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/6ec3ca426bfaaaddcd3692775c... We use that to find the following annotations in compiled packages: http://hackage.haskell.org/package/clash-prelude-0.99/docs/Clash-Annotations... Anyhow, the gist of: https://github.com/clash-lang/clash-compiler/blob/6ec3ca426bfaaaddcd3692775c... 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 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.

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