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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - clang incorrectly rejects constexpr constructor which modified member variable in its body"
href="http://llvm.org/bugs/show_bug.cgi?id=19741">19741</a>
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<th>Summary</th>
<td>clang incorrectly rejects constexpr constructor which modified member variable in its body
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>3.4
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>C++1y
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>ytj000@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>struct A {
int a = 0;
constexpr A() { a = 1; }
};
constexpr bool f() {
constexpr A a;
static_assert(a.a == 1, ""); // L1: OK
return a.a == 1;
}
static_assert(f(), ""); // L2: Error, can not modify A::a in constexpr
- Online Compiler URL: <a href="http://goo.gl/jni6Em">http://goo.gl/jni6Em</a>
- Compiler: clang 3.4 (with -std=c++1y)
- System: Linux 3.2
The constructor satisfies all the conditions listed in ยง7.1.5/4 of N3936.
However, clang complains:
clang++ -stdlib=libc++ -std=c++1y a.cpp -c -o a.o -Wall
a.cpp:11:15: error: static_assert expression is not an integral constant
expression
static_assert(f(), ""); // L2: Error
^~~
a.cpp:3:23: note: modification of object of const-qualified type 'const int' is
not allowed in a constant expression
constexpr A() { a = 1; }
^
a.cpp:7:17: note: in call to 'A()'
constexpr A a;
^
a.cpp:11:15: note: in call to 'f()'
static_assert(f(), ""); // L2: Error
^
1 error generated.</pre>
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