[foreign-jextract] RFR: 8249536: jextract throw IllegalStateException for bitfields in nested anonymous structs

[Paul Sandoz]

On Wed, 15 Jul 2020 16:22:09 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

> Hi,
> 
> This patch fixes an issue with grouping of bitfields into a container for structs that contain anonymous nested structs
> that have bitfields in them. Such as
> struct Foo {
>     struct {
>         int a : 7;
>         int b : 25;
>     };
> };
> 
> The current code iterates over the member layouts of a struct, and when it finds a bitfield storage unit, it tries to
> find matching bitfield Declarations and groups them into a synthetic nested BITFIELDS declaration.
> But, the memory layout members also contain bitfields that are found in anonymous nested structs, since they are
> flattened into the parent layout. However, for the jextract Declaration tree this is not the case, so the current code
> can not find a matching declaration for these bitfield layouts. e.g. in the example `Foo` will have a bitfield storage
> unit which contains `a` and `b`, but the Declaration tree has the declarations for `a` and `b` nested inside the
> anonymous struct (layouts and declaration tree are different in this regard).  The fix is to ignore bitfields that come
> from nested anonymous structs. They will be handled when processing the nested anonymous struct instead.  Thanks, Jorn

What happens for the following?
struct Foo {
    struct {
        int a : 7;
        int b : 25;
    };
    struct Bar {
	int a : 12;
    } bar;
};

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PR: https://git.openjdk.java.net/panama-foreign/pull/246