QDoc: Remove `CodeParser::commonMetaCommands`

As part of extracting user-provided documentation, QDoc has to parse a
variety of source files in a variety of languages.

`CodeParser` is the base class of objects that take care of performing
this parsing process in QDoc.

When extracting the documentation in one of the `CodeParser`s QDoc
generally tries to parse the extracted documentation in-place.

The documentation has a series of available commands that might depend
on the currently used parser.
To support this process `CodeParser` provides as part of its interface a
series of methods to retrieve the required commands for each parser.

One of those methods, `commonMetaCommands`, provides the commands that
are common to all parser.

`commonMetaCommands` initializes a static member, `commonMetaCommands_`
and then returns it, avoiding initialization if the method is called
more than once.

While this process can be better expressed by the simple use of a
`static` there are two probable reason for why it wasn't done in this
way.

Supposedly, when this code was written, there was no suitable way to
initialize a `QSet<QString>`, the type of `commonMetaCommands_`,
in-place, as similar patterns can be found in other legacy parts of QDoc
that are confirmed to have had this issue due to their age.

Additionally, the expansion of the `COMMAND_*` macros, which form the
content for `commonMetaCommands_`, were, until recently, dependent on
certain data being available in another part of the system, so that
expanding them in a static context that would be processed before this
data was available would incur into a series of errors.
This dependency was removed in a recent patch, so that the issue is no
more.

Hence, the `commonMetaCommands()` method is removed, along with
`commonMetaCommands_`, in favor of a public static,
`common_meta_commands`, that is initialized in-place, to simplify the
related code.

`common_meta_commands` is initialized inline under `CodeParser` in
"codeparser.h".
Its initialization depends on the `COMMAND_*` macros being available.
Previously, those macros were defined under `Codeparser` in
"codeparser.h" so that they would not be available at the point of
initialization.

Hence, all definition of the `COMMAND_*` macros were moved higher up in
"codeparser.h", to ensure that they would be available when required by
`common_meta_commands`.

All usages of `commonMetaCommands()` were modified to refer to
`CodeParser::common_meta_commands`, keeping an equivalent semantic.

Change-Id: If4987e5c1b53e80585e7556e62701690d98954c3
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>

4 files changed, 50 insertions, 61 deletions

diff --git a/src/qdoc/codeparser.cpp b/src/qdoc/codeparser.cpp
index 65ee08353..77c7d0f24 100644
--- a/src/qdoc/codeparser.cpp
+++ b/src/qdoc/codeparser.cpp
@@ -84,27 +84,6 @@ CodeParser *CodeParser::parserForSourceFile(const QString &filePath)
     return nullptr;
 }
 
-static QSet<QString> commonMetaCommands_;
-/*!
-  Returns the set of strings representing the common metacommands.
- */
-const QSet<QString> &CodeParser::commonMetaCommands()
-{
-    if (commonMetaCommands_.isEmpty()) {
-        commonMetaCommands_ << COMMAND_ABSTRACT << COMMAND_DEFAULT << COMMAND_DEPRECATED
-                            << COMMAND_INGROUP << COMMAND_INMODULE << COMMAND_INPUBLICGROUP
-                            << COMMAND_INQMLMODULE << COMMAND_INTERNAL << COMMAND_MODULESTATE
-                            << COMMAND_NOAUTOLIST << COMMAND_NONREENTRANT << COMMAND_OBSOLETE
-                            << COMMAND_PRELIMINARY << COMMAND_QMLABSTRACT << COMMAND_QMLDEFAULT
-                            << COMMAND_QMLINHERITS << COMMAND_QMLREADONLY << COMMAND_QMLREQUIRED
-                            << COMMAND_QTCMAKEPACKAGE << COMMAND_QTVARIABLE << COMMAND_REENTRANT
-                            << COMMAND_SINCE << COMMAND_STARTPAGE  << COMMAND_SUBTITLE
-                            << COMMAND_THREADSAFE << COMMAND_TITLE << COMMAND_WRAPPER
-                            << COMMAND_ATTRIBUTION;
-    }
-    return commonMetaCommands_;
-}
-
 /*!
   \internal
  */
diff --git a/src/qdoc/codeparser.h b/src/qdoc/codeparser.h
index 08e06449d..304e83993 100644
--- a/src/qdoc/codeparser.h
+++ b/src/qdoc/codeparser.h
@@ -10,44 +10,6 @@
 
