diff options
| -rw-r--r-- | compiler/parser/Parser.y | 65 | ||||
| -rw-r--r-- | compiler/parser/RdrHsSyn.hs | 20 | ||||
| -rw-r--r-- | testsuite/tests/gadt/records-fail1.hs | 12 | ||||
| -rw-r--r-- | testsuite/tests/gadt/records-fail1.stderr | 7 |
4 files changed, 38 insertions, 66 deletions
diff --git a/compiler/parser/Parser.y b/compiler/parser/Parser.y index 1cfe491461..4b8eca6b5a 100644 --- a/compiler/parser/Parser.y +++ b/compiler/parser/Parser.y @@ -82,10 +82,9 @@ import Util ( looksLikePackageName ) } -{- Last updated: 29 Jul 2015 +{- Last updated: 31 Jul 2015 Conflicts: 47 shift/reduce - 2 reduce/reduce If you modify this parser and add a conflict, please update this comment. You can learn more about the conflicts by passing 'happy' the -i flag: @@ -293,29 +292,6 @@ state 950 contains 1 shift/reduce conflicts. Conflict: 'by' -------------------------------------------------------------------------------- - -state 1230 contains 1 reduce/reduce conflicts. - - *** tyconsym -> ':' . (rule 653) - consym -> ':' . (rule 721) - - Conflict: ')' - -------------------------------------------------------------------------------- - -state 1231 contains 1 reduce/reduce conflicts. - - *** tyconsym -> CONSYM . (rule 651) - consym -> CONSYM . (rule 720) - - Conflict: ')' - -TODO: Why? (NB: This one has been around for a while; it's quite puzzling - because we really shouldn't get confused between tyconsym and consym. - Trace the state machine, maybe?) - -TODO: Same as State 1230 ------------------------------------------------------------------------------- -- API Annotations @@ -1820,18 +1796,24 @@ gadt_constr_with_doc {% return $1 } gadt_constr :: { LConDecl RdrName } - -- Returns a list because of: C,D :: ty + -- see Note [Difference in parsing GADT and data constructors] + -- Returns a list because of: C,D :: ty : con_list '::' sigtype {% do { (anns,gadtDecl) <- mkGadtDecl (unLoc $1) $3 ; ams (sLL $1 $> gadtDecl) (mj AnnDcolon $2:anns) } } - -- Deprecated syntax for GADT record declarations - | oqtycon '{' fielddecls '}' '::' sigtype - {% do { cd <- mkDeprecatedGadtRecordDecl (comb2 $1 $6) $1 (noLoc $3) $6 - ; cd' <- checkRecordSyntax cd - ; ams (L (comb2 $1 $6) (unLoc cd')) - [moc $2,mcc $4,mj AnnDcolon $5] } } +{- Note [Difference in parsing GADT and data constructors] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +GADT constructors have simpler syntax than usual data constructors: +in GADTs, types cannot occur to the left of '::', so they cannot be mixed +with constructor names (see Note [Parsing data constructors is hard]). + +Due to simplified syntax, GADT constructor names (left-hand side of '::') +use simpler grammar production than usual data constructor names. As a +consequence, GADT constructor names are resticted (names like '(*)' are +allowed in usual data constructors, but not in GADTs). +-} constrs :: { Located ([AddAnn],[LConDecl RdrName]) } : maybe_docnext '=' constrs1 { L (comb2 $2 $3) ([mj AnnEqual $2] @@ -1862,16 +1844,21 @@ forall :: { Located ([AddAnn],[LHsTyVarBndr RdrName]) } | {- empty -} { noLoc ([],[]) } constr_stuff :: { Located (Located RdrName, HsConDeclDetails RdrName) } --- We parse the constructor declaration --- C t1 t2 --- as a btype (treating C as a type constructor) and then convert C to be --- a data constructor. Reason: it might continue like this: --- C t1 t2 %: D Int --- in which case