https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104512
Bug ID: 104512
Summary: [c++20] consteval constructor does not need to
initialize all data members
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fchelnokov at gmail dot com
Target Milestone: ---
In the next program struct B has immediate consteval default constructor, which
does not initialize i field. Then this constructor is used to make a temporary
and its i field remains untouched:
```
struct B {
bool b = true;
int i;
consteval B() {}
};
static_assert( B{}.b );
```
Clang and MSVC are fine with it. But GCC complains:
error: 'B{true}' is not a constant expression
7 | static_assert( B{}.b );
| ^
error: 'B()' is not a constant expression because it refers to an incompletely
initialized variable
Demo: https://gcc.godbolt.org/z/x4n6ezrhT
The requirement that "every non-variant non-static data member must be
initialized" in constexpr/consteval constructor is removed since c++20. Related
discussion: https://stackoverflow.com/a/71085832/7325599
