<html>
<head>
<base href="https://llvm.org/bugs/" />
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Incorrect mangling and linking with C++ language linkage"
href="https://llvm.org/bugs/show_bug.cgi?id=27549">27549</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Incorrect mangling and linking with C++ language linkage
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>C++
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>julien.cretin@trust-in-soft.com
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>According to my reading of the N3376 draft of the C++11 standard,
"C++" should be the default language linkage. As such, assuming a
well-defined program, I would expect the behavior to be the same
whether a global variable with external linkage is declared as
`extern` or as `extern "C++"`.
N3376:7.5:1: [...] The default language linkage of all function types,
function names, and variable names is C++ language linkage. [...]
% cat m.cpp
extern "C++" int x;
int main(void) { return x; }
% cat x.cpp
extern "C++" int x;
int x = 1;
% clang++ m.cpp x.cpp
/tmp/m-2fcd74.o: In function `main':
m.cpp:(.text+0xe): undefined reference to `x'
clang-3.9: error: linker command failed with exit code 1 (use -v to see
invocation)
% clang++ -c m.cpp; nm m.o
U _Z1x
0000000000000000 T main
% clang++ -c x.cpp; nm x.o
0000000000000000 D x
% g++ m.cpp x.cpp
% g++ -c m.cpp; nm m.o
0000000000000000 T main
U x
% g++ -c x.cpp; nm x.o
0000000000000000 D x
% cat n.cpp
extern int x;
int main(void) { return x; }
% clang++ n.cpp x.cpp
%
The issue seems related to the mangling of global variables with
C++ language linkage, which is not coherent with the mangling of
global variables without language linkage.</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>