https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125563
Bug ID: 125563
Summary: GCC accepts a default argument that invokes a deleted
constructor in a class template
Product: gcc
Version: 15.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: qurong at ios dot ac.cn
Target Milestone: ---
GCC 15.2.0 accepts the following program in -std=c++20, including with
-pedantic-errors:
struct X {
X() = delete;
};
template <int>
struct O {
struct I {
I(const X& = X());
};
};
template struct O<2>;
Clang 22 rejects the same code with:
error: call to deleted constructor of 'X'
Commands
g++ -std=c++20 -pedantic-errors -c test.cpp
clang++ -std=c++20 -pedantic-errors -c test.cpp
Actual behavior
GCC 15.2.0: accepts
Clang 22.0.0: rejects
Expected behavior
The program should be rejected, because the default argument X() attempts to
call a deleted constructor.
