How to Resolve QDoc Warnings | Qt 6.10

- Qt 6.10
- QDoc Manual
- How to Resolve QDoc Warnings
- Qt 6.10.3 Reference Documentation

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# How to Resolve QDoc Warnings

QDoc may issue warnings when generating your documentation set. This section describes what these warnings mean and how to resolve them. This document does not describe warnings generated by Clang.

## Can't link to <target>

QDoc issues this warning when one part of the documentation (identified in the warning message) tries to refer to another, but doesn't correctly specify that other, the target of the link. This may arise because the reference to it is mistyped or because the target has changed name (for a function or type) or title (for another section).

Search the source code for that particular link target. If you get no results, gradually make the search less specific until you find a match.

If the link target looks like the name of a type or function, this could also be due to:

- The name (or, for functions, where specified, signature) used where it is documented not matching the name used in its declaration.
- The link target being marked as \internal when the linking text was not.

## Found a \target command outside table item in a table

If QDoc encounters a \target command that is not preceded by an \li command within a \table ... \endtable block, it issues this warning. The warning is followed by the text Move the \target inside the \li to resolve this warning.

## Cannot find snippets file to quote from

QDoc issues this warning if it is unable to find the file named after a \snippet or \quotefromfile command.

Some useful steps for correcting this:

- Check if the snippet file name is correct. QDoc appends the snippet file name to each of the directories given in the search path, to get a path-name for a candidate file to look for. It produces this error when none of these candidates exist.
- Check the search path for snippets, given by the `exampledirs` configuration variable in the `*.qdocconf` file. You may need to add an entry to this path, or correct an existing entry.
- Check if the snippet file exists, or if it has been moved, renamed or removed, which may happen when there are changes to the source code that QDoc tries to quote from.

## Unexpected \snippet

QDoc issues this warning if it is unable to locate the snippet file quoted in a \snippet command.

## Undocumented QML <module> referred by <type> or its members

QDoc issues this warning if it is unable to locate a QML module based on the identifier passed to the \inqmlmodule or \qmlproperty commands associated with a QML type.

This means that either documentation for the \qmlmodule is missing, or an incorrect module identifier was used in \qmlproperty, \qmlmethod, or \qmlsignal command(s).

## No such <type> in QML <module>

QDoc issues this warning if a \qmlproperty, \qmlmethod, or \qmlsignal command argument uses a QML module identifier, but the associated \qmltype does not belong to that module.

The QML module identifier, if defined, must match with the \inqmlmodule argument in the QML type documentation. In most cases, QDoc is able to locate the QML type without a module identifier.

## Undocumented return value

For functions whose return-type is not void, QDoc checks if the return value is documented. This warning is issued if the documentation for a function or method doesn't contain a word starting with "return".

## Undocumented parameter

QDoc requires the documentation of a function or method to describe every parameter. It recognizes this by each parameter name (as specified where the function or method is declared in a header file) appearing after a \a command.

This requirement is not imposed for function overload documentation, provided that the overload is marked with the `\overload` command and a fully-documented function with the same name exists.

## No such parameter

QDoc issues this warning when the parameter name given after an \a command does not match any of the parameters named in the header-file's declaration of the function or method being documented.

## Unknown macro

QDoc issues this warning when it sees a backslash, `\`, followed by a token it doesn't recognize as the name of either a built-in command or a user-defined macro. When quoting code that contains character escape sequences, you should enclose the code in \c{...} to prevent this warning against the escape sequences.

## Failed to find function when parsing \fn <signature>

When Clang parses a function signature following an `\fn` command, it checks this against the declaration in the header file. If Clang discovers discrepancies, it issues this warning message.

The signature must be fully qualified. Typical issues include missing or incorrect template arguments, return type, or qualifiers such as const.

Note: The `\fn` signature for a hidden friend should be fully qualified with the scope of the class that declares the function.

