RFR: 7903485 Windows.h fails to extract on jextract/panama [v2]

[Jorn Vernee]

On Mon, 12 Jun 2023 12:12:47 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> This patch fixes a number of issues I discovered while trying to extract Windows.h on a recent jextract:
>> 
>> * the size of `long double` layout is wrong. This means that if a struct with a field of that type is declared, StructLayoutComputer will fail (as it will see a size != expected size reported by clang)
>> * There are cases where, also for unsupported layouts, we end up creating function descriptors with things containing padding. This is caused by the fact that the check for unsupported layouts in functions is performed *after* the creation of the function descriptor.
>> * Sometimes libclang reports field cursors in an out-of-order fashion. I have not been able to pinpoint the exact cause, as all my attempts to create a reduced test case failed. When this behavior occurs, jextract ends up generating extra fields and padding. I believe this behavior has always been there, but now brought to the fore by the new eager checks.
>> * A change in behavior of recent libclang causes `cursor.spelling()` to return non-empty strings (see https://github.com/llvm/llvm-project/issues/58429)
>> * A quality of life fix, to generate "sensible" warnings when variadic callbacks are found
>
> Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Address review comments

Marked as reviewed by jvernee (Committer).

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PR Review: https://git.openjdk.org/jextract/pull/122#pullrequestreview-1474850337