🚀 go-pugleaf

kanze@lts.sel.alcatel.de (James Kanze US/ESC 60/3/141 #40763) writes:

>fjh@munta.cs.mu.OZ.AU (Fergus Henderson) writes:
>
>|> clamage@Eng.Sun.COM (Steve Clamage) writes:
>
>|> >According the draft standard, the results of using a reference
>|> >type as the last pararmeter before the ellipsis (...) are
>|> >undefined. See section 18.7 "Other runtime support" [lib.support.runtime].
>
>|> Is there any good reason why this has undefined behaviour rather than
>|> being ill-formed code?  Surely this should be very easy for
>|> implementations to detect and diagnose.
>
>Hysterica^H^H^H^H^H^H^Horical reasons, no doubt.  Declare the last
>parameter a char in C, and you also get undefined behavior.
>
>And it's surely no more difficult to diagnose a double underscore (and
>at least one compiler does), which is also `undefined behavior'.

No, I think providing useful diagnostics for use of references before
an elipsis is indeed less difficult than providing useful diagnostics
for use of double underscores.  It's difficult (though by no means
impossible, of course) for implementations to issue diagnostics for
uses of the implementation's part of the namespace without also issuing
diagnostics for definitions in the system header files or in code which
merely references macros defined in the system header files.

--
Fergus Henderson <fjh@cs.mu.oz.au>   |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>   |  of excellence is a lethal habit"
PGP: finger fjh@128.250.37.3         |     -- the last words of T. S. Garp.
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