[Bug c++/115851] ICE in gimplify_var_or_parm_decl with coroutine suspension point inside statement expression

[daklishch at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115851

--- Comment #1 from Dan Klishch <daklishch at gmail dot com> ---
GCC seems to do checks for coroutine-related types more eagerly now, so the
original minified reproducer is rejected. Nonetheless, the underlying issue
persists, which can be shown using this snippet:

```
#include <coroutine>

struct SuspendNever {
    bool await_ready();
    void await_suspend(std::coroutine_handle<>);
    void await_resume();
};

struct Coroutine;

struct PromiseType {
    Coroutine get_return_object();
    SuspendNever initial_suspend();
    SuspendNever final_suspend();
};

struct Coroutine {
    using promise_type = PromiseType;
};

struct ErrorOr {
    int release_error();
};

void warnln(int const&);

Coroutine __async_test_input_basic() {
    ({
        co_await SuspendNever{};
        ErrorOr _temporary_result2;
        warnln(_temporary_result2.release_error());
    });
}
```

CE link: https://godbolt.org/z/aG588Whv6