Commit f7df28a4 authored by simonpj@microsoft.com's avatar simonpj@microsoft.com
Browse files

Wibbles to field-label puns

parent 0a594fab
......@@ -177,13 +177,21 @@ data HsRecFields id arg -- A bunch of record fields
-- { x = 3, y = True }
-- Used for both expressions and patterns
= HsRecFields { rec_flds :: [HsRecField id arg],
rec_dotdot :: Maybe Int }
-- Nothing => the normal case
-- Just n => the group uses ".." notation,
-- and the first n elts of rec_flds
-- were the user-written ones
-- (In the latter case, the remaining elts of
-- rec_flds are the non-user-written ones)
rec_dotdot :: Maybe Int } -- Note [DotDot fields]
-- Note [DotDot fields]
-- ~~~~~~~~~~~~~~~~~~~~
-- The rec_dotdot field means this:
-- Nothing => the normal case
-- Just n => the group uses ".." notation,
--
-- In the latter case:
--
-- *before* renamer: rec_flds are exactly the n user-written fields
--
-- *after* renamer: rec_flds includes *all* fields, with
-- the first 'n' being the user-written ones
-- and the remainder being 'filled in' implicitly
data HsRecField id arg = HsRecField {
hsRecFieldId :: Located id,
......@@ -196,9 +204,12 @@ data HsRecField id arg = HsRecField {
-- If you write T { x, y = v+1 }, the HsRecFields will be
-- HsRecField x x True ...
-- HsRecField y (v+1) False ...
-- That is, for "punned" field x is immediately expanded to x=x
-- but with a punning flag so we can detect it later
-- That is, for "punned" field x is expanded (in the renamer)
-- to x=x; but with a punning flag so we can detect it later
-- (e.g. when pretty printing)
--
-- If the original field was qualified, we un-qualify it, thus
-- T { A.x } means T { A.x = x }
hsRecFields :: HsRecFields id arg -> [id]
hsRecFields rbinds = map (unLoc . hsRecFieldId) (rec_flds rbinds)
......
......@@ -1639,7 +1639,7 @@ fbinds1 :: { ([HsRecField RdrName (LHsExpr RdrName)], Bool) }
fbind :: { HsRecField RdrName (LHsExpr RdrName) }
: qvar '=' exp { HsRecField $1 $3 False }
| qvar { HsRecField $1 (L (getLoc $1) (HsVar (unLoc $1))) True }
| qvar { HsRecField $1 (L (getLoc $1) placeHolderPunRhs) True }
-- Here's where we say that plain 'x'
-- means exactly 'x = x'. The pun-flag boolean is
-- there so we can still print it right
......
......@@ -19,6 +19,7 @@ module RdrHsSyn (
cvBindsAndSigs,
cvTopDecls,
findSplice, checkDecBrGroup,
placeHolderPunRhs,
-- Stuff to do with Foreign declarations
mkImport,
......@@ -789,9 +790,15 @@ checkAPat dynflags loc e = case e of
HsType ty -> return (TypePat ty)
_ -> patFail loc
plus_RDR, bang_RDR :: RdrName
placeHolderPunRhs :: HsExpr RdrName
-- The RHS of a punned record field will be filled in by the renamer
-- It's better not to make it an error, in case we want to print it when debugging
placeHolderPunRhs = HsVar pun_RDR
plus_RDR, bang_RDR, pun_RDR :: RdrName
plus_RDR = mkUnqual varName (fsLit "+") -- Hack
bang_RDR = mkUnqual varName (fsLit "!") -- Hack
pun_RDR = mkUnqual varName (fsLit "pun-right-hand-side")
checkPatField :: HsRecField RdrName (LHsExpr RdrName) -> P (HsRecField RdrName (LPat RdrName))
checkPatField fld = do { p <- checkLPat (hsRecFieldArg fld)
......
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