Is it possible to prevent omission of aggregate initialization members?
For clang and gcc you can compile with -Werror=missing-field-initializers
that turns the warning on missing field initializers to an error. godbolt
Edit: For MSVC, there seems to be no warning emitted even at level /Wall
, so I don't think it is possible to warn on missing initializers with this compiler. godbolt
Here is a trick which triggers a linker error if a required initializer is missing:
struct init_required_t {
template <class T>
operator T() const; // Left undefined
} static const init_required;
Usage:
struct Foo {
int bar = init_required;
};
int main() {
Foo f;
}
Outcome:
/tmp/ccxwN7Pn.o: In function `Foo::Foo()':
prog.cc:(.text._ZN3FooC2Ev[_ZN3FooC5Ev]+0x12): undefined reference to `init_required_t::operator int<int>() const'
collect2: error: ld returned 1 exit status
Caveats:
- Prior to C++14, this prevents
Foo
from being an aggregate at all. - This technically relies on undefined behaviour (ODR violation), but should work on any sane platform.