yacreader/Qt5-DROP.md

Qt5 Drop - Cleanup Checklist

Inventory of all Qt5 compatibility code and version branching across the project. Goal: support only Qt6, remove all Qt5 conditionals and dead branches.

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1. Build System (.pro / .pri files)

core5compat module additions

These add QT += core5compat for Qt6 builds. Needed by third-party QtWebApp (QTextCodec, QRegExp).

File	Line	Code
YACReaderLibrary/YACReaderLibrary.pro	51	greaterThan(QT_MAJOR_VERSION, 5): QT += core5compat
YACReader/YACReader.pro	53	greaterThan(QT_MAJOR_VERSION, 5): QT += core5compat
YACReaderLibraryServer/YACReaderLibraryServer.pro	20	greaterThan(QT_MAJOR_VERSION, 5): QT += core5compat
YACReaderLibraryServer/YACReaderLibraryServer.pro	40	greaterThan(QT_MAJOR_VERSION, 5): QT += core5compat (duplicate)

Action: Replace conditionals with unconditional QT += core5compat (still needed for QtWebApp). Remove the duplicate in YACReaderLibraryServer.

macextras module (Qt5-only, removed in Qt6)

File	Line	Code
YACReaderLibrary/YACReaderLibrary.pro	44	lessThan(QT_MAJOR_VERSION, 6): QT += macextras
YACReader/YACReader.pro	48	lessThan(QT_MAJOR_VERSION, 6): QT += macextras

Action: Remove these lines entirely.

gui-private module (Qt 6.7+)

File	Line	Code
YACReaderLibrary/YACReaderLibrary.pro	53-55	greaterThan(QT_MAJOR_VERSION, 5):greaterThan(QT_MINOR_VERSION, 6) { QT += gui-private }
YACReader/YACReader.pro	55-57	Same

Action: Simplify to greaterThan(QT_MINOR_VERSION, 6): QT += gui-private (drop the Qt5 guard).

Poppler backend version branching

File	Lines	What
dependencies/pdf_backend.pri	60-84	Qt5 uses poppler-qt5, Qt6 uses poppler-qt6 (pkg-config, include paths, link flags)

Action: Keep only the Qt6 (poppler-qt6) branch, remove poppler-qt5 paths.

Minimum version check

File	Lines	What
config.pri	18-41	minQtVersion() function, enforces minimum Qt 5.15.0

Action: Update minimum to Qt 6.x.

QML resource branching (DONE)

File	Lines	What
YACReaderLibrary/YACReaderLibrary.pro	317-321	Was greaterThan(QT_MAJOR_VERSION, 5) { qml6.qrc } else { qml.qrc }

Action: Already cleaned up - now unconditional RESOURCES += qml.qrc.

Qt4 compatibility in third-party

File	Line	Code
third_party/QsLog/QsLog.pri	11	greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

Action: Replace with unconditional QT += widgets.

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2. C++ Source Code (#if QT_VERSION checks)

Qt5 vs Qt6 API changes (own code)

File	Line(s)	Qt5 branch	Qt6 branch	API change
common/pdf_comic.h	49	#include "poppler-qt5.h"	#include <poppler-qt6.h>	Poppler header
common/pdf_comic.mm	3	(nothing)	#undef __OBJC_BOOL_IS_BOOL	macOS ObjC compat
common/comic.cpp	812	auto _pdfComic = Poppler::Document::load()	pdfComic = Poppler::Document::load()	Poppler return type
YACReaderLibrary/initial_comic_info_extractor.cpp	44	Same Poppler pattern	Same	Poppler return type
YACReader/mouse_handler.cpp	22, 56, 107	QPointF(event->x(), event->y())	event->position()	QMouseEvent API
YACReader/viewer.cpp	762	pixmap(Qt::ReturnByValue)	pixmap()	QPixmap return semantics
custom_widgets/help_about_dialog.cpp	14, 88	QTextCodec / setCodec()	QStringConverter / setEncoding()	Text encoding API
YACReader/translator.cpp	291	player->setMedia()	player->setSource()	QMediaPlayer API
YACReaderLibrary/comic_vine/comic_vine_dialog.cpp	149, 160	QtConcurrent::run(this, &fn, args)	QtConcurrent::run(&fn, this, args)	Argument order
YACReaderLibrary/library_window.cpp	173	Different key handling	keySequence[0] (QKeyCombination)	Key event API
YACReaderLibrary/library_window.cpp	790-793	Qt5 toolbar connections	Qt6 toolbar connections	macOS toolbar
YACReader/main_window_viewer.cpp	483, 1357	Qt5 toolbar/slider	Qt6 toolbar/slider	macOS toolbar
YACReaderLibrary/trayhandler.mm	3	(nothing)	#undef __OBJC_BOOL_IS_BOOL	macOS ObjC compat
YACReader/main.cpp	102	(nothing)	QImageReader::setAllocationLimit(0)	Image reader limit
YACReaderLibraryServer/main.cpp	53	(nothing)	QImageReader::setAllocationLimit(0)	Image reader limit

Action: For each, keep only the Qt6 branch, remove the #if/#else/#endif and the Qt5 code.

