qt: fix Platform component

[maksim-petukhov]

Summary

Changes to recipe: qt/6.x

Motivation and Details

Qt6::Platform component and its relationship with Qt6::Core differ from the upstream ones. This prevents me from compiling one of the closed-source libraries (QtitanRibbon) using Qt6 taken from CCI.

Actually Qt6::Core depends on Qt6::Platform, see <package>\lib\cmake\Qt6Core\Qt6CoreTargets.cmake:

set_target_properties(Qt6::Core PROPERTIES
  COMPATIBLE_INTERFACE_STRING "QT_MAJOR_VERSION;QT_COORD_TYPE"
  INTERFACE_COMPILE_DEFINITIONS "QT_CORE_LIB"
  INTERFACE_INCLUDE_DIRECTORIES "${_IMPORT_PREFIX}/include/QtCore;${_IMPORT_PREFIX}/include"
  INTERFACE_LINK_LIBRARIES "Qt6::Platform;mpr;userenv;WrapAtomic::WrapAtomic;\$<\$<AND:\$<NOT:\$<BOOL:\$<TARGET_PROPERTY:qt_no_entrypoint>>>,\$<STREQUAL:\$<TARGET_PROPERTY:TYPE>,EXECUTABLE>,\$<BOOL:\$<TARGET_PROPERTY:WIN32_EXECUTABLE>>>:Qt6::EntryPointPrivate>"
  ...
)

And -permissive- and -Zc:__cplusplus flags come from Qt6::Platform, not from Qt6::Core, see <package>\lib\cmake\Qt6\Qt6Targets.cmake:

# Create imported target Qt6::Platform
add_library(Qt6::Platform INTERFACE IMPORTED)

set_target_properties(Qt6::Platform PROPERTIES
  INTERFACE_COMPILE_DEFINITIONS "WIN32;_ENABLE_EXTENDED_ALIGNED_STORAGE;WIN64;_WIN64;\$<\$<NOT:\$<BOOL:\$<TARGET_PROPERTY:QT_NO_UNICODE_DEFINES>>>:UNICODE\$<SEMICOLON>_UNICODE>"
  INTERFACE_COMPILE_FEATURES "cxx_std_17"
  INTERFACE_COMPILE_OPTIONS "\$<\$<AND:\$<CXX_COMPILER_ID:MSVC>,\$<COMPILE_LANGUAGE:CXX>>:-Zc:__cplusplus;-permissive->;\$<\$<AND:\$<NOT:\$<BOOL:\$<TARGET_PROPERTY:QT_NO_UTF8_SOURCE>>>,\$<COMPILE_LANGUAGE:C,CXX>>:\$<\$<CXX_COMPILER_ID:MSVC>:-utf-8>>"
  INTERFACE_INCLUDE_DIRECTORIES "${_IMPORT_PREFIX}/mkspecs/win32-msvc;${_IMPORT_PREFIX}/include"
  INTERFACE_LINK_LIBRARIES "Threads::Threads"
  _qt_package_version "6.7.3"
)

there we can also see that it "links" to Threads::Threads. There are also conditional compile definitions and compile options which are missing (_UNICODE and -utf-8). You can look at this file https://github.com/qt/qtbase/blob/92b685784960eea6eb353688cf0edeb94d69c6cd/cmake/QtPlatformTargetHelpers.cmake#L61 to get a better idea where they come from (see calls to qt_set_msvc_cplusplus_options, qt_enable_utf8_sources, qt_internal_enable_unicode_defines). And you can also notice that Qt6::Platform requires log library on Android.

These changes are also required for these documented functions to work: https://doc.qt.io/qt-6/qt-disable-unicode-defines.html, https://doc.qt.io/qt-6/qt-allow-non-utf8-sources.html.

---

• Read the contributing guidelines
• Checked that this PR is not a duplicate: list of PRs by recipe
• Tested locally with at least one configuration using a recent version of Conan

[maksim-petukhov]

@jcar87 @uilianries @perseoGI @AbrilRBS @franramirez688 friendly pinging for a review

[uilianries]

@maksim-petukhov Hello 👋

Thank you for giving those details, it's clear there is a window for improvement.

This prevents me from compiling one of the closed-source libraries (QtitanRibbon) using Qt6 taken from CCI.

At least you could inform what error occurs and the compilation error? So we can have a better view of the current limitation of this component.

[maksim-petukhov]

@uilianries Hi

I believe these were the compilation errors:

D:/conan2/qtd87b8da2e6f46/p/lib/cmake/Qt6Core/../../../include/QtCore/6.7.3\QtCore/private/qthread_p.h(20,10): fatal error C1083: Cannot open include file: qplatformdefs.h: No such file or directory, (compiling D:\conan2\b\qtitaa7da151c5cba7\b\src\base\QtnBackstageWidget.cpp) [D:\conan2\b\qtitaa7da151c5cba7\b\build\QtitanRibbon.vcxproj]

D:\conan2\b\qtitaa7da151c5cba7\b\src\base\QtnPlatform_win.cpp(1328,64): error C2664: "QFont QWindowsFontDatabaseBase::LOGFONT_to_QFont(const LOGFONT &,int)": cannot convert argument 1 from "const LOGFONTW" to "const LOGFONT &" [D:\conan2\b\qtitaa7da151c5cba7\b\build\QtitanRibbon.vcxproj]

The initial comment in this PR already includes some context around the issue: this component is clearly not aligned with the upstream version. Feel free to take another look at the initial comment when you get a chance - that might help clarify things a bit further

[maksim-petukhov]

@uilianries is there anything else I can do to move this forward?

[uilianries]

@maksim-petukhov Hello, we have been discussing internally about this PR and we doing a very detailed review, as the Qt package is really fragile and affects several users.

My only concern right now is the UTF-8 extra code in this PR. It fits for this current version, but it's one more extra point to be always reviewed in the future, to make sure nothing changed in Qt and result in unexpected behavior based on the upstream.