Remove the Unicode alternative for ".." (#3894)

[ghc-hetmet.git] / compiler / parser / Lexer.x

diff --git a/compiler/parser/Lexer.x b/compiler/parser/Lexer.x
index 3a001bd..2493b21 100644 (file)
--- a/compiler/parser/Lexer.x
+++ b/compiler/parser/Lexer.x
@@ -701,7 +701,6 @@ reservedSymsFM = listToUFM $
                                 explicitForallEnabled i)
        ,("→",   ITrarrow, unicodeSyntaxEnabled)
        ,("←",   ITlarrow, unicodeSyntaxEnabled)
-       ,("⋯",   ITdotdot, unicodeSyntaxEnabled)
 
        ,("⤙",   ITlarrowtail, \i -> unicodeSyntaxEnabled i && arrowsEnabled i)
        ,("⤚",   ITrarrowtail, \i -> unicodeSyntaxEnabled i && arrowsEnabled i)
@@ -1981,7 +1980,9 @@ alternativeLayoutRuleToken t
          mExpectingOCurly <- getAlrExpectingOCurly
          justClosedExplicitLetBlock <- getJustClosedExplicitLetBlock
          setJustClosedExplicitLetBlock False
-         let thisLoc = getLoc t
+         dflags <- getDynFlags
+         let transitional = dopt Opt_AlternativeLayoutRuleTransitional dflags
+             thisLoc = getLoc t
              thisCol = srcSpanStartCol thisLoc
              newLine = (lastLoc == noSrcSpan)
                     || (srcSpanStartLine thisLoc > srcSpanEndLine lastLoc)
@@ -2040,6 +2041,30 @@ alternativeLayoutRuleToken t
                  do setPendingImplicitTokens [t]
                     setALRContext ls
                     return (L thisLoc ITccurly)
+             -- This next case is to handle a transitional issue:
+             (ITwhere, ALRLayout _ col : ls, _)
+              | newLine && thisCol == col && transitional ->
+                 do addWarning Opt_WarnAlternativeLayoutRuleTransitional
+                               thisLoc
+                               (transitionalAlternativeLayoutWarning
+                                    "`where' clause at the same depth as implicit layout block")
+                    setALRContext ls
+                    setNextToken t
+                    -- Note that we use lastLoc, as we may need to close
+                    -- more layouts, or give a semicolon
+                    return (L lastLoc ITccurly)
+             -- This next case is to handle a transitional issue:
+             (ITvbar, ALRLayout _ col : ls, _)
+              | newLine && thisCol == col && transitional ->
+                 do addWarning Opt_WarnAlternativeLayoutRuleTransitional
+                               thisLoc
+                               (transitionalAlternativeLayoutWarning
+                                    "`|' at the same depth as implicit layout block")
+                    setALRContext ls
+                    setNextToken t
+                    -- Note that we use lastLoc, as we may need to close
+                    -- more layouts, or give a semicolon
+                    return (L lastLoc ITccurly)
              (_, ALRLayout _ col : ls, _)
               | newLine && thisCol == col ->
                  do setNextToken t
@@ -2050,10 +2075,8 @@ alternativeLayoutRuleToken t
                     -- Note that we use lastLoc, as we may need to close
                     -- more layouts, or give a semicolon
                     return (L lastLoc ITccurly)
-             (u, _, _)
-              | isALRopen u ->
-                 do setALRContext (ALRNoLayout (containsCommas u) False : context)
-                    return t
+             -- We need to handle close before open, as 'then' is both
+             -- an open and a close
              (u, _, _)
               | isALRclose u ->
                  case context of
@@ -2062,13 +2085,24 @@ alternativeLayoutRuleToken t
                         setNextToken t
                         return (L thisLoc ITccurly)
                  ALRNoLayout _ isLet : ls ->
-                     do setALRContext ls
+                     do let ls' = if isALRopen u
+                                     then ALRNoLayout (containsCommas u) False : ls
+                                     else ls
+                        setALRContext ls'
                         when isLet $ setJustClosedExplicitLetBlock True
                         return t
                  [] ->
-                     -- XXX This is an error in John's code, but
-                     -- it looks reachable to me at first glance
-                     return t
+                     do let ls = if isALRopen u
+                                    then [ALRNoLayout (containsCommas u) False]
+                                    else ls
+                        setALRContext ls
+                        -- XXX This is an error in John's code, but
+                        -- it looks reachable to me at first glance
+                        return t
+             (u, _, _)
+              | isALRopen u ->
+                 do setALRContext (ALRNoLayout (containsCommas u) False : context)
+                    return t
              (ITin, ALRLayout ALRLayoutLet _ : ls, _) ->
                  do setALRContext ls
                     setPendingImplicitTokens [t]
@@ -2090,9 +2124,15 @@ alternativeLayoutRuleToken t
              -- the other ITwhere case omitted; general case below covers it
              (_, _, _) -> return t
 
+transitionalAlternativeLayoutWarning :: String -> SDoc
+transitionalAlternativeLayoutWarning msg
+    = text "transitional layout will not be accepted in the future:"
+   $$ text msg
+
 isALRopen :: Token -> Bool
 isALRopen ITcase        = True
 isALRopen ITif          = True
+isALRopen ITthen        = True
 isALRopen IToparen      = True
 isALRopen ITobrack      = True
 isALRopen ITocurly      = True
@@ -2104,6 +2144,7 @@ isALRopen _             = False
 isALRclose :: Token -> Bool
 isALRclose ITof     = True
 isALRclose ITthen   = True
+isALRclose ITelse   = True
 isALRclose ITcparen = True
 isALRclose ITcbrack = True
 isALRclose ITccurly = True