support for single-expr implicit dimensions

src/Language/SystemVerilog/Parser/Parse.y

@@ -355,8 +355,11 @@ Dimensions :: { [Range] }
   : {- empty -}        { [] }
   | DimensionsNonEmpty { $1 }
 DimensionsNonEmpty :: { [Range] }
-  : Range                    { [$1] }
-  | DimensionsNonEmpty Range { $1 ++ [$2] }
+  : Dimension                    { [$1] }
+  | DimensionsNonEmpty Dimension { $1 ++ [$2] }
+Dimension :: { Range }
+  : Range        { $1 }
+  | "[" Expr "]" { (simplify $  BinOp Sub $2 (Number "1"), Number "0") }
 
 DeclAsgns :: { [(Identifier, Expr)] }
   : DeclAsgn               { [$1] }

src/Language/SystemVerilog/Parser/ParseDecl.hs

@@ -239,9 +239,15 @@ takeType (DTIdent tn : rest) = (Alias tn, rest)
 takeType               rest  = (Implicit, rest)
 
 takeRanges :: [DeclToken] -> ([Range], [DeclToken])
-takeRanges (DTRange r : rest) = (r : rs, rest')
-    where (rs, rest') = takeRanges rest
-takeRanges rest = ([], rest)
+takeRanges [] = ([], [])
+takeRanges (token : tokens) =
+    case token of
+        DTRange r -> (r         : rs, rest          )
+        DTBit   s -> (asRange s : rs, rest          )
+        _         -> ([]            , token : tokens)
+    where
+        (rs, rest) = takeRanges tokens
+        asRange s = (simplify $ BinOp Sub s (Number "1"), Number "0")
 
 -- TODO: entrypoints besides `parseDTsAsDeclOrAsgn` should disallow `DTAsgnNBlk`
 -- Note: matching DTAsgnNBlk too is a bit of a hack to allow for tripLookahead