RFR: 7903612: Nested struct typedefs fail to compile [v2]

[Maurizio Cimadamore]

On Fri, 15 Dec 2023 10:26:19 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> This PR fixes a small issue with nested struct typedef, and another with typedef in general:
>> 
>> * nested struct classes are emitted with the `final` modifier, which prevents them from being subclassed (e.g. in typedefs)
>> * all structs have a private constructor to prevent clients from instantiating. Unfortunately this constructor also prevents subclassing (e.g. in typedef).
>> 
>> This patch drops the `final` modifier on nested struct/unions, and also tweaks the default constructor from `private` to `protected`.
>
> Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add missing copyright

test/jtreg/generator/packed/TestPackedStructs.java line 36:

> 34:  * @test id=classes
> 35:  * @library /lib
> 36:  * @run main/othervm JtregJextract -t test.jextract.packedstructs packedstructs.h

This is an unrelated change: I just noted that this `-l` flag was not needed

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PR Review Comment: https://git.openjdk.org/jextract/pull/164#discussion_r1427811953