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<body><span class="vcard"><a class="email" href="mailto:rnk@google.com" title="Reid Kleckner <rnk@google.com>"> <span class="fn">Reid Kleckner</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - "extern template" seems to invoke explicit instanciation but it should prohibit it."
href="http://llvm.org/bugs/show_bug.cgi?id=20825">bug 20825</a>
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<th>What</th>
<th>Removed</th>
<th>Added</th>
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<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
</td>
</tr>
<tr>
<td style="text-align:right;">CC</td>
<td>
</td>
<td>rnk@google.com
</td>
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<tr>
<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>INVALID
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - "extern template" seems to invoke explicit instanciation but it should prohibit it."
href="http://llvm.org/bugs/show_bug.cgi?id=20825#c1">Comment # 1</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - "extern template" seems to invoke explicit instanciation but it should prohibit it."
href="http://llvm.org/bugs/show_bug.cgi?id=20825">bug 20825</a>
from <span class="vcard"><a class="email" href="mailto:rnk@google.com" title="Reid Kleckner <rnk@google.com>"> <span class="fn">Reid Kleckner</span></a>
</span></b>
<pre>I think you can forward declare your specialization of the static data member
like so:
// Start .h
template <typename T> class A {
public:
static const char *info;
};
template <> const char *A<int>::info;
template <> const char *A<char>::info;
extern template class A<int>;
extern template class A<char>;
// Start .cpp
#include <iostream>
template <> const char *A<int>::info = "This is int";
template <> const char *A<char>::info = "This is char";
int main(int, char **) {
std::cout << "A<int>:" << A<int>::info << "\n";
std::cout << "A<char>:" << A<char>::info << "\n";
return 0;
}
template class A<int>;
template class A<char>;
----
Otherwise, the compiler can do things like inline the generic, unspecialized
version of an inline function into your program. Consider:
template <typename T>
struct A { static int f() { return sizeof(int); } };
extern template struct A<int>;
int main() {
return A<int>::f();
}
After optimizations, main will return 4, even if some other TU contains:
template <> int A<int>::f() { return 5; };
This specialization can be similarly forward declared as:
template <> int A<int>::f();</pre>
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