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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - "no viable conversion" error in brace initialization, compiles using assignment (g++ compiles both)"
href="https://llvm.org/bugs/show_bug.cgi?id=30461">30461</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>"no viable conversion" error in brace initialization, compiles using assignment (g++ compiles both)
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>3.8
</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++11
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>jamespharvey20@gmail.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>Arch Linux
clang++ version 3.8.1 (tags/RELEASE_381/final)
Target: x86_64-unknown-linux-gnu
... Selected GCC installation: /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/6.2.1
Using "g++ --std=c++11", this code compiles and prints "Hello".
==========
#include <string>
#include <iostream>
using namespace std;
class someClass {
public:
operator const string() const { return "Hello"; }
};
int main() {
someClass something;
string str { something }; /* Generates an error using clang++ */
cout << str << endl;
}
==========
Using "clang++ --std=c++11", this code fails compilation:
==========
clangNoViableConversion.cpp:12:17: error: no viable conversion from 'someClass'
to 'std::__cxx11::basic_string<char>'
string str { something };
^~~~~~~~~
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/6.2.1/../../../../include/c++/6.2.1/bits/basic_string.h:397:7:
note: candidate
constructor not viable: no known conversion from 'someClass' to 'const
std::__cxx11::basic_string<char> &' for 1st
argument
basic_string(const basic_string& __str)
^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/6.2.1/../../../../include/c++/6.2.1/bits/basic_string.h:454:7:
note: candidate
constructor not viable: no known conversion from 'someClass' to 'const
char *' for 1st argument
basic_string(const _CharT* __s, const _Alloc& __a = _Alloc())
^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/6.2.1/../../../../include/c++/6.2.1/bits/basic_string.h:476:7:
note: candidate
constructor not viable: no known conversion from 'someClass' to
'std::__cxx11::basic_string<char> &&' for 1st argument
basic_string(basic_string&& __str) noexcept
^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/6.2.1/../../../../include/c++/6.2.1/bits/basic_string.h:503:7:
note: candidate
constructor not viable: no known conversion from 'someClass' to
'initializer_list<char>' for 1st argument
basic_string(initializer_list<_CharT> __l, const _Alloc& __a = _Alloc())
^
clangNoViableConversion.cpp:7:7: note: candidate function
operator const string() const { return "Hello"; }
^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/6.2.1/../../../../include/c++/6.2.1/bits/basic_string.h:476:35:
note: passing
argument to parameter '__str' here
basic_string(basic_string&& __str) noexcept
^
1 error generated.
==========
Changing the offending line from
==========
string str { something };
==========
to
==========
string str = something;
==========
Makes clang++ compile a working program.</pre>
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