[PATCH] D39284: [c++2a] Decomposed _condition_

Zhihao Yuan via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Wed Oct 25 12:59:44 PDT 2017

lichray added a comment.

In https://reviews.llvm.org/D39284#906899, @aaron.ballman wrote:

> We typically diagnose vendor extensions to the language, and I think we should apply that consistently. Otherwise, your code will compile fine in Clang with warning levels cranked all the way up and then fail to compile on every other compiler, which does not do our users any good. I'll let Richard have the final say for this, but my preference is that this is diagnosed as an extension (at least in pedantic mode).

I think we don't have a practice to issue diagnosis for a change that is basically racing with the standard.  First, if we issue a diagnosis now, there is a chance for the (coming) proposal to be accepted before we making a release from trunk; second, users are supposed to be cautious using latest `-std=` in general, as there might be coming fixes.  In addition, this change, most of the time, requires the users to opt-in by providing conversion operators, so users are expected to be intentionally trying it out rather than accidentally running into a situation that you describe.

But anyway, ping @rsmith?


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