[foreign-jextract] Integrated: 8251256: jextrac code generated for nested structs, unions is incorrect

[Maurizio Cimadamore]

On Thu, 6 Aug 2020 17:39:46 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> This patch rectifies the behavior of jextract with respect to nested structs and/or unions.
> 
> More specifically, jextract failed to recursively generate interfaces for anonymous structs and unioins; this led to a
> situation (as described in the JBS issue) where the only operation a client can do is to retrieve a segment for the
> nested struct/union, but all nested accessors are not available.  The fix allows jextract to recurse; more
> specifically, if a struct/union field type is itself an anonymous struct/union, the interface for the anonymous
> struct/union will be generated (nested inside the current struct interface).  So, in the example submitted in the JBS
> issue, it would be possible to poke at the nested union field, as follows:
>  MemorySegment rdma = ibv_send_wr.wr$addr(someSegment);
>  ibv_send_wr.wr.rdma.remote_addr$get(rdma);
> 
> Note the nesting: `ibv_send_wr.wr.rdma` where:
> 
> * `ibv_send_wr` is the enclosing struct declaration
> * `wr` is the union declaration, nested inside the struct
> * `rdma` is a struct that is one of the union alternatives
> 
> To make the code more uniform, I've reworked JavaSourceBuilder a little - more specifically:
> 
> * JavaSourceBuilder is aware of the fact that builders can *nest* into each other
> * Rather than dumping contents of a child builder into the parent, we use delegation, to make sure that all calls to
>   `append` eventually hit the `StringBuilder` in the toplevel builder --- effectively removing the need to copy
> * each builder has its own name context (to fixup duplicate names); this follows from the fact that each nested class
>   introduces a fresh scope, so no clashes with names defined outside are possible
> 
> While I've added no test, I found out that an existing test (Test8244512) was already triggering the scenario described
> in the JBS issue. I've tweaked the test to take into account the fact that now jextract correctly nests inner structs,
> as well as the fact that jextract is now adding interfaces even for the anon structs/union attached to struct/union
> fields.

This pull request has now been integrated.

Changeset: 48b684eb
Author:    Maurizio Cimadamore <mcimadamore at openjdk.org>
URL:       https://git.openjdk.java.net/panama-foreign/commit/48b684eb
Stats:     330 lines in 6 files changed: 40 ins; 123 del; 167 mod

8251256: jextrac code generated for nested structs, unions is incorrect

Reviewed-by: sundar

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PR: https://git.openjdk.java.net/panama-foreign/pull/280