.hxx -MD -MT src/corelib/CMakeFiles/Core.dir/global/qglobal.cpp.o -MF src/corelib/CMakeFiles/Core.dir/global/qglobal.cpp.o.d -o src/corelib/CMakeFiles/Core.dir/global/qglobal.cpp.o -c /home/tobias/Qt/qtbase-everywhere-src-6.9.2/src/corelib/global/qglobal.cpp
In file included from /home/tobias/Qt/qtbase-everywhere-src-6.9.2/src/corelib/global/qglobal.cpp:378:
/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/Core_autogen/include/moc_qnamespace.cpp: In function ‘constexpr auto Qt::qt_create_metaobjectdata() [with <template-parameter-1-1> = {anonymous}::qt_meta_tag_ZN2QtE_t]’:
/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/Core_autogen/include/moc_qnamespace.cpp:1673:43: error: ‘AA_UseHighDpiPixmaps’ is not a member of ‘Qt::ApplicationAttribute’
1673 |             {  299, ApplicationAttribute::AA_UseHighDpiPixmaps },
    |                                           ^~~~~~~~~~~~~~~~~~~~
/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/Core_autogen/include/moc_qnamespace.cpp:1680:43: error: ‘AA_EnableHighDpiScaling’ is not a member of ‘Qt::ApplicationAttribute’
1680 |             {  306, ApplicationAttribute::AA_EnableHighDpiScaling },
    |                                           ^~~~~~~~~~~~~~~~~~~~~~~
/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/Core_autogen/include/moc_qnamespace.cpp:1681:43: error: ‘AA_DisableHighDpiScaling’ is not a member of ‘Qt::ApplicationAttribute’
1681 |             {  307, ApplicationAttribute::AA_DisableHighDpiScaling },
    |                                           ^~~~~~~~~~~~~~~~~~~~~~~~
/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/Core_autogen/include/moc_qnamespace.cpp:1660:85: error: cannot convert ‘<brace-enclosed initializer list>’ to ‘const QtMocHelpers::EnumData<Qt::ApplicationAttribute>::EnumEntry (&)[31]’
1660 |         QtMocHelpers::EnumData<ApplicationAttribute>(286, 286, QMC::EnumFlags{}).add({
    |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~
1661 |             {  287, ApplicationAttribute::AA_QtQuickUseDefaultSizePolicy },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~          
1662 |             {  288, ApplicationAttribute::AA_DontShowIconsInMenus },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                 
1663 |             {  289, ApplicationAttribute::AA_NativeWindows },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                        
1664 |             {  290, ApplicationAttribute::AA_DontCreateNativeWidgetSiblings },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~       
1665 |             {  291, ApplicationAttribute::AA_PluginApplication },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                    
1666 |             {  292, ApplicationAttribute::AA_DontUseNativeMenuBar },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                 
1667 |             {  293, ApplicationAttribute::AA_MacDontSwapCtrlAndMeta },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~               
1668 |             {  294, ApplicationAttribute::AA_Use96Dpi },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                             
1669 |             {  295, ApplicationAttribute::AA_DisableNativeVirtualKeyboard },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~         
1670 |             {  296, ApplicationAttribute::AA_DontUseNativeMenuWindows },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~             
1671 |             {  297, ApplicationAttribute::AA_SynthesizeTouchForUnhandledMouseEvents },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1672 |             {  298, ApplicationAttribute::AA_SynthesizeMouseForUnhandledTouchEvents },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1673 |             {  299, ApplicationAttribute::AA_UseHighDpiPixmaps },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                    
1674 |             {  300, ApplicationAttribute::AA_ForceRasterWidgets },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                   
1675 |             {  301, ApplicationAttribute::AA_UseDesktopOpenGL },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                     
1676 |             {  302, ApplicationAttribute::AA_UseOpenGLES },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                          
1677 |             {  303, ApplicationAttribute::AA_UseSoftwareOpenGL },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                    
1678 |             {  304, ApplicationAttribute::AA_ShareOpenGLContexts },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                  
1679 |             {  305, ApplicationAttribute::AA_SetPalette },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                           
1680 |             {  306, ApplicationAttribute::AA_EnableHighDpiScaling },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                 
1681 |             {  307, ApplicationAttribute::AA_DisableHighDpiScaling },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                
1682 |             {  308, ApplicationAttribute::AA_UseStyleSheetPropagationInWidgetStyles },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1683 |             {  309, ApplicationAttribute::AA_DontUseNativeDialogs },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                 
1684 |             {  310, ApplicationAttribute::AA_SynthesizeMouseForUnhandledTabletEvents },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1685 |             {  311, ApplicationAttribute::AA_CompressHighFrequencyEvents },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~          
1686 |             {  312, ApplicationAttribute::AA_DontCheckOpenGLContextThreadAffinity },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 
1687 |             {  313, ApplicationAttribute::AA_DisableShaderDiskCache },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~               
1688 |             {  314, ApplicationAttribute::AA_DontShowShortcutsInContextMenus },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~      
1689 |             {  315, ApplicationAttribute::AA_CompressTabletEvents },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                 
1690 |             {  316, ApplicationAttribute::AA_DisableSessionManager },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                
1691 |             {  317, ApplicationAttribute::AA_AttributeCount },
    |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                       
1692 |         }),
    |         ~~                                                                           
In file included from /home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/include/QtCore/qtmochelpers.h:1,
                from /home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/Core_autogen/include/moc_qnamespace.cpp:13,
                from /home/tobias/Qt/qtbase-everywhere-src-6.9.2/src/corelib/global/qglobal.cpp:378:
/home/tobias/Qt/qtbase-everywhere-src-6.9.2/src/corelib/kernel/qtmochelpers.h:335:63: note:   initializing argument 1 of ‘constexpr auto QtMocHelpers::EnumData<Enum, N>::add(const QtMocHelpers::EnumData<Enum, N>::EnumEntry (&)[Added]) const [with int Added = 31; Enum = Qt::ApplicationAttribute; int N = 0]’
335 |     template <int Added> constexpr auto add(const EnumEntry (&entries)[Added]) const
    |                                             ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
In file included from /home/tobias/Qt/qtbase-everywhere-src-6.9.2/src/corelib/global/qglobal.cpp:378:
/home/tobias/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/Core_autogen/include/moc_qnamespace.cpp:38:35: error: invalid return type ‘auto’ of ‘constexpr’ function ‘constexpr auto Qt::qt_create_metaobjectdata() [with <template-parameter-1-1> = {anonymous}::qt_meta_tag_ZN2QtE_t]’
38 | template <> constexpr inline auto Qt::qt_create_metaobjectdata<qt_meta_tag_ZN2QtE_t>()
    |                                   ^~
[13/1026] Building CXX object src/corelib/CMakeFiles/Core.dir/kernel/qcoreapplication.cpp.o

