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<body><span class="vcard"><a class="email" href="mailto:dberlin@dberlin.org" title="Daniel Berlin <dberlin@dberlin.org>"> <span class="fn">Daniel Berlin</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - LLVM's Global Value Numbering pass bug"
href="https://llvm.org/bugs/show_bug.cgi?id=30550">bug 30550</a>
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<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>
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<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>INVALID
</td>
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - LLVM's Global Value Numbering pass bug"
href="https://llvm.org/bugs/show_bug.cgi?id=30550#c2">Comment # 2</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - LLVM's Global Value Numbering pass bug"
href="https://llvm.org/bugs/show_bug.cgi?id=30550">bug 30550</a>
from <span class="vcard"><a class="email" href="mailto:dberlin@dberlin.org" title="Daniel Berlin <dberlin@dberlin.org>"> <span class="fn">Daniel Berlin</span></a>
</span></b>
<pre>First, note:
/Users/dannyb/Downloads/test (1).cpp:38:23: warning: when type is in
parentheses, array cannot have dynamic
size
p1 = new (20) (char[i]);
~ ^ ~
/Users/dannyb/Downloads/test (1).cpp:39:23: warning: when type is in
parentheses, array cannot have dynamic
size
p2 = new (20) (char[i]);
~ ^ ~
2 warnings generated.
Clang's warning is correct here:
"With the parentheses, the type to be newed comes from a type-id, in this case
char[i]. This is a variable length array which is not standard behavior.
Without the parentheses, the type to be newed is a new-type-id, an array of X."
g++ will give you the same warning:
/Users/dannyb/Downloads/test (1).cpp: In function 'int tst()':
/Users/dannyb/Downloads/test (1).cpp:38:25: warning: non-constant array new
length must be specified without parentheses around the type-id [-Wvla]
p1 = new (20) (char[i]);
^
/Users/dannyb/Downloads/test (1).cpp:39:25: warning: non-constant array new
length must be specified without parentheses around the type-id [-Wvla]
p2 = new (20) (char[i]);
^
Second, these functions overwrite the heap (and thus, i'm not sure why you
believe they have to return 0).
Both g++ and clang with -fsanitize=address will show you this.
This is because you have:
int i = 0;
p1 = new (20) char[i];
Regardless of what your allocation function does, you've told it you've got a
dynamic array of size 0 :)
If you change the code to
p1 = new (20) char[20];
p2 = new (20) char[20];
or
int i = 20
p1 = new (20) char[i];
p2 = new (20) char[i];
It will succeed in all cases.
Marking as invalid for now.</pre>
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