[Git][ghc/ghc][wip/ani/T27156] add ReSynBindsE, ReSynBindsRn and ReSynBindsTc

2 Nov 2026


      Apoorv Ingle pushed to branch wip/ani/T27156 at Glasgow Haskell Compiler / GHC


Commits:
c08de6dd by Apoorv Ingle at 2026-11-01T22:53:44-06:00
add ReSynBindsE, ReSynBindsRn and ReSynBindsTc

- - - - -


15 changed files:

- compiler/GHC/Builtin/TH.hs
- compiler/GHC/Hs/Expr.hs
- compiler/GHC/Hs/Syn/Type.hs
- compiler/GHC/HsToCore/Expr.hs
- compiler/GHC/HsToCore/Quote.hs
- compiler/GHC/HsToCore/Ticks.hs
- compiler/GHC/Iface/Ext/Ast.hs
- compiler/GHC/Rename/Expr.hs
- compiler/GHC/Tc/Gen/Expand.hs
- compiler/GHC/Tc/Gen/Expr.hs
- compiler/GHC/Tc/Gen/Splice.hs
- compiler/GHC/Tc/Types/Origin.hs
- compiler/GHC/Tc/Zonk/Type.hs
- compiler/GHC/ThToHs.hs
- libraries/ghc-internal/src/GHC/Internal/TH/Lib.hs


Changes:

=====================================
compiler/GHC/Builtin/TH.hs
=====================================
@@ -108,7 +108,7 @@ varEOcc, conEOcc, litEOcc, appEOcc, appTypeEOcc, infixAppOcc, sectionLOcc,
   unboxedSumEOcc, condEOcc, multiIfEOcc, letEOcc, caseEOcc, doEOcc, mdoEOcc,
   compEOcc, staticEOcc, unboundVarEOcc, labelEOcc, implicitParamVarEOcc,
   getFieldEOcc, projectionEOcc, typeEOcc, forallEOcc, forallVisEOcc,
-  constrainedEOcc :: KnownOcc
+  constrainedEOcc, resynbindEOcc :: KnownOcc
 varEOcc              = mkVarOcc "varE"
 conEOcc              = mkVarOcc "conE"
 litEOcc              = mkVarOcc "litE"
@@ -152,6 +152,7 @@ typeEOcc             = mkVarOcc "typeE"
 forallEOcc           = mkVarOcc "forallE"
 forallVisEOcc        = mkVarOcc "forallVisE"
 constrainedEOcc      = mkVarOcc "constrainedE"
+resynbindEOcc        = mkVarOcc "reSynBindsE"
 
 -- type FieldExp = ...
 fieldExpOcc :: KnownOcc


=====================================
compiler/GHC/Hs/Expr.hs
=====================================
@@ -666,7 +666,7 @@ type instance XXExpr GhcTc = XXExprGhcTc
 ********************************************************************* -}
 
 data XXExprGhcPs
-  = ReSynBinds HsModuleName (HsExpr GhcPs)
+  = ReSynBindsPs HsModuleName (HsExpr GhcPs)
 
 
 -- See Note [Rebindable syntax and XXExprGhcRn]
@@ -684,6 +684,7 @@ data XXExprGhcRn
   | HsRecSelRn  (FieldOcc GhcRn)   -- ^ Variable pointing to record selector
                            -- See Note [Non-overloaded record field selectors] and
                            -- Note [Record selectors in the AST]
+  | ReSynBindsRn HsModuleName (HsExpr GhcRn)
 
 
 data XXExprGhcTc
@@ -714,6 +715,7 @@ data XXExprGhcTc
   | HsRecSelTc  (FieldOcc GhcTc) -- ^ Variable pointing to record selector
                              -- See Note [Non-overloaded record field selectors] and
                              -- Note [Record selectors in the AST]
+  | ReSynBindsTc HsModuleName (HsExpr GhcTc)
 
