ctest: detect improper field types

[tgross35]

I thought we had a check for this but I guess not, given that #1020 doesn't seem to present any errors. This kind of check would be very helpful there.

E.g. for this input:

struct foo {
    int a;
};

Produce something like this test:

void check_foo_a(struct foo test_foo) {
    long test_foo_a_0 = test_foo.a;
    long *test_foo_a_1 = &test_foo.a;
}

The _1 test comparing pointers is the important bit here since it should catch -Wincompatible-pointer-types. I don't know if the _0 test will catch anything that doesn't, but it doesn't hurt.

This test can be created for both structs and unions.

[tgross35]

@mbyx any chance you're still around? This should be a reasonably easy ctest thing if you're up for it.

[mbyx]

Yes, I'll try to finish it off by the weekend.

Although I'm a bit confused by the example. There's two types, in the example, int is the actual type used by the original C code, and long would be the type that the Rust code translated into? So it checks if there is a mismatch between them, if there is it would trigger -Wincompatible-pointer-types and fail.

This should be doable for simple types at least.

[tgross35]

Yeah sorry, didn't clarify in the example; int would be the correct type, long would be an incorrect type and is just what I was using to make sure it catches mismatched integers that wouldn't be caught just by value.