## QML type <TypeName> documented with <ClassName> as its native type. Replacing <ClassName> with <OtherClass>

If the `\nativetype` command is used with the same argument in multiple QML type documentation comments that belong to the same documentation project, QDoc issues this warning. To resolve this, ensure that you use the `\nativetype` command only once for each C++ class.

## Cannot tie this documentation to anything

QDoc found a /*! ... */ comment, with no topic command, that was not immediately followed by a class, function or property definition. It thus does not know what the comment documents.

## This qdoc comment contains no topic command (e.g., \module, \page)

If a QDoc comment doesn't contain a topic command, QDoc does not know what the comment documents, and issues this warning. Very similar to Cannot tie this documentation to anything, but specific to comments that are not in C++ or QML files.

## <name> documented more than once

QDoc issues this warning when it finds two comments that document the same item. The location of the previously seen comment is provided in warning details.

For example, you see this warning when a function has a documentation comment preceding its definition, and a separate \fn comment elsewhere.

## <topic> cannot be mixed with other topic commands

QDoc allows multiple topic commands in a single documentation comment for certain use cases. Using multiple topic commands from different categories prints out this warning, and the topic generates no output.

## Namespace <name> documented more than once

This warning means that a documentation set contains two comments containing \namespace commands with the same argument, <name>.

## <name> is documented, but namespace <namespace> is not documented in any module

The documentation for <name> was found, but <name> is declared under a namespace that is either undocumented or QDoc was unable to locate the documentation for it.

This can be resolved by either documenting <namespace>, or if it is already documented in another module, ensure that this module has a dependency to it.

See also depends and indexes.

## Has no \inmodule command

QDoc issues this warning if the QDoc comments do not relate a class, namespace, or headerfile to a module with the \inmodule command.

If the QDoc comment describes an entity that's not a member of some other entity (typically a namespace or class), it should use either \relates or \inmodule to associate it with its broader context. This warning is raised if it does not.

## Cannot find <name> specified with \<command> in any header file

This means that QDoc cannot find a declaration of <name> in any header file, but has found a comment that claims to document it.

An example:

     Cannot find 'Color::Red' specified with '\enum' in any header file.

A documentation comment claims to describe an enum, but QDoc didn't find a definition of that enum in a header file.

This may also be due to:

- a typo in <name> or <command>
- a missing namespace-or-class prefix
- <name> having moved to another namespace or class

## Unrecognizable QML module/type qualifier for <identifier>

A parameter passed to \qmlproperty or \qmlmethod contains a combination of qmlModule::qmlType::identifier that is not defined anywhere.

Example:

     Unrecognizable QML module/type qualifier for real QtQuick::DragHandler::DragAxis::minimum

DragHandler doesn't have a property called DragAxis.

## Missing property type for <name>

A declaration of a \qmlproperty is missing its property type.

The \qmlproperty command expects to be followed by the property type, then the fully-qualified name of the property (i.e. the name ::-joined after the name of the class it belongs to).

Incorrect:

     \qmlproperty MyWidget::count

Correct:

     \qmlproperty int MyWidget::count

## QML property documented multiple times: <identifier>

QDoc uses this warning when it finds two QDoc comments that document the same QML property, either by appearing just before its definition, or using the \qmlproperty command.

## Command <command> not allowed with QML property commands

Example:

     \qmlproperty real QtQuick.Controls::RangeSlider::first.value
     \qmlproperty real QtQuick.Controls::RangeSlider::first.position
     \qmlproperty real QtQuick.Controls::RangeSlider::first.visualPosition
     \qmlsignal void QtQuick.Controls::RangeSlider::first.moved()
     \qmlsignal void QtQuick.Controls::RangeSlider::second.moved()

Error message:

     Command '\\qmlsignal' not allowed with QML property commands

This warning is specific to property group documentation. QDoc allows multiple qmlproperty or qmlattachedproperty topic commands in a single documentation comment to document a property group where the last element in the path is <group>.<property>. Any other topic commands triggers this warning.

