Fix TH erorr recovery (test is TH_recover)

[ghc-hetmet.git] / compiler / typecheck / TcBinds.lhs

diff --git a/compiler/typecheck/TcBinds.lhs b/compiler/typecheck/TcBinds.lhs
index cffcb9c..e71d920 100644 (file)
--- a/compiler/typecheck/TcBinds.lhs
+++ b/compiler/typecheck/TcBinds.lhs
@@ -173,6 +173,11 @@ tcValBinds top_lvl (ValBindsOut binds sigs) thing_inside
              ; sig_fn  = mkSigFun ty_sigs }
 
        ; poly_ids <- mapM tcTySig ty_sigs
+               -- No recovery from bad signatures, because the type sigs
+               -- may bind type variables, so proceeding without them
+               -- can lead to a cascade of errors
+               -- ToDo: this means we fall over immediately if any type sig
+               -- is wrong, which is over-conservative, see Trac bug #745
 
                -- Extend the envt right away with all 
                -- the Ids declared with type signatures