CStub in inline-java

[Facundo Domínguez]

Dear devs,

I upgraded inline-java [1] to use GHC 9.10.2 recently. inline-java has a
GHC plugin responsible for embedding JVM bytecode in Haskell modules. This
message is to consult on the most appropriate way to do it.

The byte code is placed in a C literal array of bytes, and the C code is
added in mg_foreign together with C constructor functions that run when
loading the module to add the bytecode to a global bytecode table [2]. The
global bytecode table is then fed to the JVM when initializing inline-java.

The GHC API in 9.10.2 requires creating a CStub which does have a field to
indicate constructor functions [3], but I wouldn't know how to create the
CLabels it needs. So instead, I just put the constructor functions in the
getCStub field, and set getInitializers to an empty list. The constructor
functions seem to run at initialization just the same.

Should inline-java do this differently?

Thanks in advance!
Facundo

[1] https://github.com/tweag/inline-java
[2]
https://github.com/tweag/inline-java/blob/c6b590c29ef9190164dec3a235b8e386c537bd29/src/Language/Java/Inline/Plugin.hs#L87
[3]
https://gitlab.haskell.org/ghc/ghc/-/blob/3c37d30b07fc85fe09452f4ce250aec42cb1d2e4/compiler/GHC/Types/ForeignStubs.hs#L23

data CStub = CStub { getCStub :: SDoc
                   , getInitializers :: [CLabel]
                     -- ^ Initializers to be run at startup
                     -- See Note [Initializers and finalizers in Cmm] in
                     -- "GHC.Cmm.InitFini".
                   , getFinalizers :: [CLabel]
                     -- ^ Finalizers to be run at shutdown
                   }

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