## Cannot find base function for <method> in <class>

QDoc produces this warning if \reimp is used to document a method, as an override of a virtual method, when no base class has a virtual method with the given name and signature. This may happen because the method it was written to override has changed its signature, or is no longer virtual.

## Illegal \reimp; no documented virtual function for <command>

Qdoc tries to create a link to the function that this one reimplements, but it could not find the link target, likely because that function is not documented. This can also arise if no base class has a virtual method with this name and signature; which might arise due to a renaming, a change in signature or the base no longer declaring it virtual.

## <class> tries to inherit itself

The \inherits command is used to document that a QMl type inherits some other QML type. This warning is issued if that other QML type is the same as the QML type documented.

Example:

     \qmltype Foo
     \inherits Foo

## \nativetype is only allowed in \qmltype

The \nativetype command can only be used in a QDoc comment that documents a QML type.

## All properties in a group must belong to the same type: <name>

When documenting QML property groups, all properties listed in the comment block must belong to the same QML type.

## Cannot find project file for example <name>

In the example's source directory, QDoc expects to find a project file named `CMakeLists.txt`, or a file with a `.pro`, `.qmlproject`, or `.pyproject` extension where the base name matches that of the example directory. For example, `examples/mymodule/helloworld/helloworld.pro`.

## Cannot open file to quote from: <filename>

The search path for <filename> is defined by the following variables in the `.qdocconf` file: `sources`, `sourcedirs`, and `exampledirs`.

QDoc failed to find a file named in a command (such as \quotefromfile, \snippet, \include) that tells it to retrieve content from the named file. It searches each directory named in the search path. If there is no file with this name in any of those directories, or the file is found but not readable, QDoc issues this warning. Check that the combination of search path and <filename> is correctly spelled, and that you have read permissions for the file.

Note: <filename> may include a directory name prefix; the whole <filename> is appended to each directory in the search path.

## Missing format name after \raw

The \raw command and the corresponding \endraw command delimit a block of raw mark-up language code. The \raw command must be followed by the format name.

## Macro cannot have both format-specific and qdoc-syntax definitions

A \macro that specifies an output format cannot also have a generic definition.

An example of a configuration that triggers this warning:

     macro.gui = \b
     macro.gui.HTML = "<b>\1</b>"

## Unknown command <name>

When a QDoc comment uses a backslash followed by a token that is not a QDoc built-in command and has not been defined as a custom command macro, QDoc produces this warning. Check the spelling of the command name, and check whether your QDoc configuration doesn't include whatever would have defined it, if it's a custom command.

This may also be produced due to code being quoted in the QDoc comment, for example the author may have referred to the C string termination character `'\0'` or one of the other C string escape sequences such as `'\n'` without escaping the backslash. Escape the backslash as `\` to include a literal backslash in the documentation, or enclose the code fragment in `\c{...}`, which suppresses interpretation of backslashes as introducing QDoc commands.

## Duplicate target name <target>

This warning is issued if you define two targets with the same parameter, using either the \target or the \keyword command. The target name given as parameter to these commands must be unique. The warning is followed by "The previous occurrence is here: [location]", where location contains a file name and line number.

## Cannot find qdoc include file <filename>

QDoc failed to find an include file named in a command. QDoc searches each directory named in the search path. If there is no file with this name in any of those directories, or the file found in that search is not readable, QDoc issues this warning. Check that the combination of search path and <filename> is correctly spelled, and that you have read permissions for the file.

Note: <filename> may include a directory name prefix; the whole <filename> is appended to each directory in the search path.

## Cannot find <tag> in <file>

This means QDoc cannot find the identifier <id> in the \include <file> or {snippet-command}{\snippet} <file>.

## Empty qdoc snippet <tag> in <file>

The snippet <tag> was found in the \snippet <file>, but it is empty.

