[cfe-dev] implementing clone for ASTNodes

[Gaetano Checinski via cfe-dev]

I was wondering if anybody spend some efforts in implementing a clone
Method for all ASTNodes?

It seems to me, that the current approach implemented in the ASTImporter is
error-prone and hard to maintain.

Currently it looks to me that Decls / Stmt's are being probed for their
type and then downcasted, eg.:

/* ASTNodeImporter::VisitExplicitCastExpr */
/* ASTImporter.cpp:6060 */
switch (E->getStmtClass()) {
  case Stmt::CStyleCastExprClass: {
     CStyleCastExpr *CCE = cast<CStyleCastExpr>(E);
     return CStyleCastExpr::Create(Importer.getToContext(), T,
        E->getValueKind(), E->getCastKind(),
        SubExpr, &BasePath, TInfo,
        Importer.Import(CCE->getLParenLoc()),
        Importer.Import(CCE->getRParenLoc()));
}
/* more cases*/



As the AST contains circular references and many nodes require an ASTContext
for construction, i'm wondering how feasible it would be to implement the
following interface for each Decl?

 virtual Decl* clone(
   ASTContext* newContext,
   DenseMap<Decl*, Decl*> ImportedDeclsCache = {}
 );








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