https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65896
Bug ID: 65896
Summary: Erroneous uninitialized variable access error in
constexpr function with temporary variables
Product: gcc
Version: 5.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: david at doublewise dot net
Target Milestone: ---
file.cpp
==================================================
struct base{};
struct derived : base {
constexpr derived():
base{},
m_value(0) {
}
constexpr derived(derived & other):
base{},
m_value(other) {
}
constexpr explicit operator int() const {
return m_value;
}
int m_value;
};
constexpr int by_ref(derived && value) {
return (derived(value), 0);
}
constexpr int value = by_ref(derived{});
==================================================
c++ -std=c++11 -o /dev/null file.cpp -c
gcc 4.8.3 and 4.9.3 and clang 3.5.0 successfully compile this program. gcc
5.1.1 fails with:
file.cpp:22:29: in constexpr expansion of ‘by_ref(derived())’
file.cpp:22:39: in constexpr expansion of ‘derived((* & value))’
file.cpp:10:16: in constexpr expansion of ‘(& other)->derived::operator
int()’
file.cpp:22:39: error: accessing uninitialized member ‘derived::m_value’
constexpr int value = by_ref(derived{});
^
Changing to C++1y / C++14 does not change this.