## Cannot nest <command> commands

This warning concerns formatting commands: bold, italic, index, link, span, subscript, superscript, teletype, uicontrol, underline. A formatting command cannot be used within the text it applies to. An example of this:

     There is \b{no \b{super-}bold}.
     \encode

     \section1 Can't use <inner> in <outer>

     This warning is issued for commands that cannot be nested.

     Example:
     \badcode
         \list
             \li \table
                 \row \li Hello \li Hi
                 \endtable
         \endlist

Results in the QDoc warning "Can't use '\table' in '\list'".

## Missing <outer> before <inner>

Some examples:

- The \li command can only be used inside a \list or a \row of a \table.
- The \row and \header commands can only be used within a \table.

## Unexpected <end_command>

This warning is issued if, for example, you have an \endlist without a preceding \list. It applies to all commands that come in pairs (e.g. startFoo/endFoo).

## Missing comma in \sa

The titles listed for a \sa command should be separated from one another with commas.

## Macro <command> does not have a default definition

QDoc is attempting to expand a macro, and expects that macro to have a default definition. Some macros may only have format-specific definitions.

Example:

     macro.pi.HTML = "&pi;"    # encodes the pi symbol for HTML output format

There are however instances where macro expansion requires a format-independent macro. For example, you can have macros in section titles, but they must have default definitions.

## Macro <macro> invoked with too few arguments (expected <many>, got <few>)

The given macro needs more parameters than it was given. See the definition of the macro in the configuration for further details.

## Unbalanced parentheses in <text>

Points to a '(' without a corresponding ')', or vice versa.

## No documentation for <name>

Example:

     Warning "No documentation for QNativeInterface."

QDoc detects the declaration of namespace QNativeInterface in a header file, but does not find a QDoc comment where that namespace has been documented.

## No such enum item <name> in <class>

Example:

     Cannot find 'QSGMaterialRhiShader::RenderState::DirtyState' specified
     with \enum in any header file.

QDoc issues this warning when it finds a \value directive in an \enum comment that names a value not found in the header file that declared the enumerated type documented.

## Undocumented enum item <enum> in <enum list>

<enum list>'s \value or \omitvalue entries did not include one for <enum>, which is named in the declaration of <enum list> in the header file.

## Failed to find qhp.<project>.subprojects.<subproject>.indexTitle

QDoc failed to find a title for a page designated as the index page for <subproject> in the Qt help project configuration.

Subproject index titles must be local to the current documentation project. Using a page title from another project, loaded as a dependency, also results in this warning.

For more information, see Creating Help Project Files.

## \generatelist <group> is empty

Below a short overview of all possible arguments for \generatelist:

- \generatelist annotatedexamples
- \generatelist annotatedattributions
- \generatelist classes <prefix>
- \generatelist classesbymodule <module name>
- \generatelist qmltypesbymodule <module name>
- \generatelist functionindex
- \generatelist legalese
- \generatelist overviews
- \generatelist attributions
- \generatelist related

QDoc issues this warning if you specify `\generatelist <group>` and the group does not contain any items, or if you specify `\generatelist <group> <pattern>` and no item in the group matches the pattern.

## \generatelist <group> no such group

This warning issues if the argument to \generatelist is a non-existing group.

Example:

     \generatelist draganddrop

This statement generates a list of classes or QML types in the draganddrop group. Classes or QML types are added to the draganddrop group by the `\l {ingroup-command}{\ingroup} draganddrop` command in their \class or \qmltype comment.

QDoc issues this warning message if no entity has this `\ingroup draganddrop` statement.

## Missing image: <imagefile>

The search path to the image is wrong, or the image file does not exist.

## Can't link to <target>

This can have a variety of causes:

- The link target has not been defined with a QDoc topic command, e.g. {title-command}{\title} <target>.
- The <target> contains a typo.
- The document that contains that link target did not get compiled.
- The document that contains that link target is in a module that is not in the compilation path.
- The link target is in another module, and a dependency to that module was not set in the configuration or QDoc failed to locate the index file for the dependency.

