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/*!
    \previouspage creator-diff-editor.html
    \page creator-clang-codemodel.html
    \nextpage creator-finding-overview.html

    \title Parsing C++ Files with the Clang Code Model

    The \e {code model} is the part of an IDE that understands the language you
    are using to write your application. It is the framework that allows \QC
    to provide the following services:

    \list

        \li \l{Completing Code}{Code completion}

        \li Syntactic and \l{Semantic Highlighting}{semantic highlighting}

        \li Navigating in the code by using the \l{Searching with the Locator}
            {locator}, \l{Moving to Symbol Definition or Declaration}
            {following symbols}, and so on

        \li Inspecting code by using the \l{Browsing Project Contents}
            {class browser}, the \l{Viewing Defined Types and Symbols}
            {outline}, and so on

        \li Diagnostics

        \li \l{Viewing Function Tooltips}{Tooltips}

        \li \l{Finding Symbols}{Finding and renaming symbols}

        \li \l{Applying Refactoring Actions}{Refactoring actions}

    \endlist

    \QC comes with a plugin that provides some of these services
    for C++ on top of \l{http://clang.llvm.org/}{Clang}.

    \section1 About the Clang Code Model

    The Clang project provides libraries for parsing
    C language family source files. The feedback you get through warning and
    error markers is the same as a compiler will give you, not an incomplete
    set or a close approximation, as when using the built-in \QC code model.
    Clang focuses on detailed information for diagnostics, which is really
    useful if the code contains typos, for example.

    Clang keeps up with the development of the C++ language. At the time of this
    writing, it supports C++98/03, C++11, C++14, C++17, C89, C99, Objective-C,
    and Objective-C++.

    On the downside, for large projects using Clang as code model is slower than
    using the built-in code model. Clang does not need to generate object files,
    but it still needs to parse and analyze the source files. For small projects
    that only use STL, this is relatively fast. But for larger projects that
    include several files, processing a single file and all the included files
    can take a while.

    The Clang code model plugin now provides some of the services that were
    previously provided by the built-in C/C++ code model. Currently, the
    following services are implemented:

    \list

        \li Code completion
        \li Syntactic and semantic highlighting
        \li \l{Using Clang Tools}{Diagnostics}
        \li Outline of symbols
        \li Tooltips
        \li Renaming of local symbols

    \endlist

    To use the built-in code model instead, select \uicontrol Help >
    \uicontrol {About Plugins} > \uicontrol C++, and deselect the
    \uicontrol ClangCodeModel check box. Select \uicontrol {Restart Now}
    to restart \QC and have the changes take effect.

    You can configure Clang diagnostics either globally or separately for:

    \list
        \li Clang code model (globally or at project level)
        \li \l{Using Clang Tools}{Clang tools} (globally or at project level)
    \endlist

    \section1 Configuring Clang Code Model

    To configure the Clang code model globally:

    \list 1

        \li Select \uicontrol Tools > \uicontrol Options > \uicontrol C++ >
            \uicontrol {Code Model}.

            \image qtcreator-clang-code-model-options.png

        \li To instruct the code model to interpret ambiguous header files as C
            language files if you develop mainly using C, select the
            \uicontrol {Interpret ambiguous headers as C headers} check box.

        \li To process precompiled headers, deselect the
            \uicontrol {Ignore precompiled headers} check box.

        \li To avoid out-of-memory crashes caused by indexing huge source files
            that are typically auto-generated by scripts or code, the size of
            files to index is limited to 5MB by default. To adjust the limit,
            edit the value for the \uicontrol {Do not index files greater than}
            check box. To index all files, deselect the check box.

        \li The \uicontrol {Diagnostic Configuration} field shows the Clang
            checks to perform. Click the value of the field to open the
            \uicontrol {Diagnostic Configurations} dialog, where you can
            select and edit the checks to perform.

            \image qtcreator-diagnostics-configuration.png

    \endlist

    \section1 Configuring clangd

    You can use the experimental clangd support instead of libclang to receive
    exact and complete results for services such as finding references,
    following symbols under cursor, and using the locator, even for complex
    constructs that the built-in code model cannot handle correctly. These
    improvements are based on clangd's \e index. When you \l{Opening Projects}
    {open a project}, clangd scans the source files to generate the index. For
    large projects, this can take a while, but the index is persistent and
    re-scanning is incremental, so nothing is lost by closing and re-starting
    \QC.

    Because clangd considers only the on-disk state of included header files
    when parsing a source file, you need to save changes in header files to
    have them considered elsewhere for completion, diagnostics, and so on.
    Partly for this reason, files that are changed by refactoring actions are
    saved automatically. To disable this feature, select \uicontrol Tools >
    \uicontrol Options > \uicontrol Environment > \uicontrol System >
    \uicontrol {Auto-save files after refactoring}.

    The document outline in the \l{Viewing Defined Types and Symbols}
    {Outline} view is backed by clangd's document symbol support, which
    makes the results more reliable than before.

    To use clangd for the current project instead of the built-in code model or
    Clang:

    \list 1
        \li Select \uicontrol Tools > \uicontrol Options > \uicontrol C++ >
            \uicontrol Clang > \uicontrol {Use clangd (EXPERIMENTAL)}.
            \image qtcreator-options-clangd.png "clangd options"
        \li In \uicontrol {Path to executable}, enter the path to clangd
            version 13, or later.
        \li For more accurate results during global symbol searches, select
            \uicontrol {Enable background indexing}. However, this increases the
            CPU load the first time you open the project.
        \li Select \uicontrol {Insert header files on completion} to allow
            clangd to insert header files as part of symbol completion.
        \li By default, clangd attempts to use all unused cores. You can set a
            fixed number of cores to use in \uicontrol {Worker thread count}.
        \li In \uicontrol {Document update threshold}, specify the amount of
            time \QC waits before sending document changes to the server.
            If the document changes again while waiting, this timeout is reset.
    \endlist

    \section1 Clang Checks

    In addition to using the built-in checks, you can select \uicontrol Copy to
    create copies of them and edit the copies to fit your needs.

    \uicontrol {Build-system warnings} displays warnings as specified
    by the build system.

    \uicontrol {Checks for questionable constructs} combines the \c -Wall and
    \c -Wextra checks for easily avoidable questionable constructions and some
    additional issues.

    Clang checks begin with \c -W. Each check also has a negative version that
    begins with \c -Wno.

    Keep in mind that some options turn on other options. For more information,
    see \l{https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html}
    {Options to Request or Suppress Warnings} or the GCC or Clang manual pages.

    \section1 Specifying Clang Code Model Settings at Project Level

    You can specify Clang code model settings at project level by selecting
    \uicontrol Projects > \uicontrol {Clang Code Model}.

    In addition to configuring the diagnostics,
    you can select the \uicontrol {Enable MSVC-compliant template parsing} check
    box to parse templates in a MSVC-compliant way. This enables Clang to parse
    headers for example from Active Template Library (ATL) or Windows Runtime
    Library (WRL). However, using the relaxed and extended rules means that no
    highlighting or completion can be provided within template functions.

    \image qtcreator-clang-code-model-build-settings.png

    \include creator-compilation-database.qdocinc using compilation databases

*/
