<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><span class="vcard"><a class="email" href="mailto:richard-llvm@metafoo.co.uk" title="Richard Smith <richard-llvm@metafoo.co.uk>"> <span class="fn">Richard Smith</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - Unexpected constexpr assignment error relating to object lifetime and std::allocator"
href="https://bugs.llvm.org/show_bug.cgi?id=47047">bug 47047</a>
<br>
<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
<tr>
<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
</td>
</tr>
<tr>
<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>INVALID
</td>
</tr></table>
<p>
<div>
<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - Unexpected constexpr assignment error relating to object lifetime and std::allocator"
href="https://bugs.llvm.org/show_bug.cgi?id=47047#c1">Comment # 1</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - Unexpected constexpr assignment error relating to object lifetime and std::allocator"
href="https://bugs.llvm.org/show_bug.cgi?id=47047">bug 47047</a>
from <span class="vcard"><a class="email" href="mailto:richard-llvm@metafoo.co.uk" title="Richard Smith <richard-llvm@metafoo.co.uk>"> <span class="fn">Richard Smith</span></a>
</span></b>
<pre>Your testcase has undefined behavior; GCC is wrong to accept it.
std::allocator<int>::allocate only allocates memory for the array of ints, it
does not start the lifetime of any int objects. You need to create an int
object using std::construct_at before you can assign to it:
std::allocator<int> alloc;
int *p = alloc.allocate(1);
std::construct_at(p);
*p = 42;
int i = *p;
alloc.deallocate(p,1);
Then GCC and Clang both accept: <a href="https://godbolt.org/z/8j9Kas">https://godbolt.org/z/8j9Kas</a></pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>