## Could not resolve QML import statement for type <name>

QDoc issues this warning if you document a QML type, but omit the \inqmlmodule command. Example:

     Could not resolve QML import statement for type 'ItemSelectionModel'
     \encode

     Incorrect:
       \badcode
       \qmltype ItemSelectionModel
       \nativetype QItemSelectionModel
       \since 5.5
       \ingroup qtquick-models

Correct:

     \qmltype ItemSelectionModel
     \nativetype QItemSelectionModel
     \inqmlmodule QtQml.Models
     \since 5.5
     \ingroup qtquick-models

## \brief statement does not end with a full stop

The argument to the \brief command is a sentence, summarizing the topic documented, so should end in a full stop. It should also be brief.

## QtDeclarative not installed; cannot parse QML

QDoc issues this warning if it has been compiled without support for QML parsing. This should not happen unless you have a custom build of QDoc.

## Invalid regular expression <regex>

Some QDoc commands take regular expressions as parameters. QDoc gives this warning when the text given as such a parameter is not a valid regular expression, usually due to it containing characters with special meanings in regular expressions, that should have been escaped.

Example:

     notifications.qdoc:56: (qdoc) warning: Invalid regular expression '^})$'

     \quotefromfile webenginewidgets/notifications/data/index.html
     \skipuntil resetPermission

Invalid regular expression:

     \printuntil /^})$/

Valid regular expression:

     \printuntil /^\}\)$/

The \printuntil command prints until it meets a line consisting of only a right curly brace followed by a right parenthesis. In this case, the curly brace and the parenthesis need to be escaped because they have special meanings in regular expressions.

## Multiple index files found for dependency <indexfile>:<depend>

Using <indexfile> as index file for dependency <depend>

Multiple `-indexdir` paths were passed to QDoc as command line options, and more than one contained an `.index` file that matches a dependency. QDoc picks the one with the latest timestamp automatically.

Typically, this warning indicates that there are build artifacts left from a previous documentation build.

## Cannot locate index file for dependency <depend>

Example:

     "QMake" Cannot locate index file for dependency "activeqt"

The documentation project QMake could not locate activeqt.index in any of the specified index directories. In this case, the specified index directories are specified in qmake.qdocconf.

## Dependent modules specified, but no index directories were set.

QDoc expected to see one or more -indexdir arguments on the command line. Without them, QDoc cannot locate the index files of any dependencies defined with the 'depends' configuration variable.

## Overrides a previous doc

QDoc issues this warning when it finds two comments that appear to describe the same entity. The location of the previously seen comment is provided in warning details.

## Unrecognized list style <name>

\list can take an optional argument: a single number or character that modifies the list style. Refer to the {list-command}{\list} documentation for more details. If you use an argument that is not recognized, QDoc issues this warning.

## Unable to parse QML snippet: <code> at line <y>, column <x>

QDoc comments can contain QML code. This code can be found in a snippet, or in the QDoc comments delimited by \qml and {endqml-command}{\endqml}.

Example:

If there is a syntax error in the QML code, QDoc issues the warning

     Unable to parse QML snippet: Syntax error at line 97, column 42

Snippets can also contain QML and also there the code is checked. If there is for example a missing curly brace in the code, QDoc issues the warning

     Unable to parse QML snippet: Expected token '{' at line 63, column 52

QDoc often fails to parse incomplete QML snippets; in these cases, it's often OK to replace the \qml ... \endqml commands with \code ... \endcode to suppress this warning.

## Command <command> failed at end of file <filename>

Example:

     Command "\snippet (//! [2]) failed at end of file qmlbars/qml/qmlbars/main.qml".

In this case the warning means that the \snippet command did not find a second label "//! [2]" to mark the end of the snippet. It could also mean that it didn't find any occurrence of that snippet tag in this snippet file.

