RFR: 8292671: Hotspot Style Guide should allow covariant returns

[Roland Westrelin]

On Fri, 19 Aug 2022 14:12:05 GMT, Roland Westrelin <roland at openjdk.org> wrote:

> The style guide explicitly lists covariant returns as a disallowed
> feature of c++. I propose we allow that feature.
> 
> This came up on the c2 side where, with JDK-8275201, I introduced some
> uses of covariant returns at a number of locations in the c2 code
> because I felt the code was cleaner that way. I wasn't aware it was
> mentioned on the style guide. This was noticed by another openjdk
> contributor and I prepared a change to revert the use of covariant
> returns I had introduced:
> 
> https://github.com/openjdk/jdk/pull/9237
> 
> But it feels that change actually makes the code less clear and
> comments on the PR indicates some other contributors feel the same
> way.
> 
> It's unclear to me why covariant returns are disallowed in the first
> place and the (few) contributors I asked don't seem to know either. So
> I propose simply allowing covariant returns.

Thanks for the reviews

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PR: https://git.openjdk.org/jdk/pull/9941