 {- *********************************************************************
 *                                                                      *
@@ -1039,7 +1041,7 @@ ppr_expr (XExpr x) = case ghcPass @p of
   GhcTc -> ppr x
 
 instance Outputable XXExprGhcPs where
-  ppr (ReSynBinds m e) = text "{{" <+> ppr m <+> text "}}" <+> ppr e
+  ppr (ReSynBindsPs m e) = text "{{" <+> ppr m <+> text "}}" <+> ppr e
 
 ppr_hse :: forall p. (IsPass p) => HsExpansion (GhcPass p) -> SDoc
 ppr_hse hse
@@ -1061,6 +1063,7 @@ ppr_hse hse
 instance Outputable XXExprGhcRn where
   ppr (HsRecSelRn f)        = pprPrefixOcc f
   ppr (ExpandedThingRn hse) = ppr_hse hse
+  ppr (ReSynBindsRn m e)      = text "{{" <+> ppr m <+> text "}}" <+> ppr e
 
 
 instance Outputable XXExprGhcTc where
@@ -1088,6 +1091,8 @@ instance Outputable XXExprGhcTc where
             ppr exp, text ")"]
   ppr (HsRecSelTc f)      = pprPrefixOcc f
 
+  ppr (ReSynBindsTc m e)    = text "{{" <+> ppr m <+> text "}}" <+> ppr e
+
 ppr_infix_expr :: forall p. (OutputableBndrId p) => HsExpr (GhcPass p) -> Maybe SDoc
 ppr_infix_expr (HsVar _ (L _ v))    = Just (pprInfixOcc v)
 ppr_infix_expr (HsHole x) = Just $ pprInfixOcc $ case (ghcPass @p, x) of
@@ -1102,11 +1107,12 @@ ppr_infix_expr (XExpr x)            = case ghcPass @p of
 ppr_infix_expr _ = Nothing
 
 ppr_infix_expr_ps :: XXExprGhcPs -> Maybe SDoc
-ppr_infix_expr_ps (ReSynBinds{}) = Nothing
+ppr_infix_expr_ps (ReSynBindsPs{}) = Nothing
 
 ppr_infix_expr_rn :: XXExprGhcRn -> Maybe SDoc
 ppr_infix_expr_rn (ExpandedThingRn (HSE thing _)) = ppr_infix_hs_expansion thing
 ppr_infix_expr_rn (HsRecSelRn f)            = Just (pprInfixOcc f)
+ppr_infix_expr_rn (ReSynBindsRn _ e)          = ppr_infix_expr e
 
 ppr_infix_expr_tc :: XXExprGhcTc -> Maybe SDoc
 ppr_infix_expr_tc (WrapExpr _ e)    = ppr_infix_expr e
@@ -1115,6 +1121,7 @@ ppr_infix_expr_tc (ConLikeTc con)            = Just (pprInfixOcc (conLikeName co
 ppr_infix_expr_tc (HsTick {})                = Nothing
 ppr_infix_expr_tc (HsBinTick {})             = Nothing
 ppr_infix_expr_tc (HsRecSelTc f)            = Just (pprInfixOcc f)
+ppr_infix_expr_tc (ReSynBindsTc _ e)          = ppr_infix_expr e
 
 ppr_infix_hs_expansion :: HsCtxt -> Maybe SDoc
 ppr_infix_hs_expansion (ExprCtxt e) = ppr_infix_expr e
@@ -1199,7 +1206,7 @@ hsExprNeedsParens prec = go
                      GhcRn -> go_x_rn x
 
     go_x_ps :: XXExprGhcPs -> Bool
-    go_x_ps (ReSynBinds _ e) = hsExprNeedsParens prec e
+    go_x_ps (ReSynBindsPs _ e) = hsExprNeedsParens prec e
 
     go_x_tc :: XXExprGhcTc -> Bool
     go_x_tc (WrapExpr _ e)                   = hsExprNeedsParens prec e
@@ -1208,10 +1215,12 @@ hsExprNeedsParens prec = go
     go_x_tc (HsTick _ (L _ e))               = hsExprNeedsParens prec e
     go_x_tc (HsBinTick _ _ (L _ e))          = hsExprNeedsParens prec e
     go_x_tc (HsRecSelTc{})                   = False
+    go_x_tc (ReSynBindsTc _ e)               = hsExprNeedsParens prec e
 
     go_x_rn :: XXExprGhcRn -> Bool
     go_x_rn (ExpandedThingRn (HSE thing _))  = hsExpandedNeedsParens thing
     go_x_rn (HsRecSelRn{})               = False
+    go_x_rn (ReSynBindsRn _ e)               = hsExprNeedsParens prec e
 
