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Subject: Re: [Boost-users] [MSM] state transitions and exceptions
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2012-04-05 00:14:15


On 04/04/2012 06:07 PM, Dave Abrahams wrote:
> Plus, the way the language is defined, ordering is very important.
> There's a point of definition and various points of instantiation...
> particular lookups are done in those locations, and the symbol table has
> to be right in each case, at least with respect to the symbols used in
> the template. I doubt it's easy to unwind those dependencies.


"If the function name is an unqualified id and the call ...
would find a better match had the lookup within the associated
namespaces considered all the function declarations with
external linkage introduced within those namespaces in
all translation units, not just considering those declarations
found in the template declaration and template instantiation
contexts, then the program has undefined behavior." (

"If a template, a member template, or a member of a class
template is explicitly specialized, then the specialization
shall be declared before the first use of that specialization
that would cause an implicit instantiation to take place...
no diagnostic is required" (14.7.3)
(There is a similar clause for partial specialization)

In other words, it seems to me that in most cases where
delaying the point of instantiation would change the
behavior it is either undefined behavior or ill-formed,
no diagnostic required.

In Christ,
Steven Watanabe

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