[Issue 19841] Wrong ABI for C++ functions taking a struct by value

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19841

--- Comment #6 from Walter Bright <bugzilla at digitalmars.com> ---
D's definition of POD is:

1. it is not nested
2. it has no postblits, destructors, or assignment operators
3. it has no ref fields or fields that are themselves non-POD

https://dlang.org/spec/struct.html#POD

C++'s definition is quite a bit more complicated, and changes from one version
of the Standard to another:

https://stackoverflow.com/questions/4178175/what-are-aggregates-and-pods-and-how-why-are-they-special/7189821#7189821

For reference, "the equivalent C++ code" is:

struct Foo {
    char _[32];
};

struct Bar {
    Bar(Foo foo);
};

void oops() {
    auto foo = Foo();
    auto bar = Bar(foo);
}

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