Don't require colon after class or object sigs

# Conflicts:
#	compiler/src/dotty/tools/backend/jvm/GenBCode.scala

Author: odersky

compiler/src/dotty/tools/backend/jvm/GenBCode.scala

@@ -1178,6 +1178,11 @@ object Parsers {
       newLineOptWhenFollowedBy(LBRACE)
     }
 
+    def possibleTemplateStart(): Unit = {
+      in.observeIndented()
+      newLineOptWhenFollowedBy(LBRACE)
+    }
+
     def indentRegion[T](tag: EndMarkerTag)(op: => T): T = {
       val iw = in.currentRegion.indentWidth
       val t = op
@@ -3330,7 +3335,7 @@ object Parsers {
           if (in.token == LPAREN)
             try paramClause(prefix = true) :: Nil
             finally {
-              possibleBracesStart()
+              possibleTemplateStart()
               if (!in.isNestedStart) syntaxErrorOrIncomplete("`{' expected")
             }
           else Nil
@@ -3348,7 +3353,7 @@ object Parsers {
             DefDef(name, tparams, vparamss, parents.head, expr())
           }
           else {
-            possibleBracesStart()
+            possibleTemplateStart()
             val (tparams1, vparamss1) =
               if (leadingParamss.nonEmpty)
                 (tparams, leadingParamss)
@@ -3448,7 +3453,7 @@ object Parsers {
      */
     def template(constr: DefDef, isEnum: Boolean = false): Template = {
       val (parents, derived) = inheritClauses()
-      possibleBracesStart()
+      possibleTemplateStart()
       if (isEnum) {
         val (self, stats) = withinEnum(templateBody())
         Template(constr, parents, derived, self, stats)
@@ -3458,13 +3463,15 @@ object Parsers {
 
     /** TemplateOpt = [Template]
      */
-    def templateOpt(constr: DefDef): Template = {
+    def templateOpt(constr: DefDef): Template =
       possibleBracesStart()
-      if (in.token == EXTENDS || isIdent(nme.derives) || in.isNestedStart)
+      if (in.token == EXTENDS || isIdent(nme.derives))
         template(constr)
-      else
-        Template(constr, Nil, Nil, EmptyValDef, Nil)
-    }
+      else {
+        possibleTemplateStart()
+        if (in.isNestedStart) template(constr)
+        else Template(constr, Nil, Nil, EmptyValDef, Nil)
+      }
 
     /** TemplateBody ::= [nl] `{' TemplateStatSeq `}'
      */
@@ -3496,7 +3503,7 @@ object Parsers {
     def packaging(start: Int): Tree = {
       val pkg = qualId()
       indentRegion(pkg) {
-        possibleBracesStart()
+        possibleTemplateStart()
         val stats = inDefScopeBraces(topStatSeq())
         makePackaging(start, pkg, stats)
       }
@@ -3702,7 +3709,7 @@ object Parsers {
           else {
             val pkg = qualId()
             indentRegion(pkg) {
-              possibleBracesStart()
+              possibleTemplateStart()
               if (in.token == EOF)
                 ts += makePackaging(start, pkg, List())
               else if (in.isNestedStart) {

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -372,7 +372,7 @@ object Scanners {
     def isLeadingInfixOperator() = (
           allowLeadingInfixOperators
       && (  token == BACKQUOTED_IDENT
-          || token == IDENTIFIER && isOperatorPart(name(name.length - 1)))
+         || token == IDENTIFIER && isOperatorPart(name(name.length - 1)))
       && ch == ' '
       && !pastBlankLine
       && {
@@ -531,6 +531,25 @@ object Scanners {
       }
     }
 
+    def observeIndented(): Unit =
+      if (indentSyntax && isAfterLineEnd && token != INDENT) {
+        val newLineInserted = token == NEWLINE || token == NEWLINES
+        val nextOffset = if (newLineInserted) next.offset else offset
+        val nextWidth = indentWidth(nextOffset)
+        val lastWidth = currentRegion match {
+          case r: Indented => r.width
+          case r: InBraces => r.width
+          case _ => nextWidth
+        }
+
+        if (lastWidth < nextWidth) {
+          currentRegion = Indented(nextWidth, Set(), COLONEOL, currentRegion)
+          if (!newLineInserted) next.copyFrom(this)
+          offset = nextOffset
+          token = INDENT
+        }
+      }
+
     /** - Join CASE + CLASS => CASECLASS, CASE + OBJECT => CASEOBJECT, SEMI + ELSE => ELSE, COLON + <EOL> => COLONEOL
      *  - Insert missing OUTDENTs at EOF
      */
@@ -1342,6 +1361,7 @@ object Scanners {
       }
     }
   }
+
   object IndentWidth {
     private inline val MaxCached = 40
     private val spaces = Array.tabulate(MaxCached + 1)(new Run(' ', _))

compiler/src/dotty/tools/dotc/parsing/Scanners.scala

@@ -1,4 +1,4 @@
-object Test:
+object Test
 
   locally:
     var x = 0
@@ -52,28 +52,28 @@ object Test:
     x < 10
   do ()
 
-class Test2:
+class Test2
   self =>
   def foo = 1
 
-  object x:
+  object x
     new Test2:
       override def foo = 2
       end new               // error: end of statement expected but new found  // error: not found: end
     def bar = 2             // error: ';' expected, but unindent found
   end Test2                 // error: misaligned end marker
 end Test2
 
-class Test3:
+class Test3
  self =>
   def foo = 1
  end Test3  // error: not found: end
 
 import collection.mutable.HashMap
 
-class Coder(words: List[String]):
+class Coder(words: List[String])
 
-  class Foo:
+  class Foo
     println()
     end Foo  // error: not found: end
 

tests/neg/endmarkers.scala

@@ -1,4 +1,4 @@
-object Test:
+object Test
 
 	if true then
 		println(1)   // ok
@@ -7,7 +7,7 @@ object Test:
 	  println(4)   // error
  else ()         // error // error
 
-	object Test2:
+	object Test2
 
 	    if true then
 	      1

tests/neg/spaces-vs-tabs.scala

@@ -1,4 +1,4 @@
-object Test:
+object Test
 
   locally:
     var x = 0
@@ -56,7 +56,7 @@ object Test:
     x < 10
   do ()
 
-class Test2:
+class Test2
   self =>
   def foo = 1
 
@@ -67,15 +67,15 @@ class Test2:
   end x
 end Test2
 
-class Test3:
+class Test3
  self =>
   def foo = 1
 
 import collection.mutable.HashMap
 
-class Coder(words: List[String]):
+class Coder(words: List[String])
 
-  class Foo:
+  class Foo
     println()
   end Foo
 

tests/pos/indent.scala

@@ -1,7 +1,12 @@
-object testindent:
-  if 1 > 0 then
+object testindent
+
+  class C
+    val x = 0
+
+  val c = new C
+  if 1 > c.x then
     println
     println
   else
     println
-    println
+    println

tests/pos/indent2.scala

@@ -5,8 +5,8 @@ trait Parsers {
   type Input = List[Char]
 
   sealed class ParseResult[+t](val next: Input)
-    case class Success[+t](override val next: Input, result: t) extends ParseResult[t](next)
-    case class Failure(override val next: Input, msg: String) extends ParseResult[Nothing](next)
+  case class Success[+t](override val next: Input, result: t) extends ParseResult[t](next)
+  case class Failure(override val next: Input, msg: String) extends ParseResult[Nothing](next)
 
   abstract class Parser[+t] {
     def apply(in: Input): ParseResult[t]