     hsExpandedNeedsParens :: HsCtxt -> Bool
     hsExpandedNeedsParens (ExprCtxt e) = hsExprNeedsParens prec e
@@ -1260,10 +1269,12 @@ isAtomicHsExpr (XExpr x)
     go_x_tc (HsTick {})               = False
     go_x_tc (HsBinTick {})            = False
     go_x_tc (HsRecSelTc{})            = True
+    go_x_tc (ReSynBindsTc _ e)          = isAtomicHsExpr e
 
     go_x_rn :: XXExprGhcRn -> Bool
     go_x_rn (ExpandedThingRn (HSE thing _))   = isAtomicExpandedThingRn thing
     go_x_rn (HsRecSelRn{})              = True
+    go_x_rn (ReSynBindsRn _ e)            = isAtomicHsExpr e
 
     isAtomicExpandedThingRn :: HsCtxt -> Bool
     isAtomicExpandedThingRn (ExprCtxt e) = isAtomicHsExpr e
@@ -2388,7 +2399,7 @@ type instance XTypBr  GhcPs       = (EpToken "[t|", EpUniToken "|]" "⟧")
 type instance XVarBr  GhcPs       = EpaLocation
 type instance XXQuote GhcPs       = DataConCantHappen
 
-type instance XExpBr  GhcRn       = NoExtField
+type instance XExpBr  GhcRn       = NoExtField -- TODO ANI: What if we add the module name here?
 type instance XPatBr  GhcRn       = NoExtField
 type instance XDecBrL GhcRn       = NoExtField
 type instance XDecBrG GhcRn       = NoExtField


=====================================
compiler/GHC/Hs/Syn/Type.hs
=====================================
@@ -170,6 +170,7 @@ hsExprType (XExpr (ConLikeTc con)) = conLikeType con
 hsExprType (XExpr (HsTick _ e)) = lhsExprType e
 hsExprType (XExpr (HsBinTick _ _ e)) = lhsExprType e
 hsExprType (XExpr (HsRecSelTc (FieldOcc _ id))) = idType (unLoc id)
+hsExprType (XExpr (ReSynBindsTc _ e)) = hsExprType e
 
 arithSeqInfoType :: ArithSeqInfo GhcTc -> Type
 arithSeqInfoType asi = mkListTy $ case asi of


=====================================
compiler/GHC/HsToCore/Expr.hs
=====================================
@@ -310,6 +310,10 @@ dsExpr e@(XExpr ext_expr_tc)
       ConLikeTc {}  -> dsApp e
 
       ExpandedThingTc (HSE _ e) -> dsLExpr e
+      ReSynBindsTc m e ->
+        do
+        tracePm "dsExpr XExpr" (ppr m)
+        dsExpr e --TODO ANI: This should never happen?
 
       -- Hpc Support
       HsTick tickish e -> do
@@ -570,7 +574,9 @@ dsExpr (RecordCon { rcon_con  = L _ con_like
 -- Template Haskell stuff
 -- See Note [The life cycle of a TH quotation]
 
-dsExpr (HsTypedBracket   bracket_tc _) = dsBracket bracket_tc
+dsExpr (HsTypedBracket   bracket_tc _) = do
+  tracePm "dsExpr:dsBracket typed bracket" empty
+  dsBracket bracket_tc
 dsExpr (HsUntypedBracket bracket_tc _) = dsBracket bracket_tc
 dsExpr (HsTypedSplice   _   s) = pprPanic "dsExpr:typed splice" (pprTypedSplice Nothing s)
 dsExpr (HsUntypedSplice ext _) = dataConCantHappen ext


=====================================
compiler/GHC/HsToCore/Quote.hs
=====================================
@@ -1763,6 +1763,9 @@ repE e@(XExpr (ExpandedThingRn (HSE o x)))
   | otherwise
   = notHandled (ThExpressionForm e)
 repE (XExpr (HsRecSelRn (FieldOcc _ (L _ x)))) = repE (mkHsVar (noLocA x))
+repE (XExpr (ReSynBindsRn m e)) = do
+  e' <- repE e
+  repReSynBindsE m e'
 repE e@(HsPragE _ (HsPragSCC {}) _) = notHandled (ThCostCentres e)
 repE e@(HsTypedBracket{})   = notHandled (ThExpressionForm e)
 repE e@(HsUntypedBracket{}) = notHandled (ThExpressionForm e)
@@ -2613,6 +2616,16 @@ repDoE = repDoBlock doEOcc
 repMDoE :: Maybe HsModuleName -> Core [(M TH.Stmt)] -> MetaM (Core (M TH.Exp))
 repMDoE = repDoBlock mdoEOcc
 
