Re: Language extension / "behavior"

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On Tue, 24 Jan 2023 10:47:49 +0100, Didier Verna said:

Section 1.6 Language Extensions of the standard says this:

A language extension is any documented implementation-defined behavior of a defined name in this standard that varies from the behavior described in this standard [...]

It is unclear to me if the term "behavior" could encompass additional keyword arguments passed to a function or macro.

I think it does, because section 3.5.1.4 Unrecognized Keyword Arguments says that an error must be signaled for unrecognized keywords in a safe call, so that will not happen for an extension keyword.