Another example:

     Command '\skipto' failed at end of file 'styling/CMakeLists.txt".

The \skipto + <pattern> moves the cursor to the next line containing that pattern. If \skipto doesn't find it, QDoc issues this warning.

## Failed to open <file> for writing

This warning clearly means it cannot open a file for writing, probably because of a wrong path, or permission to write in a certain directory.

## This page title exists in more than one file

The \title command sets the title for a page.

     \page activeqt-server.html
     \title Building ActiveX servers in Qt

QDoc issues this warning if a certain title is used in more than one page.

## The content is too long

QDoc uses a fixed-size buffer when tokenizing source files. If any single token in the file has more characters than the maximum limit, QDoc issues this warning.

While QDoc continues parsing the file, only the part of the token that fits into the buffer is considered, meaning that the output might be mangled.

To resolve this warning, the relevant content must be reduced in size, either by splitting it, if possible, or by removing some of its parts.

The maximum amount of characters for a single token is shown alongside the warning, for example:

     file.qdoc:71154: (qdoc) warning: The content is too long.

     [The maximum amount of characters for this content is 524288.
     Consider splitting it or reducing its size.]

Note: Since content that is too long is not parsed in full, QDoc may issue warnings that are false positives. Resolve all warnings of this type before fixing other warnings.

## No documentation generated for function <name> in global scope

QDoc was able to match the documentation for a function <name> to its declaration, but no output was generated because the function is declared in the global namespace.

Use the \relates command to associate the function with a documented type, namespace, or a header file. The function is then listed as a related non-member on the associated reference page.

## Documentation configuration for <project> doesn't define a help project (qhp)

A valid Qt help configuration was expected but not provided in the project's .qdocconf file.

See also Creating Help Project Files and qhp.

## Already generated FILE for this project

While generating the documentation for a project, QDoc keeps track of the file names of the files it has generated. QDoc will issue a warning when it opens a file for writing if that file is known to have been generated previously, in the current execution. This can happen if a `\page` command uses the same name as `\group` for example.

You can set the environment variable `QDOC_ALL_OVERWRITES_ARE_WARNINGS` to unconditionally warn about all such events. This may be useful when tracking down the offending definitions.

## Invalid QML property type

The type used to declare a QML property was not a valid QML value type or QML object type, or it was a C++ or Qt type.

This warning typically occurs when developers refer to the underlying Qt type used to implement a QML type, such as QStringList instead of `list<string>`.

## Type is its own base type: <type>

The QML type has been incorrectly defined as its own base type, possibly using the \inherits command.

## Cyclic type inheritance: <type>

Cyclic or circular inheritance occurs when a QML type inherits from a base type that itself inherits from the original type. This can occur between two mutually inheriting types, or there may be intermediate types between them.

This warning indicates where a cycle in the inheritance hierarchy has been detected. You should examine the \inherits command for the type and follow the trail of base types until one is found that inherits from a type that you have previously encountered. You should then break the cycle by fixing the incorrect \inherits command for one of the identified types.

## Redundant link to self in \sa command for <name>

A piece of documentation contains a link to itself in the references defined in its \sa command.

This problem tends to occur when there is a collection of related properties or methods that refer to each other, and where the \sa commands have been copied between them, as in this example:

     \fn void Items::append(const Item &)
     ...
     \sa append(), count(), insert(), remove()

It is useful to replace the self-referencing link with one to another related property or method.

Alternatively, the link may not be specific enough for QDoc to resolve, as in this example:

     \fn void MyPicture::setSize(int)
     ...
     \sa setSize()

In this case, the intention may have been to refer to an overload that accepts a `double` argument:

     \fn void MyPicture::setSize(int)
     ...
     \sa setSize(double)

## Unknown base <name> for QML type <type>

The type name declared as the base type for a QML type was not found, or it was not declared with the \inherits command.

See also Cannot find qdoc include file <filename> and Cannot open file to quote from: <filename>.

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