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cmake: fix finding Qt private headers with Qt >=6.10#53

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cmake: fix finding Qt private headers with Qt >=6.10#53
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whitslack:fix-private-headers

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@whitslack whitslack commented Jan 16, 2026

Qt private header directories only get added to the include search path when the Qt6::${component}Private library is added to the target.

@whitslack whitslack force-pushed the fix-private-headers branch 2 times, most recently from 2cf6add to 5420bec Compare January 16, 2026 10:11
whitslack referenced this pull request in Tatsh/tatsh-overlay Jan 17, 2026
@Tatsh
dev-qt/qtwebkit: hacky fix for building against 6.10
8535bf8 
Signed-off-by: Andrew Udvare <audvare@gmail.com>
@whitslack whitslack marked this pull request as ready for review January 17, 2026 10:46
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Tatsh commented Jan 17, 2026

This gets past the configure stage and gets 99% into the build but fails for me:

webkit-1ab4d21d082e89fe1837c0279467a6da18c78cf0/Tools/QtTestBrowser/launcherwindow.h:47:10: fatal error: private/qeventpoint_p.h: No such file or directory
   47 | #include <private/qeventpoint_p.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~

This file does exist for me at /usr/include/qt6/QtGui/6.10.1/QtGui/private/qeventpoint_p.h but I am assuming the include path is not being set properly.

The command has these -isystem flags:

-isystem /usr/include/qt6/QtGui \
-isystem /usr/include/qt6 \
-isystem /usr/include/qt6/QtCore \
-isystem /usr/include/qt6/QtDBus \
-isystem /usr/include/qt6/QtNetwork \
-isystem /usr/include/qt6/QtWidgets \
-isystem /usr/lib64/qt6/mkspecs/linux-g++ \
-isystem /usr/include/qt6/QtPrintSupport \

All of the -I flags are only referencing directories in the source.

-isystem /usr/include/qt6/QtGui/6.10.1/QtGui \
-isystem /usr/include/qt6/QtGui/6.10.1 \
-isystem /usr/include/qt6/QtCore/6.10.1 \

If I run this manually with the above added, it compiles that file.

Tatsh added a commit to Tatsh/tatsh-overlay that referenced this pull request Jan 17, 2026
@Tatsh
dev-qt/qtwebkit: better fixes for building against Qt 6.10
29bcca5 
Related-to: movableink/webkit#53
Signed-off-by: Andrew Udvare <audvare@gmail.com>
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Tatsh commented Jan 17, 2026

Please consider adding https://github.com/Tatsh/tatsh-overlay/blob/master/dev-qt/qtwebkit/files/qtwebkit-fix-qttestbrowser-build.patch to this PR.

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whitslack commented Jan 17, 2026 •
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@Tatsh: Thank you for testing. I wasn't building with tests enabled, so I didn't catch the missing piece. Do you know for certain that NetworkPrivateCorePrivate is required here? Your error message only mentioned a private header from GuiPrivate.

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Tatsh commented Jan 18, 2026

I assume you mean CorePrivate. Once I ran with the GuiPrivate includes another error occurred regarding CorePrivate.

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whitslack commented Jan 18, 2026

@Tatsh: Yes, I did. And does it not work if you append to QtTestBrowser_PRIVATE_LIBRARIES (rather than QtTestBrowser_LIBRARIES)? (The former will not be propagated to dependent targets.)

@whitslack whitslack force-pushed the fix-private-headers branch from 5420bec to 949c35a Compare January 18, 2026 00:20
@whitslack
cmake: fix finding Qt private headers with Qt >=6.10
02ec306 
Qt private header directories only get added to the include search path
when the "Qt6::${component}Private" library is added to the target.
@whitslack whitslack force-pushed the fix-private-headers branch from 949c35a to 02ec306 Compare May 11, 2026 19:50
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whitslack commented May 11, 2026
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The merged fixes are a good start, but they miss some key points. See comments.

Comment thread Source/cmake/OptionsQt.cmake
Comment on lines 73 to 99
macro(CHECK_Qt6_PRIVATE_INCLUDE_DIRS _qt_component _header)
# Qt6 provides private headers via Qt6::${_qt_component}Private target
find_package(Qt6${_qt_component}Private QUIET CONFIG)
set(CMAKE_REQUIRED_LIBRARIES Qt6::${_qt_component})

if (NOT TARGET Qt6::${_qt_component}Private)
message(FATAL_ERROR "Qt6::${_qt_component}Private target not found. Please make sure Qt6 private headers are installed.")
endif()
# Qt 6.10+ provides private headers via Qt6::${_qt_component}Private target
if (Qt6${_qt_component}_VERSION VERSION_GREATER_EQUAL 6.10)
find_package(Qt6 ${REQUIRED_QT_VERSION} REQUIRED COMPONENTS ${_qt_component}Private)
list(APPEND CMAKE_REQUIRED_LIBRARIES Qt6::${_qt_component}Private)
endif ()

set(INCLUDE_TEST_SOURCE
"
#include <${_header}>
int main() { return 0; }
"
)

# Use the Private target directly - it provides the include dirs automatically
set(CMAKE_REQUIRED_LIBRARIES Qt6::${_qt_component} Qt6::${_qt_component}Private)

check_cxx_source_compiles("${INCLUDE_TEST_SOURCE}" Qt6${_qt_component}_PRIVATE_HEADER_FOUND)

unset(INCLUDE_TEST_SOURCE)
unset(CMAKE_REQUIRED_LIBRARIES)

if (NOT Qt6${_qt_component}_PRIVATE_HEADER_FOUND)
message(FATAL_ERROR "Header ${_header} is not found. Please make sure that:
1. Private headers of Qt6${_qt_component} are installed
2. Qt6${_qt_component}Private package is available")
endif ()
endmacro()
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@whitslack whitslack May 11, 2026

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The *Private targets were only added starting in Qt 6.10, so you need a VERSION_GREATER_EQUAL conditional.

Also, if you specify REQUIRED in the find_package call, then you don't need to write an explicit FATAL_ERROR message.

Comment thread Tools/QtTestBrowser/CMakeLists.txt
Comment on lines 45 to +63
@@ -55,6 +54,13 @@ if (TARGET Qt6::PrintSupport)
list(APPEND QtTestBrowser_LIBRARIES Qt6::PrintSupport)
endif ()

if (Qt6Core_VERSION VERSION_GREATER_EQUAL 6.10)
list(APPEND QtTestBrowser_PRIVATE_LIBRARIES Qt6::CorePrivate)
endif ()
if (Qt6Gui_VERSION VERSION_GREATER_EQUAL 6.10)
list(APPEND QtTestBrowser_PRIVATE_LIBRARIES Qt6::GuiPrivate)
endif ()

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Qt6::GuiPrivate does not belong in QtTestBrowser_LIBRARIES, as it would "infect" dependents with the private dependency. Put it in QtTestBrowser_PRIVATE_LIBRARIES so it will not be transitory.

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@whitslack @Tatsh