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>

1 files changed, 1 insertions, 1 deletions

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;