[commit: ghc] wip/T11371: Change the warning in substTy back to an assertion (736cebd)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : wip/T11371
Link       : http://ghc.haskell.org/trac/ghc/changeset/736cebde2b716498a0a5e63af9d7f9a45c1b8495/ghc

>---------------------------------------------------------------

commit 736cebde2b716498a0a5e63af9d7f9a45c1b8495
Author: Krzysztof Gogolewski <krzysztof.gogolewski at tweag.io>
Date:   Thu Mar 7 17:19:45 2019 +0100

    Change the warning in substTy back to an assertion
    
    We'd like to enforce the substitution invariant (Trac #11371).
    In a492af06d326453 the assertion was downgraded to a warning;
    I'm restoring the assertion and making the calls that
    don't maintain the invariant as unchecked.


>---------------------------------------------------------------

736cebde2b716498a0a5e63af9d7f9a45c1b8495
 compiler/coreSyn/CoreArity.hs       | 2 +-
 compiler/typecheck/TcGenGenerics.hs | 2 +-
 compiler/typecheck/TcSigs.hs        | 2 +-
 compiler/types/TyCoRep.hs           | 5 ++---
 4 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/compiler/coreSyn/CoreArity.hs b/compiler/coreSyn/CoreArity.hs
index 37454eb..afd6759 100644
--- a/compiler/coreSyn/CoreArity.hs
+++ b/compiler/coreSyn/CoreArity.hs
@@ -1153,7 +1153,7 @@ freshEtaId :: Int -> TCvSubst -> Type -> (TCvSubst, Id)
 freshEtaId n subst ty
       = (subst', eta_id')
       where
-        ty'     = Type.substTy subst ty
+        ty'     = Type.substTyUnchecked subst ty
         eta_id' = uniqAway (getTCvInScope subst) $
                   mkSysLocalOrCoVar (fsLit "eta") (mkBuiltinUnique n) ty'
         subst'  = extendTCvInScope subst eta_id'
diff --git a/compiler/typecheck/TcGenGenerics.hs b/compiler/typecheck/TcGenGenerics.hs
index abc7d59..123cfd3 100644
--- a/compiler/typecheck/TcGenGenerics.hs
+++ b/compiler/typecheck/TcGenGenerics.hs
@@ -431,7 +431,7 @@ tc_mkRepFamInsts gk tycon inst_tys =
            env        = zipTyEnv env_tyvars env_inst_args
            in_scope   = mkInScopeSet (tyCoVarsOfTypes inst_tys)
            subst      = mkTvSubst in_scope env
-           repTy'     = substTy  subst repTy
+           repTy'     = substTyUnchecked  subst repTy
            tcv'       = tyCoVarsOfTypeList inst_ty
            (tv', cv') = partition isTyVar tcv'
            tvs'       = scopedSort tv'
diff --git a/compiler/typecheck/TcSigs.hs b/compiler/typecheck/TcSigs.hs
index 9146b10..7b00165 100644
--- a/compiler/typecheck/TcSigs.hs
+++ b/compiler/typecheck/TcSigs.hs
@@ -505,7 +505,7 @@ tcInstSig hs_sig@(PartialSig { psig_hs_ty = hs_ty
                              , sig_inst_wcs   = wcs
                              , sig_inst_wcx   = wcx
                              , sig_inst_theta = substTys subst theta
-                             , sig_inst_tau   = substTy  subst tau }
+                             , sig_inst_tau   = substTyUnchecked  subst tau }
        ; traceTc "End partial sig }" (ppr inst_sig)
        ; return inst_sig }
 
diff --git a/compiler/types/TyCoRep.hs b/compiler/types/TyCoRep.hs
index 9ccfaae..27fde88 100644
--- a/compiler/types/TyCoRep.hs
+++ b/compiler/types/TyCoRep.hs
@@ -3196,8 +3196,7 @@ isValidTCvSubst (TCvSubst in_scope tenv cenv) =
 -- Note [The substitution invariant].
 checkValidSubst :: HasCallStack => TCvSubst -> [Type] -> [Coercion] -> a -> a
 checkValidSubst subst@(TCvSubst in_scope tenv cenv) tys cos a
--- TODO (RAE): Change back to ASSERT
-  = WARN( not (isValidTCvSubst subst),
+  = ASSERT2( isValidTCvSubst subst,
              text "in_scope" <+> ppr in_scope $$
              text "tenv" <+> ppr tenv $$
              text "tenvFVs" <+> ppr (tyCoVarsOfTypesSet tenv) $$
@@ -3205,7 +3204,7 @@ checkValidSubst subst@(TCvSubst in_scope tenv cenv) tys cos a
              text "cenvFVs" <+> ppr (tyCoVarsOfCosSet cenv) $$
              text "tys" <+> ppr tys $$
              text "cos" <+> ppr cos )
-    WARN( not tysCosFVsInScope,
+    ASSERT2( tysCosFVsInScope,
              text "in_scope" <+> ppr in_scope $$
              text "tenv" <+> ppr tenv $$
              text "cenv" <+> ppr cenv $$