lib: datep now requires years to be at least four digits.

hledger-lib/Hledger/Read/Common.hs

@@ -447,15 +447,15 @@ datep = do
 datep' :: Maybe Year -> TextParser m Day
 datep' mYear = do
     startOffset <- getOffset
-  d1 <- decimal <?> "year or month"
-  sep <- satisfy isDateSepChar <?> "date separator"
+    d1 <- yearorintp <?> "year or month"
+    sep <- datesepchar <?> "date separator"
     d2 <- decimal <?> "month or day"
-  fullDate startOffset d1 sep d2 <|> partialDate startOffset mYear d1 sep d2
+    case d1 of
+         Left y  -> fullDate startOffset y sep d2
+         Right m -> partialDate startOffset mYear m sep d2
     <?> "full or partial date"
-
   where
-
-  fullDate :: Int -> Integer -> Char -> Int -> TextParser m Day
+    fullDate :: Int -> Year -> Char -> Month -> TextParser m Day
     fullDate startOffset year sep1 month = do
       sep2 <- satisfy isDateSepChar <?> "date separator"
       day <- decimal <?> "day"
@@ -470,13 +470,12 @@ datep' mYear = do
                      "well-formed but invalid date: " ++ dateStr
         Just date -> pure $! date
 
-  partialDate
-    :: Int -> Maybe Year -> Integer -> Char -> Int -> TextParser m Day
+    partialDate :: Int -> Maybe Year -> Month -> Char -> MonthDay -> TextParser m Day
     partialDate startOffset mYear month sep day = do
       endOffset <- getOffset
       case mYear of
         Just year ->
-        case fromGregorianValid year (fromIntegral month) day of
+          case fromGregorianValid year month day of
             Nothing -> customFailure $ parseErrorAtRegion startOffset endOffset $
                         "well-formed but invalid date: " ++ dateStr
             Just date -> pure $! date
@@ -551,6 +550,14 @@ secondarydatep :: Day -> TextParser m Day
 secondarydatep primaryDate = char '=' *> datep' (Just primaryYear)
   where primaryYear = first3 $ toGregorian primaryDate
 
+-- | Parse a year number or an Int. Years must contain at least four
+-- digits.
+yearorintp :: TextParser m (Either Year Int)
+yearorintp = do
+    yearOrMonth <- takeWhile1P (Just "digit") isDigit
+    let n = readDecimal yearOrMonth
+    return $ if T.length yearOrMonth >= 4 then Left n else Right (fromInteger n)
+
 --- *** account names
 
 -- | Parse an account name (plus one following space if present),

tests/journal/posting-dates.test

@@ -50,5 +50,5 @@ end comment
 2000/1/2
    b  0   ; [1/1=1/2/3/4] bad second date, should error
 
->>>2 /9:23/
+>>>2 /-:9:21/
 >>>=1