C really would be a type constructor. We can't resolve this --- ambiguity till we come across the constructor oprerator :% (or not, more usually) + -- see Note [Parsing data constructors is hard] : btype {% splitCon $1 >>= return.sLL $1 $> } | btype conop btype { sLL $1 $> ($2, InfixCon $1 $3) } +{- Note [Parsing data constructors is hard] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +We parse the constructor declaration + C t1 t2 +as a btype (treating C as a type constructor) and then convert C to be +a data constructor. Reason: it might continue like this: + C t1 t2 %: D Int +in which case C really would be a type constructor. We can't resolve this +ambiguity till we come across the constructor oprerator :% (or not, more usually) +-} + fielddecls :: { [LConDeclField RdrName] } : {- empty -} { [] } | fielddecls1 { $1 } diff --git a/compiler/parser/RdrHsSyn.hs b/compiler/parser/RdrHsSyn.hs index ab3f17d182..18890b594f 100644 --- a/compiler/parser/RdrHsSyn.hs +++ b/compiler/parser/RdrHsSyn.hs @@ -35,7 +35,6 @@ module RdrHsSyn ( mkExtName, -- RdrName -> CLabelString mkGadtDecl, -- [Located RdrName] -> LHsType RdrName -> ConDecl RdrName mkSimpleConDecl, - mkDeprecatedGadtRecordDecl, mkATDefault, -- Bunch of functions in the parser monad for @@ -469,25 +468,6 @@ mkPatSynMatchGroup (L _ patsyn_name) (L _ decls) = text "pattern synonym 'where' clause must bind the pattern synonym's name" <+> quotes (ppr patsyn_name) $$ ppr decl -mkDeprecatedGadtRecordDecl :: SrcSpan - -> Located RdrName - -> Located [LConDeclField RdrName] - -> LHsType RdrName - -> P (LConDecl RdrName) --- This one uses the deprecated syntax --- C { x,y ::Int } :: T a b --- We give it a RecCon details right away -mkDeprecatedGadtRecordDecl loc (L con_loc con) flds res_ty - = do { data_con <- tyConToDataCon con_loc con - ; return (L loc (ConDecl { con_old_rec = True - , con_names = [data_con] - , con_explicit = Implicit - , con_qvars = mkHsQTvs [] - , con_cxt = noLoc [] - , con_details = RecCon flds - , con_res = ResTyGADT loc res_ty - , con_doc = Nothing })) } - mkSimpleConDecl :: Located RdrName -> [LHsTyVarBndr RdrName] -> LHsContext RdrName -> HsConDeclDetails RdrName -> ConDecl RdrName diff --git a/testsuite/tests/gadt/records-fail1.hs b/testsuite/tests/gadt/records-fail1.hs index 8eefee51e7..b26404afd3 100644 --- a/testsuite/tests/gadt/records-fail1.hs +++ b/testsuite/tests/gadt/records-fail1.hs @@ -2,10 +2,18 @@ -- Tests record syntax for GADTs +-- Record syntax in GADTs has been deprecated since July 2009 +-- see commit 432b9c9322181a3644083e3c19b7e240d90659e7 by simonpj: +-- "New syntax for GADT-style record declarations, and associated refactoring" +-- and Trac #3306 + +-- It's been removed in August 2015 +-- see Phab D1118 + +-- test should result into parse error + module ShouldFail where data T a where T1 { x :: a, y :: b } :: T (a,b) T4 { x :: Int } :: T [a] - -
\ No newline at end of file diff --git a/testsuite/tests/gadt/records-fail1.stderr b/testsuite/tests/gadt/records-fail1.stderr index 6fd871cbf7..9e8c80bb3b 100644 --- a/testsuite/tests/gadt/records-fail1.stderr +++ b/testsuite/tests/gadt/records-fail1.stderr @@ -1,5 +1,2 @@ -
-records-fail1.hs:7:1: error:
- Constructors T1 and T4 have a common field ‘x’,
- but have different result types
- In the data type declaration for ‘T’
+ +records-fail1.hs:18:6: error: parse error on input ‘{’ |