QDoc: Remove `CppCodeParser::topicCommands`

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 some of the `CodeParser` child classes provides
series of methods to retrieve the required commands for each parser.

`CppCodeParser`, the parser that provides the semantic for QDoc's
comment-blocks, for example, provides `topicCommands`, to list the
available "topic commands" in a commnet-block.

`topicCommands` initializes a static member, `topicCommands_` 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 `topicCommands_`,
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 `topicCommands_`, 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 `topicCommands()` method is removed, along with
`topicCommands_`, in favor of a public static,
`topic_commands`, that is initialized in-place, to simplify the
related code.

All usages of `topicCommands` were modified to refer to
`CppCodeParser::topic_commands`, keeping an equivalent semantic, as a
consequence of the change.

Change-Id: I9de2332bf557254e7ffd33290e6af678c2b121aa
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/qdoc/clangcodeparser.cpp b/src/qdoc/clangcodeparser.cpp
index 5bf7a7521..b9aa27fbe 100644
--- a/src/qdoc/clangcodeparser.cpp
+++ b/src/qdoc/clangcodeparser.cpp
@@ -1563,7 +1563,7 @@ void ClangCodeParser::parseSourceFile(const Location & /*location*/, const QStri
 
     CXToken *tokens;
     unsigned int numTokens = 0;
-    const QSet<QString> &commands = topicCommands() + metaCommands();
+    const QSet<QString> &commands = CppCodeParser::topic_commands + metaCommands();
     clang_tokenize(tu, clang_getCursorExtent(tuCur), &tokens, &numTokens);
 
     for (unsigned int i = 0; i < numTokens; ++i) {
@@ -1579,7 +1579,7 @@ void ClangCodeParser::parseSourceFile(const Location & /*location*/, const QStri
         Doc::trimCStyleComment(loc, comment);
 
         // Doc constructor parses the comment.
-        Doc doc(loc, end_loc, comment, commands, topicCommands());
+        Doc doc(loc, end_loc, comment, commands, CppCodeParser::topic_commands);
         if (hasTooManyTopics(doc))
             continue;