+repReSynBindsE :: HsModuleName -> Core (M TH.Exp) -> MetaM (Core (M TH.Exp))
+repReSynBindsE m (MkC e) = do
+   MkC coreModName <- coreModNameM
+   krep2 resynbindEOcc [coreModName, e]
+  where
+    coreModNameM :: MetaM (Core TH.ModName)
+    coreModNameM = do
+      MkC s <- lift $ coreStringLit (moduleNameFS (hsModuleName m))
+      rep2_nw mkModNameOcc [s]
+
 repDoBlock :: KnownOcc -> Maybe HsModuleName -> Core [(M TH.Stmt)] -> MetaM (Core (M TH.Exp))
 repDoBlock doName maybeModName (MkC ss) = do
     MkC coreModName <- coreModNameM


=====================================
compiler/GHC/HsToCore/Ticks.hs
=====================================
@@ -708,6 +708,9 @@ addTickHsExpr (XExpr (HsBinTick t0 t1 e)) =
         liftM (XExpr . HsBinTick t0 t1) (addTickLHsExprNever e)
 
 addTickHsExpr e@(XExpr (HsRecSelTc (FieldOcc _ id)))   = do freeVar (unLoc id); return e
+addTickHsExpr (XExpr (ReSynBindsTc m e)) =
+        liftM (XExpr . ReSynBindsTc m) (addTickHsExpr e)
+
 
 addTickHsExpr (HsDo srcloc cxt (L l stmts))
   = do { (stmts', _) <- addTickLStmts' forQual stmts (return ())


=====================================
compiler/GHC/Iface/Ext/Ast.hs
=====================================
@@ -1377,6 +1377,8 @@ instance HiePass p => ToHie (LocatedA (HsExpr (GhcPass p))) where
           HsBinTick _ _ expr
             -> [ toHie expr
                ]
+          ReSynBindsTc _ _
+            -> []
           HsRecSelTc fld
             -> [ toHie $ RFC RecFieldOcc Nothing (L mspan fld)
                ]


=====================================
compiler/GHC/Rename/Expr.hs
=====================================
@@ -607,10 +607,10 @@ rnExpr (HsFunArr _ mult arg res)
       _ -> False
     oneType = noLocA $ HsVar noExtField $ noLocA $ noUserRdr oneDataConName
 
-rnExpr (XExpr (ReSynBinds m e'))
+rnExpr (XExpr (ReSynBindsPs m e))
   =  do { traceRn "XExpr ReSynBinds" (text "module:" <+> ppr m)
-        ; rnExpr e' -- for now just return the renamed expression
-          -- TODO: Bring into scope top level environment of the module m
+        ; (e', fvs) <- rnExpr e
+        ; return (e', fvs)
         }
 
 {-


=====================================
compiler/GHC/Tc/Gen/Expand.hs
=====================================
@@ -287,6 +287,7 @@ tcExpand e@(HsUntypedSplice splice_res _)
 
 ------------------------
 -- XExpr
+
 -- Expansions are idempotent, XExprs do not expand again
 tcExpand (XExpr (ExpandedThingRn hse))
   = return $ Just hse


=====================================
compiler/GHC/Tc/Gen/Expr.hs
=====================================
@@ -767,6 +767,11 @@ tcExprNoExpand (ArithSeq _ witness seq) res_ty
 tcExprNoExpand (HsTypedSplice ext splice)   res_ty = tcTypedSplice ext splice res_ty
 tcExprNoExpand e@(HsTypedBracket _ext body) res_ty = tcTypedBracket e body res_ty
 tcExprNoExpand e@(HsUntypedBracket ps body) res_ty = tcUntypedBracket e body ps res_ty
+tcExprNoExpand (XExpr (ReSynBindsRn m e))   res_ty
+  = do { traceTc "XExpr ReSynBinds" (text "module:" <+> ppr m)
+       ; e' <- tcExpr e res_ty
+       ; return $ XExpr (ReSynBindsTc m e')
+       }
 
