// Copyright (C) 2020 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
\page porting-to-qt6-using-clazy.html
\title Porting C++ Applications to Qt 6 using Clazy checks

    We've implemented some checks and fixits within the Clazy framework to
    help you port your applications from Qt 5 to Qt 6.
    In their own words: "Clazy is a compiler plugin which allows clang to
    understand Qt semantics". Get Clazy (\l{https://invent.kde.org/sdk/clazy})
    and read on to make porting to Qt 6 smoother.

    Clazy checks can be run as a plugin during compilation or over a JSON
    compilation database using \c clazy-standalone.
    The fixes are applied later, using \c clang-apply-replacements.

    \section1 Clazy checks dedicated to Qt 6 porting

    The following checks are dedicated to ease the port from Qt 5 to Qt 6.
    \list
        \li \c qt6-deprecated-api-fixes
        \li \c qt6-header-fixes
        \li \c qt6-qhash-signature
        \li \c qt6-fwd-fixes
        \li \c missing-qobject-macro
    \endlist

    The checks have to be run against Qt 5. The fixed code is only going to
    compile against Qt 6. For this reason the above mentioned checks have to be
    run in one go. Clazy recommends running one test at a time to avoid
    conflict when applying fixes, but this is not an option when running those
    checks as a plugin.

    \section1 How to apply Clazy checks

    How to set up your project to run with Clazy and how to select and apply
    the checks is fully explained here:
    \l {https://invent.kde.org/sdk/clazy#setting-up-your-project-to-build-with-clazy}.

    If you don't want to run the checks as a plugin but rather over a JSON
    compilation database, you need to use \c clazy-standalone. Please see
    \l {https://invent.kde.org/sdk/clazy#clazy-standalone-and-json-database-support}
    for instructions.

    In a nutshell, assuming you have an up to date Clazy version installed, what needs
    to be done to run the checks as a plugin is explained below.

    Set up your project to run with Clazy.
    \section2 If using qmake
    Add the following lines to your qmake command, as appropriate for your OS:
    \code
    -spec linux-clang QMAKE_CXX="clazy"
    -spec macx-clang QMAKE_CXX="clazy"
    \endcode
    For Windows with MSVC add \c QMAKE_CXX="clazy-cl.bat".

    Run qmake.

    \section2 If using CMake
    Add: \c -DCMAKE_CXX_COMPILER=clazy to the cmake command.

    Run cmake.

    Select the checks:
    \code
    export CLAZY_CHECKS="qt6-deprecated-api-fixes,qt6-header-fixes,
    qt6-qhash-signature,qt6-qlatin1stringchar-to-u,qt6-fwd-fixes,missing-qobject-macro"
    \endcode

    Enable the fixits:
    \code
    export CLAZY_EXPORT_FIXES=ON
    \endcode

    Set the directories to be ignored by Clazy:
    \code
    export CLAZY_IGNORE_DIRS=.*lib_dir.*
    \endcode
    This will prevent Clazy checks from running on the libraries' files.
    This is necessary if the libraries' paths are included
    with \c -I and \c -F instead of \c -isystem and \c -framework.
    This is also necessary to avoid warnings from \c qt-header-fixes check,
    if the headers triggering the check are included in the included
    libraries' files.

    Compile your code.

    During compilation \c {.yaml} files are created next to the source files.

    To apply the fixits, run:
    \code
    clang-apply-replacements <path_to_yaml_files>
    \endcode
    This will modify the source files, consider backing up your code.

    If there are some conflicts between the fixits, you will be notified and no
    file will be changed.

    Not all porting can be done with automatic fixits. Please look carefully at
    the warnings during compilation for the code that will have to be changed
    manually.

    \section1 How to apply Clazy checks within \QC

    You can access Clazy checks within \QC by selecting \uicontrol Tools >
    \uicontrol Options > \uicontrol Analyzer (or \uicontrol {\QC} >
    \uicontrol Preferences > \uicontrol Analyzer on macOS).

    You must create your own configuration and select the Clazy checks dedicated
    to porting that you can find under Level 2 and Manual Level sections in
    \QC version 4.14.1, or later. You can use the \e qt6 filter to locate
    most of the checks. Be careful to select only the checks present in the above
    given list.

    \image qtcreator-clazy-checks-for-porting-to-qt6.png "Filtering Qt 6 checks"

    \note We recommend that you deselect all other checks, except the porting
    checks, to make it easier to apply fixits and to avoid unnecessary
    conflicts.

    To run the checks, select \uicontrol Analyze > \uicontrol {Clang-Tidy and Clazy}.

    For more information about configuring and running Clazy checks, see
    \l{\QC: Clang Tools}.

    \section2 A word of caution

    Within \QC, conflicts between fixits are not being warned against.
    If there is more than one fixit on the same line, be careful when applying
    the fixits.

    Once a fixit has been applied, running the checks again will fail, because
    the new code will only compile against Qt 6.

*/

