[PATCH] D31153: Add the ability to use the children() range API in a const-correct manner

[David Blaikie via cfe-commits]

On Tue, Apr 11, 2017 at 10:27 AM Aaron Ballman via Phabricator <
reviews at reviews.llvm.org> wrote:

> aaron.ballman added inline comments.
>
>
> ================
> Comment at: include/clang/AST/Expr.h:4025
>    child_range children() {
> +    const_child_range CCR = const_cast<const InitListExpr
> *>(this)->children();
> +    return child_range(cast_away_const(CCR.begin()),
> ----------------
> dblaikie wrote:
> > If this is adding const, can you use a weaker cast? (I guess what would
> be ideal here would be implicit_cast - if you're interested you could add
> that - otherwise... yeah, I guess static_cast could do other nasty things,
> etc, so there's nothing good)
> I'm not certain what you mean. This is adding the const qualifier so that
> we call the proper overload. I'm not certain of what a weaker cast would be.
>

Oh, I meant something like tihs:
http://www.boost.org/doc/libs/1_39_0/boost/implicit_cast.hp
<http://www.boost.org/doc/libs/1_39_0/boost/implicit_cast.hpp>p

The thing about using a const_cast to add const is it can be a bit hard to
read/be sure about. I don't know if it's removing some const while it adds
other const.


>
>
> ================
> Comment at: include/clang/AST/StmtIterator.h:148-150
> +inline StmtIterator cast_away_const(const ConstStmtIterator &RHS) {
> +  return RHS;
> +}
> ----------------
> dblaikie wrote:
> > Maybe I'm missing something - what stops code from doing this conversion
> implicitly/accidentally all over the place? (I would've expecetd
> cast_away_const to be a friend or something, to only allow the conversion
> through this explicit call/operation)
> Good catch, I've corrected this.
>
>
> https://reviews.llvm.org/D31153
>
>
>
>
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