https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109387
Bug ID: 109387
Summary: "definition of explicitly-defaulted" error with
explicit template instantiation
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: vittorio.romeo at outlook dot com
Target Milestone: ---
Given this code:
template <typename> struct S { S(); };
// extern template struct S<int>;
template <typename T> S<T>::S() = default;
template S<int>::S();
GCC fails to compile with this error:
error: definition of explicitly-defaulted 'S< <template-parameter-1-1>
>::S()
[with <template-parameter-1-1> = int]'
3 | template <typename T> S<T>::S() = default;
| ^~~~
Uncommenting the extern template fixes compilation. Clang compiles the original
code without any issue.
Live example on Compiler Explorer:
- https://gcc.godbolt.org/z/YoPhvKnxa
Related StackOverflow thread:
- https://stackoverflow.com/questions/75913223
