If an error occurs in *spliced* code, it can be tricky to understand
what is going on. With this patch, in
- epxressions
- types
we give a helpful indicator that it's in the result of a splice.
For declarations it's harder, because they get type-checked in a
group with other non-spliced decls, so I have not made the same improvement.
But it's still better than it was.
-- Rename it, but bale out if there are errors
-- otherwise the type checker just gives more spurious errors
-- Rename it, but bale out if there are errors
-- otherwise the type checker just gives more spurious errors
- ; (exp3, _fvs) <- checkNoErrs (rnLExpr expr2)
+ ; addErrCtxt (spliceResultDoc expr) $ do
+ { (exp3, _fvs) <- checkNoErrs (rnLExpr expr2)
- ; exp4 <- tcMonoExpr exp3 res_ty
- ; return (unLoc exp4) }
+ ; exp4 <- tcMonoExpr exp3 res_ty
+ ; return (unLoc exp4) } }
+
+spliceResultDoc :: LHsExpr Name -> SDoc
+spliceResultDoc expr
+ = sep [ ptext (sLit "In the result of the splice:")
+ , nest 2 (char '$' <> pprParendExpr expr)
+ , ptext (sLit "To see what the splice expanded to, use -ddump-splices")]
-------------------
tcTopSpliceExpr :: TcM (LHsExpr Id) -> TcM (LHsExpr Id)
-------------------
tcTopSpliceExpr :: TcM (LHsExpr Id) -> TcM (LHsExpr Id)
-- Rename it, but bale out if there are errors
-- otherwise the type checker just gives more spurious errors
-- Rename it, but bale out if there are errors
-- otherwise the type checker just gives more spurious errors
- ; let doc = ptext (sLit "In the spliced type") <+> ppr hs_ty2
+ ; addErrCtxt (spliceResultDoc expr) $ do
+ { let doc = ptext (sLit "In the spliced type") <+> ppr hs_ty2
; hs_ty3 <- checkNoErrs (rnLHsType doc hs_ty2)
; hs_ty3 <- checkNoErrs (rnLHsType doc hs_ty2)
; (ty4, kind) <- kcLHsType hs_ty3
; (ty4, kind) <- kcLHsType hs_ty3
- ; return (unLoc ty4, kind) }
+ ; return (unLoc ty4, kind) }}
\end{code}
%************************************************************************
\end{code}
%************************************************************************