Infinity + Infinity (or NegInfinity - NegInfinity)

[Tim Rentsch]

So in what respect is that incompatible with IEEE 754? C specifies
not only that in (a+b)+c, a+b happens first, but that in a+b+c,
a+b happens first, so it's more prescriptive than Fortran.

You are clearly a revisionist, as well as being unfamiliar with the
ISO/ANSI C standards and their implementations!

There is no such statement in the C standard, and I can tell you
(from personal recollection) that requiring it was NOT WG14's intent
during the standardisation of C90. The BNF was intended to specify
ONLY the precedence of operators and NOT the evaluation order; [snip]

The BNF does specify the order of evaluation (for values)
for any two subexpressions where one is contained in the
other, just not for subexpressions neither of which contains
the other. (Of course with the understanding that side
effects are a whole other story.)