Qt4 vs Qt5 leftovers (very old)

File	Line(s)	What
custom_widgets/yacreader_table_view.cpp	31, 39, 46	#if QT_VERSION >= 0x050000 — setResizeMode vs setSectionResizeMode
YACReaderLibrary/comic_vine/scraper_tableview.cpp	9, 16, 23	Same Qt4 vs Qt5 header API
YACReader/translator.cpp	3, 164	#if QT_VERSION >= 0x050000 — Phonon vs QMediaPlayer
YACReader/main.cpp	135	#if QT_VERSION >= 0x050800 — QCommandLineOption::HiddenFromHelp

Action: Remove the #if guards entirely, keep only the Qt5+ code (which is also valid Qt6).

Qt 6.7+ specific (RHI widget)

File	Lines	What
common/rhi/yacreader_flow_rhi.h	8-302	#if QT_VERSION >= QT_VERSION_CHECK(6, 7, 0) — entire QRhiWidget implementation

Action: Keep this conditional (gates on Qt 6.7 minor version, not Qt5 vs Qt6).

Qt 6.9+ specific (test code)

File	Line	What
tests/concurrent_queue_test/concurrent_queue_test.cpp	212	#if QT_VERSION < QT_VERSION_CHECK(6, 9, 0) — QDebug for std::array

Action: Keep this conditional (Qt6 minor version gate).

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3. Third-Party Libraries

QtWebApp (third_party/QtWebApp/)

File	Lines	What
templateengine/templateengine.pri	5	QT += core5compat
templateengine/templateloader.cpp	13, 77, 86, 107	QRegExp→QRegularExpression, QString::split flag
httpserver/httpconnectionhandler.h	23	tSocketDescriptor typedef (Qt4 vs Qt5)
httpserver/httpconnectionhandlerpool.cpp	152	SSL cert handling (Qt <5.15 vs 5.15+)

Action: Decide whether to update QtWebApp or replace it. If updating: remove Qt4/Qt5 branches, keep Qt6 code, potentially drop core5compat dependency by migrating QTextCodec→QStringConverter and QRegExp→QRegularExpression.

QsLog (third_party/QsLog/)

File	Lines	What
QsLog.pri	11	Qt4 widgets guard
QsLogDestFile.cpp	32, 157, 179	QTextCodec vs QStringConverter
QsLogWindow.cpp	129	Qt4 header resize API

Action: Same approach — remove Qt4/Qt5 branches, keep Qt6 code.

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4. CI/CD and Build Scripts

GitHub Actions (.github/workflows/build.yml)

Qt5 build targets to remove:

• Ubuntu Linux Qt5 build (~line 63)
• Windows x64 Qt5 build (~line 346)
• Windows x86 Qt5 build (~line 798)
• macOS Qt5 build (~line 201)

Qt6 build targets to keep (and simplify):

• Linux Qt6 builds (~lines 90, 116)
• macOS Qt6 Universal (~line 145) — still installs qt5compat module (needed for QtWebApp)
• Windows x64 Qt6 (~line 408) — same
• Windows ARM64 Qt6 (~line 574) — same

Build scripts

File	What
build_scripts/ubuntu_24.04/build.sh	Qt6 — installs libqt6core5compat6-dev, qml6-module-qt5compat-graphicaleffects
build_scripts/ubuntu_22.04/build.sh	Qt5 — entire script is Qt5-only

Action: Remove ubuntu_22.04 build script. In ubuntu_24.04, remove qml6-module-qt5compat-graphicaleffects (no longer used in QML). Keep libqt6core5compat6-dev (needed for QtWebApp).

Docker

File	What
docker/Dockerfile	Ubuntu x64 Qt6 — installs libqt6core5compat6-dev (build) and libqt6core5compat6 (runtime)
docker/Dockerfile.aarch64	Ubuntu ARM64 Qt5-only build

Action: Convert Dockerfile.aarch64 to Qt6. Keep core5compat packages in main Dockerfile (QtWebApp). Make sure the conversion is good, there must be other images online that use the arm+qt6 combo, we can search online.

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5. Summary

Safe to remove now (no dependencies)

• All lessThan(QT_MAJOR_VERSION, 6) lines (macextras)
• All #if QT_VERSION >= 0x050000 / 0x050800 guards (Qt4 leftovers)
• All Qt5 CI build targets
• build_scripts/ubuntu_22.04/ (Qt5-only)
• qml6-module-qt5compat-graphicaleffects from build scripts (QML migration done)

Requires code changes (keep Qt6 branch only)

• ~15 #if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0) blocks in own code
• Poppler backend selection in pdf_backend.pri
• config.pri minimum version bump

Keep as-is (Qt6 minor version gates)

• QT_VERSION_CHECK(6, 7, 0) — RHI widget
• QT_VERSION_CHECK(6, 9, 0) — test code
• gui-private for Qt 6.7+ (simplify guard only)

Depends on third-party decisions

• core5compat — still needed unless QtWebApp and QsLog are updated to drop QTextCodec/QRegExp