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<body><span class="vcard"><a class="email" href="mailto:mclow.lists@gmail.com" title="Marshall Clow (home) <mclow.lists@gmail.com>"> <span class="fn">Marshall Clow (home)</span></a>
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<a class="bz_bug_link
bz_status_RESOLVED bz_closed" title="RESOLVED INVALID - vector of const - push_back fail" href="https://urldefense.proofpoint.com/v2/url?u=https-3A__llvm.org_bugs_show-5Fbug.cgi-3Fid-3D23852&d=AwMBaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=pF93YEPyB-J_PERP4DUZOJDzFVX5ZQ57vQk33wu0vio&m=RYxfXIWvQmEd7j-WorLvuKB8TS5tCTvULT-fR9SuTYc&s=r0yd9iK-NMK8IztNE7o--9gVXYapzMp8I0eZYL-AhYM&e=">bug 23852</a>
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<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
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<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
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<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>INVALID
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<td style="text-align:right;">Assignee</td>
<td>unassignedclangbugs@nondot.org
</td>
<td>mclow.lists@gmail.com
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed" title="RESOLVED INVALID - vector of const - push_back fail" href="https://urldefense.proofpoint.com/v2/url?u=https-3A__llvm.org_bugs_show-5Fbug.cgi-3Fid-3D23852-23c1&d=AwMBaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=pF93YEPyB-J_PERP4DUZOJDzFVX5ZQ57vQk33wu0vio&m=RYxfXIWvQmEd7j-WorLvuKB8TS5tCTvULT-fR9SuTYc&s=WG2ieTdAs9NYQ8cIG1dZFr72-_efDBrl-RYDY2RZIKc&e=">Comment # 1</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed" title="RESOLVED INVALID - vector of const - push_back fail" href="https://urldefense.proofpoint.com/v2/url?u=https-3A__llvm.org_bugs_show-5Fbug.cgi-3Fid-3D23852&d=AwMBaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=pF93YEPyB-J_PERP4DUZOJDzFVX5ZQ57vQk33wu0vio&m=RYxfXIWvQmEd7j-WorLvuKB8TS5tCTvULT-fR9SuTYc&s=r0yd9iK-NMK8IztNE7o--9gVXYapzMp8I0eZYL-AhYM&e=">bug 23852</a>
from <span class="vcard"><a class="email" href="mailto:mclow.lists@gmail.com" title="Marshall Clow (home) <mclow.lists@gmail.com>"> <span class="fn">Marshall Clow (home)</span></a>
</span></b>
<pre>The standard says the requirement for push_back is that the value type (T) of a
vector needs to be "T shall be CopyInsertable into X." (where X is the
container) [Table 100]
What does that mean? [23.2.1/15] says:
Given a container type X having an allocator_type identical to A and a
value_type identical to T and given an lvalue m of type A, a pointer p of type
T*, an expression v of type (possibly const) T ...
(skip ahead to p15.4)
T is CopyInsertable into X means that, in addition to T being MoveInsertable
into X, the following expression is well-formed:
allocator_traits<A>::construct(m, p, v)
and its evaluation causes the following postcondition to hold: The value of v
is unchanged and is equivalent to *p.
So, it needs to be able to this:
std::allocator<const int> a;
const int *p;
int v = 17;
std::allocator_traits<std::allocator<const int>>::construct(m, p, v);
but p is a pointer to const int - and so the allocator cannot construct a new
int there.
Hence, the compile failure.
In general, containers of const types is a bad idea.</pre>
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