Allow toplevel definitions in syntax and parsing

Author: odersky

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

@@ -1994,7 +1994,7 @@ object Parsers {
     /** ClsParamClauses   ::=  {ClsParamClause} [[nl] `(' [FunArgMods] ClsParams `)']
      *  ClsParamClause    ::=  [nl] `(' [`erased'] [ClsParams] ')'
      *  ClsParams         ::=  ClsParam {`' ClsParam}
-     *  ClsParam          ::=  {Annotation} [{Modifier} (`val' | `var') | `inline'] Param
+     *  ClsParam          ::=  {Annotation} [{ParamModifier} (`val' | `var') | `inline'] Param
      *  DefParamClauses   ::=  {DefParamClause} [[nl] `(' [FunArgMods] DefParams `)']
      *  DefParamClause    ::=  [nl] `(' [`erased'] [DefParams] ')'
      *  DefParams         ::=  DefParam {`,' DefParam}
@@ -2594,7 +2594,7 @@ object Parsers {
     }
 
     /** TopStatSeq ::= TopStat {semi TopStat}
-     *  TopStat ::= Annotations Modifiers TmplDef
+     *  TopStat ::= Annotations Modifiers Def
      *            | Packaging
      *            | package object objectDef
      *            | Import
@@ -2614,15 +2614,13 @@ object Parsers {
         }
         else if (in.token == IMPORT)
           stats ++= importClause()
-        else if (in.token == AT || isTemplateIntro || isModifier)
-          stats +++= tmplDef(in.offset, defAnnotsMods(modifierTokens))
+        else if (in.token == AT || isDefIntro(modifierTokens))
+          stats +++= defOrDcl(in.offset, defAnnotsMods(modifierTokens))
         else if (!isStatSep) {
           if (in.token == CASE)
             syntaxErrorOrIncomplete(OnlyCaseClassOrCaseObjectAllowed())
           else
             syntaxErrorOrIncomplete(ExpectedClassOrObjectDef())
-          if (mustStartStat) // do parse all definitions even if they are probably local (i.e. a "}" has been forgotten)
-            defOrDcl(in.offset, defAnnotsMods(modifierTokens))
         }
         acceptStatSepUnlessAtEnd()
       }

docs/docs/internals/syntax.md

@@ -390,10 +390,11 @@ EnumStat          ::=  TemplateStat
 EnumCase          ::=  ‘case’ (id ClassConstr [‘extends’ ConstrApps]] | ids)
 
 TopStatSeq        ::=  TopStat {semi TopStat}
-TopStat           ::=  {Annotation [nl]} {Modifier} TmplDef
-                    |  Import
+TopStat           ::=  Import
+                    |  {Annotation [nl]} {Modifier} Def
                     |  Packaging
                     |  PackageObject
+                    |
 Packaging         ::=  ‘package’ QualId [nl] ‘{’ TopStatSeq ‘}’                 Package(qid, stats)
 PackageObject     ::=  ‘package’ ‘object’ ObjectDef                             object with package in mods.