 {-
 ************************************************************************


=====================================
compiler/GHC/Tc/Gen/Splice.hs
=====================================
@@ -713,7 +713,14 @@ tcTypedBracket rn_expr expr res_ty
        ; ps' <- readMutVar ps_var
        ; codeco <- tcLookupKnownOccId unsafeCodeCoerceOcc
        ; bracket_ty <- mkAppTy m_var <$> tcMetaKnownOccTy expTyConOcc
-       ; let brack_tc = HsBracketTc { hsb_quote = ExpBr noExtField expr, hsb_ty = bracket_ty
+       -- wrap the expression with ReSynBinds if rebindable syntax is on in this module
+       ; isRebindableSyntaxOn <- xoptM LangExt.RebindableSyntax
+       ; mname <- moduleName <$> getModule
+       ; let expr' = if isRebindableSyntaxOn
+                    then case expr of { L loc e -> L loc (XExpr $ ReSynBindsRn (toHsModuleName mname) e) }
+                    else expr
+       ; traceTc "tc_bracket rebindable wrap" (vcat [ppr isRebindableSyntaxOn, ppr mname])
+       ; let brack_tc = HsBracketTc { hsb_quote = ExpBr noExtField expr', hsb_ty = bracket_ty
                                     , hsb_wrap  = Just wrapper, hsb_splices = ps' }
              -- The tc_expr is stored here so that the expression can be used in HIE files.
              brack_expr = HsTypedBracket brack_tc tc_expr


=====================================
compiler/GHC/Tc/Types/Origin.hs
=====================================
@@ -639,6 +639,7 @@ exprCtOrigin (RecordUpd{})        = RecordUpdOrigin
 exprCtOrigin (HsGetField _ _ f)   = GetFieldOrigin (fmap (mkFastStringShortText . field_label) $ dfoLabel (unLoc f))
 exprCtOrigin (XExpr (ExpandedThingRn (HSE o _))) = hsCtxtCtOrigin o
 exprCtOrigin (XExpr (HsRecSelRn f))  = OccurrenceOfRecSel $ L (getLoc $ foLabel f) (foExt f)
+exprCtOrigin (XExpr (ReSynBindsRn _ e)) = exprCtOrigin e
 
 hsCtxtCtOrigin :: HsCtxt -> CtOrigin
 hsCtxtCtOrigin (ExprCtxt (ExprWithTySig _ (L _ e) _)) = exprCtOrigin e


=====================================
compiler/GHC/Tc/Zonk/Type.hs
=====================================
@@ -1096,6 +1096,10 @@ zonkExpr (XExpr (HsRecSelTc (FieldOcc occ (L l v))))
   = do { v' <- zonkIdOcc v
        ; return (XExpr (HsRecSelTc (FieldOcc occ (L l v')))) }
 
+zonkExpr (XExpr (ReSynBindsTc m e))
+  = do e' <- zonkExpr e
+       return $ (XExpr (ReSynBindsTc m e'))
+
 zonkExpr (RecordUpd x _ _)  = dataConCantHappen x
 zonkExpr (HsGetField x _ _) = dataConCantHappen x
 zonkExpr (HsProjection x _) = dataConCantHappen x


=====================================
compiler/GHC/ThToHs.hs
=====================================
@@ -1229,7 +1229,7 @@ cvtl e = wrapLA (cvt e)
                       mkHsForAllVisTele noAnn tvs'
          ; return $ HsForAll noExtField tele body' }
     cvt (ReSynBindsE m e) = do { e' <- cvt e
-                              ; return $ XExpr (ReSynBinds (mk_modtext m) e') }
+                              ; return $ XExpr (ReSynBindsPs (mk_modtext m) e') }
 
 {- | #16895 Ensure an infix expression's operator is a variable/constructor.
 Consider this example:


=====================================
libraries/ghc-internal/src/GHC/Internal/TH/Lib.hs
=====================================
@@ -438,6 +438,8 @@ forallVisE tvars body = ForallVisE <$> sequenceA tvars <*> body
 constrainedE :: Quote m => [m Exp] -> m Exp -> m Exp
 constrainedE ctx body = ConstrainedE <$> sequenceA ctx <*> body
 
+reSynBindsE :: Quote m => ModName -> m Exp -> m Exp
+reSynBindsE m e = ReSynBindsE m <$> e
 -------------------------------------------------------------------------------
 -- *   Dec
 



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[Git][ghc/ghc][wip/ani/T27156] add ReSynBindsE, ReSynBindsRn and ReSynBindsTc

Apoorv Ingle (＠ani)