https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38265
Geoff Romer <gromer at google dot com> changed:
What |Removed |Added
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CC| |gromer at google dot com
--- Comment #14 from Geoff Romer <gromer at google dot com> ---
> The C++11 standard clarifies that this is intended to work. The range
> constructors require the type to be EmplaceConstructible into the container
> from the iterator's value_type
But see [sequence.reqmts]/p3: "i and j denote iterators satisfying input
iterator requirements and refer to elements implicitly convertible to
value_type". So this is not "intended to work" per se; a conforming library
could disallow it. However, the notes on LWG 536 say "Some support, not
universal, for respecting the explicit qualifier", so it looks like the
standard intentionally permits this as a conforming extension.
In principle, I think "perfect initialization" is what's called for here: the
range ctor should be explicit if and only if it uses an explicit constructor
for value_type. However, I doubt it's worth the trouble (OTOH, it definitely
will be worth the trouble when/if we get single-argument range constructors).
