Accessing 'Annotations' of modules in external packages

[Christiaan Baaij]

ghc-devs is probably a better location for GHC API questions.

Anyhow, you might want to look at some code in the Clash compiler:
https://github.com/clash-lang/clash-compiler/blob/6ec3ca426bfaaaddcd3692775c25614bc19482fa/clash-ghc/src-ghc/Clash/GHC/LoadInterfaceFiles.hs#L168-L225
We use that to find the following annotations in compiled packages:
http://hackage.haskell.org/package/clash-prelude-0.99/docs/Clash-Annotations-Primitive.html

Anyhow, the gist of:
https://github.com/clash-lang/clash-compiler/blob/6ec3ca426bfaaaddcd3692775c25614bc19482fa/clash-ghc/src-ghc/Clash/GHC/LoadInterfaceFiles.hs#L168-L225
is:

* You need a `Module` to start with (you can e.g. get one from a `CoreBndr`)
* You need to load the interface file (.hi) for that module.
* One you have the contents of the interface file, you can do
`TcIface.tcIfaceAnnotations (GHC.mi_anns iface)` to get something of the
`Annotation` type.

Hope that helps.

-- Christiaan

On 18 April 2018 at 23:01, Ranjit Jhala <jhala at cs.ucsd.edu> wrote:

>
> Hi all,
>
> I'm looking for some help using the GHC API to
>
> access the 'Annotations' (created using the 'ANN'
>
> mechanism) within modules of *external* packages
>
> i.e. non-home modules.Currently I'm using
>
>   hscEPS :: HscEnv -> IO ExternalPackageState
>
> and then using the field
>
>   eps_PIT :: !PackageIfaceTable
>
> and from there, accessing the
>
>   mi_anns :: [IfaceAnnotation]
>
> field of the
>
>   data ModIface
>
> stored in the PackageIfaceTable but this ends in an unfortunate:
>
> ```
> panic! (the 'impossible' happened)
>   (GHC version 8.2.2 for x86_64-apple-darwin):
>     No mi_anns in PIT
>
> Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
> ```
>
> Perhaps this is because, as the documentation for `mi_anns` says:
>
>    Annotations NOT STRICT! we read this field lazily from the interface
> file
>
> but I am not sure how to proceed at this point? Do I need a _different_
> HscEnv? Or perhaps I need to set up/initialize the HscEnv separately?
>
> Any pointers would be most welcome!
>
> Thanks!
>
> Ranjit.
>
>
>
>
>
>
>
> _______________________________________________
> Glasgow-haskell-users mailing list
> Glasgow-haskell-users at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/ghc-devs/attachments/20180420/d2af88b3/attachment.html>