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/****************************************************************************
**
** Copyright (C) 2022 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Creator documentation.
**
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Free Documentation License Usage
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of
** this file. Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
**
****************************************************************************/
// **********************************************************************
// NOTE: the sections are not ordered by their logical order to avoid
// reshuffling the file each time the index order changes (i.e., often).
// Run the fixnavi.pl script to adjust the links to the index order.
// **********************************************************************
/*!
\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
The clangd \e index provides exact and complete results for services such
as finding references, following symbols under cursor, and using the
locator, even for complex constructs. 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.
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 specify settings for clangd:
\list 1
\li Select \uicontrol Tools > \uicontrol Options > \uicontrol C++ >
\uicontrol Clangd > \uicontrol {Use clangd}.
\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
*/
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