 QT_BEGIN_NAMESPACE
 
-class Location;
-class QString;
-class QDocDatabase;
-
-class CodeParser
-{
-public:
-    CodeParser();
-    virtual ~CodeParser();
-
-    virtual void initializeParser() = 0;
-    virtual void terminateParser();
-    virtual QString language() = 0;
-    virtual QStringList sourceFileNameFilter() = 0;
-    virtual void parseSourceFile(const Location &location, const QString &filePath) = 0;
-    virtual Node *parseFnArg(const Location &, const QString &, const QString & = QString())
-    {
-        return nullptr;
-    }
-
-    void checkModuleInclusion(Node *n);
-
-    static void initialize();
-    static void terminate();
-    static CodeParser *parserForLanguage(const QString &language);
-    static CodeParser *parserForSourceFile(const QString &filePath);
-    static void setLink(Node *node, Node::LinkType linkType, const QString &arg);
-    static bool isWorthWarningAbout(const Doc &doc);
-
-protected:
-    const QSet<QString> &commonMetaCommands();
-    static void extractPageLinkAndDesc(QStringView arg, QString *link, QString *desc);
-    QDocDatabase *m_qdb {};
-
-private:
-    static QList<CodeParser *> s_parsers;
-};
-
 #define COMMAND_ABSTRACT QLatin1String("abstract")
 #define COMMAND_CLASS QLatin1String("class")
 #define COMMAND_DEFAULT QLatin1String("default")
@@ -117,6 +79,54 @@ private:
 // deprecated alias of qmlvaluetype
 #define COMMAND_QMLBASICTYPE QLatin1String("qmlbasictype")
 
+class Location;
+class QString;
+class QDocDatabase;
+
+class CodeParser
+{
+public:
+    static inline const QSet<QString> common_meta_commands{
+        COMMAND_ABSTRACT, COMMAND_DEFAULT, COMMAND_DEPRECATED, COMMAND_INGROUP,
+        COMMAND_INMODULE, COMMAND_INPUBLICGROUP, COMMAND_INQMLMODULE, COMMAND_INTERNAL,
+        COMMAND_MODULESTATE, COMMAND_NOAUTOLIST, COMMAND_NONREENTRANT, COMMAND_OBSOLETE,
+        COMMAND_PRELIMINARY, COMMAND_QMLABSTRACT, COMMAND_QMLDEFAULT, COMMAND_QMLINHERITS,
+        COMMAND_QMLREADONLY, COMMAND_QMLREQUIRED, COMMAND_QTCMAKEPACKAGE, COMMAND_QTVARIABLE,
+        COMMAND_REENTRANT, COMMAND_SINCE, COMMAND_STARTPAGE, COMMAND_SUBTITLE, COMMAND_THREADSAFE,
+        COMMAND_TITLE, COMMAND_WRAPPER, COMMAND_ATTRIBUTION,
+    };
+
+public:
+    CodeParser();
+    virtual ~CodeParser();
+
+    virtual void initializeParser() = 0;
+    virtual void terminateParser();
+    virtual QString language() = 0;
+    virtual QStringList sourceFileNameFilter() = 0;
+    virtual void parseSourceFile(const Location &location, const QString &filePath) = 0;
+    virtual Node *parseFnArg(const Location &, const QString &, const QString & = QString())
+    {
+        return nullptr;
+    }
+
+    void checkModuleInclusion(Node *n);
+
+    static void initialize();
+    static void terminate();
+    static CodeParser *parserForLanguage(const QString &language);
+    static CodeParser *parserForSourceFile(const QString &filePath);
+    static void setLink(Node *node, Node::LinkType linkType, const QString &arg);
+    static bool isWorthWarningAbout(const Doc &doc);
+
+protected:
+    static void extractPageLinkAndDesc(QStringView arg, QString *link, QString *desc);
+    QDocDatabase *m_qdb {};
+
+private:
+    static QList<CodeParser *> s_parsers;
+};
+
 QT_END_NAMESPACE
 
 #endif
diff --git a/src/qdoc/cppcodeparser.cpp b/src/qdoc/cppcodeparser.cpp
index 0f0cfe1cf..01434f352 100644
--- a/src/qdoc/cppcodeparser.cpp
+++ b/src/qdoc/cppcodeparser.cpp
@@ -77,7 +77,7 @@ CppCodeParser::CppCodeParser()
                        << COMMAND_STRUCT << COMMAND_UNION;
     }
     if (metaCommands_.isEmpty()) {
-        metaCommands_ = commonMetaCommands();
+        metaCommands_ = CodeParser::common_meta_commands;
         metaCommands_ << COMMAND_INHEADERFILE << COMMAND_NEXTPAGE
                       << COMMAND_OVERLOAD << COMMAND_PREVIOUSPAGE << COMMAND_QMLINSTANTIATES
                       << COMMAND_REIMP << COMMAND_RELATES;
diff --git a/src/qdoc/qmlcodeparser.cpp b/src/qdoc/qmlcodeparser.cpp
index e851a2ebd..ce8ddce72 100644
--- a/src/qdoc/qmlcodeparser.cpp
+++ b/src/qdoc/qmlcodeparser.cpp
@@ -79,7 +79,7 @@ void QmlCodeParser::parseSourceFile(const Location &location, const QString &fil
 
     if (m_parser->parse()) {
         QQmlJS::AST::UiProgram *ast = m_parser->ast();
-        QmlDocVisitor visitor(filePath, newCode, &m_engine, topicCommands() + commonMetaCommands(),
+        QmlDocVisitor visitor(filePath, newCode, &m_engine, topicCommands() + CodeParser::common_meta_commands,
                               topicCommands());
         QQmlJS::AST::Node::accept(ast, &visitor);
         if (visitor.hasError())