Seems like the deprecated AA_EnableHighDpiScaling (deprecated in 6.0.0 iirc) was removed – as requested – but it's nevertheless still used by Qt itself?!

What do I do wrong?

[Christian Ehrlicher]

This flag is not meant for building Qt, just for your lib.

[l3u_]

But the docs tell me to use it for my own Qt build?!

[Christian Ehrlicher]

Where in the docs?

[l3u_]

@l3u_ said in Building Qt with QT_DISABLE_DEPRECATED_UP_TO set fails:

https://doc.qt.io/qt-6/qtdeprecationmarkers.html#QT_DISABLE_DEPRECATED_UP_TO states: "If you also build Qt for yourself, including this define in your build configuration for Qt will make your binaries smaller by leaving out even the implementation of the deprecated APIs".

[Christian Ehrlicher]

I missed this sentence, sorry.

You should start over with a clean build dir - it works fine here (on windows, but this does not affect moc output wrt this topic). I can't see AA_EnableHighDpiScaling anywhere in the generated files.
Also make sure the correct moc executable is picked for generation - look in the header to see at least the version of the moc executable which created the file.

[l3u_]

My initial attempt was in a Ubuntu 22 LTS QEMU VM. I just tried in a naked Windows 10 VM, installed MinGW, CMake and Ninja using Qt's online installer, downloaded the qtbase sources for Qt 6.9.2, and did set CXXFLAGS=-DQT_DISABLE_DEPRECATED_UP_TO=0x060500.

Very same result as on Ubuntu:

FAILED: src/corelib/CMakeFiles/Core.dir/global/qglobal.cpp.obj
...
In file included from C:/Qt/qtbase-everywhere-src-6.9.2/src/corelib/global/qglobal.cpp:378:
C:/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/Core_autogen/include/moc_qnamespace.cpp: In functi
on 'constexpr auto Qt::qt_create_metaobjectdata() [with <template-parameter-1-1> = {anonymous}::qt_met
a_tag_ZN2QtE_t]':
C:/Qt/qtbase-everywhere-src-6.9.2/build/src/corelib/Core_autogen/include/moc_qnamespace.cpp:1673:43: e
rror: 'AA_UseHighDpiPixmaps' is not a member of 'Qt::ApplicationAttribute'
1673 |             {  299, ApplicationAttribute::AA_UseHighDpiPixmaps },
    |                                           ^~~~~~~~~~~~~~~~~~~~
...

And here, there's no chance that some system-widely installed moc has been used, as there's none …

[l3u_]

My configure statement was:

..\configure ^
    -release ^
    -static ^
    -optimize-size ^
    -prefix C:\Qt\6.9.2_static ^
    ^
    -no-feature-androiddeployqt ^
    -no-feature-macdeployqt ^
    -no-feature-concurrent ^
    -no-feature-dbus ^
    -no-feature-printsupport ^
    -no-feature-testlib ^
    -no-feature-textmarkdownreader ^
    -no-feature-textmarkdownwriter ^
    -no-feature-textodfwriter ^
    -no-feature-xml ^
    ^
    -no-opengl ^
    -no-gif ^
    -no-ico ^
    -qt-libjpeg ^
    -qt-libpng ^
    ^
    -no-sql-odbc ^
    -no-sql-mysql ^
    -qt-sqlite

[Christian Ehrlicher]

Your configure statement does not contain ´-DQT_DISABLE_DEPRECATED_UP_TO=0x060500´ ...

[l3u_]

Just read the post (where I describe the build system I use) … I exported it as an environment variable. And apparently, it was actually picked up – otherwise, the build would not fail.

Just try it – it's 100% reproducible …

[Christian Ehrlicher]

Even the compiler picks this up, moc does not...

[l3u_]

Appending -- -DQT_DISABLE_DEPRECATED_UP_TO=0x060500 to the configure call instead of setting it as an environment variable did the trick. Thanks :-)

[SGaist]

@l3u_ hi,

Because it's not an environment variable it's a define.

[l3u_]

Some small hints about the correct approach about this in the docs would be very nice 😅 – at least for clueless end-users like me …

[SGaist]

There is also the -disable-deprecated-up-to configure option (just discovered while checking Qt's sources).

You can open a ticket on the bug tracking system for the documentation to be improved. Even better, you can also submit a patch to make the improvement yourself (highly appreciated) :-)

[l3u_]

Mentioning that switch would be even better! I'll see if I can find a reasonable wording and file a bug with a patch!

[Christian Ehrlicher]

configure --help:

You can pass CMake variables as configure arguments:
    configure VAR=value
which is equivalent to
    configure -- -DVAR=value