.hie files don't contain template Haskell splices

Motivation

I want to use the new .hie files to do full-project reachability analysis. Given some roots (e.g., main in module Main), the program will report any declarations that aren't reachable from those roots, thus identifying them as dead code. I do this by traversing HieASTs and building a graph of which symbols refer to which. However, Template Haskell splices aren't expanded, so if something is referred to from a splice, it won't cause that node to be correctly represented in the reachability graph.

One example of this is Yesod - we have the splice mkYesodDispatch "App" resourcesApp, which creates a YesodDispatch instance for App:

src/AppMain.hs:80:1-34: Splicing declarations
    mkYesodDispatch "App" resourcesApp
  ======>
    instance YesodDispatch App where
      yesodDispatch env6176_a1vQg req6176_a1vQh
        = helper6176_a1vQi (pathInfo req6176_a1vQh)
        where
            helper6176_a1vQi ((:) "robots.txt" [])
              = case requestMethod req6176_a1vQh of
                  "GET"
                    -> (((yesodRunner getRobotTxtR) env6176_a1vQg) (Just RobotTxtR))
                         req6176_a1vQh
                  _ -> (((yesodRunner (void badMethod)) env6176_a1vQg)
                          (Just RobotTxtR))
                         req6176_a1vQh

However, the .hie file doesn't contain all of this information, it only contains the instance head. ppHie reports:

Node src/AppMain.hs:80:1-34 [(AbsBinds, HsBindLR),
                             (ClsInstD, InstDecl), (FunBind, HsBindLR), (HsApp, HsExpr),
                             (HsAppTy, HsType), (HsConLikeOut, HsExpr), (HsTyVar, HsType),
                             (HsVar, HsExpr), (HsWrap, HsExpr), (VarBind, HsBindLR)] [53, 58,
                                                                                      55,
                                                                                      66] [(Right C:YesodDispatch,
                                                                                            IdentifierDetails Nothing {Use}),
                                                                                           (Right yesodDispatch,
                                                                                            IdentifierDetails Nothing {ValBind InstanceBind ModuleScope (Just SrcSpanOneLine "src/AppMain.hs" 80 1 35)}),
                                                                                           (Right yesodDispatch,
                                                                                            IdentifierDetails Just 55 {ValBind RegularBind ModuleScope (Just SrcSpanOneLine "src/AppMain.hs" 80 1 35)}),
                                                                                           (Right $cyesodDispatch,
                                                                                            IdentifierDetails Just 55 {Use}),
                                                                                           (Right $cp1YesodDispatch,
                                                                                            IdentifierDetails Just 53 {Use})]

and that's it. Thus the symbols referred to in the definition of yesodDispatch aren't visible to me.

Proposal

The full instance declaration is visible.