[project @ 1999-12-03 00:03:06 by lewie]

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

diff --git a/ghc/compiler/typecheck/TcBinds.lhs b/ghc/compiler/typecheck/TcBinds.lhs
index 6a64ece..55c37dd 100644 (file)
--- a/ghc/compiler/typecheck/TcBinds.lhs
+++ b/ghc/compiler/typecheck/TcBinds.lhs
@@ -28,6 +28,7 @@ import TcEnv          ( tcExtendLocalValEnv,
                          tcGetGlobalTyVars, tcExtendGlobalTyVars
                        )
 import TcSimplify      ( tcSimplify, tcSimplifyAndCheck, tcSimplifyToDicts )
+import TcImprove       ( tcImprove )
 import TcMonoType      ( tcHsType, checkSigTyVars,
                          TcSigInfo(..), tcTySig, maybeSig, sigCtxt
                        )
@@ -250,6 +251,14 @@ tcBindWithSigs top_lvl mbind tc_ty_sigs inline_sigs is_rec
        -- (must do this before getTyVarsToGen)
     checkSigMatch top_lvl binder_names mono_ids tc_ty_sigs     `thenTc` \ maybe_sig_theta ->   
 
+       -- IMPROVE the LIE
+       -- Force any unifications dictated by functional dependencies.
+       -- Because unification may happen, it's important that this step
+       -- come before:
+       --   - computing vars over which to quantify
+       --   - zonking the generalized type vars
+    tcImprove lie_req `thenTc_`
+
        -- COMPUTE VARIABLES OVER WHICH TO QUANTIFY, namely tyvars_to_gen
        -- The tyvars_not_to_gen are free in the environment, and hence
        -- candidates for generalisation, but sometimes the monomorphism