Mistake in C++ ABI substitution rules?

[Joe Buck]

> > "Logically, the substitutable components of a mangled name are
> > considered left-to-right, components before the composite structure
> > of which they are a part. If a component has been encountered
> > before, it is substituted as described below. This decision is
> > independent of whether its components have been substituted,
> > so an implementation MAY OPTIMIZE by considering large structures
> > for substitution before their components. If a component has not
> > been encountered before, its mangling is identified, and it is
> > added to a dictionary of substitution candidates. No entity is
> > added to the dictionary twice." (emphasis mine)

Mark writes:
> I think that "may" should be "must".

If all the folks who implemented the ABI interpreted it that way, we
have no problem with s/may/must/.  But if some did not, then we don't
have a portable ABI, someone will have to make changes.