std::ffi::VaList does not match esp_idf_sys::va_list

[jothan]

I tried this code:

extern "C" {
    fn vsnprintf(s: *mut c_char, n: usize, format: *const c_char, ap: VaList) -> c_int;
}

Calling the above function with this signature crashes.

Instead, replacing VaList with VaListImpl works.

extern "C" {
    fn vsnprintf(s: *mut c_char, n: usize, format: *const c_char, ap: VaListImpl) -> c_int;
}

The underlying issue seems that VaList should contain 3 u32 fields instead of being single pointer sized.

Details in PR #238

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rustc --version --verbose:

rustc 1.81.0-nightly (02368e90f 2024-09-03) (1.81.0.0)
binary: rustc
commit-hash: 02368e90f28c216258b47072a65cb6b4991fc0ed
commit-date: 2024-09-03
host: x86_64-unknown-linux-gnu
release: 1.81.0-nightly
LLVM version: 17.0.1