QDoc: Move `CodeParser::precompileHeaders` to `ClangCodeParser`

QDoc parses a series of source file in different languages and formats
to find the user-provided documentation.

The base parsing interface for elements that perform this process is
given by the `CodeParser` class, with the concrete implementation of the
process for different languages/formats give by its child classes.

`CodeParser`, as part of its interface, provides certain methods that
are only meaningful when processing specific programming languages
source.

For example, it exposes `CodeParser::precompileHeaders` whose purpose it
to provide a PCH for parsing C++ source files.

The method is only implemented and used in the `ClangCodeParser` child
class, the class that actually implements the processing of C++ source
files.

Hence, the method is now removed from `CodeParser`'s interface and
directly exposed as part of the interface of `ClangCodeParser`, to
reduce the surface of the method and to reduce the dependencies between
`ClangCodeParser` and the `CodeParser` interface, which is generally
expected to be removed in the future.

Change-Id: I243b81974c741589e7f644e1996cdb274e20502b
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>

2 files changed, 1 insertions, 2 deletions

diff --git a/src/qdoc/clangcodeparser.h b/src/qdoc/clangcodeparser.h
index 3aa2f9a79..30d639f9f 100644
--- a/src/qdoc/clangcodeparser.h
+++ b/src/qdoc/clangcodeparser.h
@@ -24,7 +24,7 @@ public:
     QStringList sourceFileNameFilter() override;
     void parseHeaderFile(const Location &location, const QString &filePath) override;
     void parseSourceFile(const Location &location, const QString &filePath) override;
-    void precompileHeaders() override;
+    void precompileHeaders();
     Node *parseFnArg(const Location &location, const QString &fnSignature, const QString &idTag) override;
     static const QByteArray &fn() { return s_fn; }
 
diff --git a/src/qdoc/codeparser.h b/src/qdoc/codeparser.h
index 76d9daf10..ebd433dae 100644
--- a/src/qdoc/codeparser.h
+++ b/src/qdoc/codeparser.h
@@ -27,7 +27,6 @@ public:
     virtual QStringList sourceFileNameFilter() = 0;
     virtual void parseHeaderFile(const Location &location, const QString &filePath);
     virtual void parseSourceFile(const Location &location, const QString &filePath) = 0;
-    virtual void precompileHeaders() {}
     virtual Node *parseFnArg(const Location &, const QString &, const QString & = QString())
     {
         return nullptr;