Merge pull request #6290 from dotty-staging/fix-given-syntax

Disallow refinements in GivenTypes

Author: odersky

compiler/src/dotty/tools/dotc/ast/Desugar.scala

@@ -158,7 +158,7 @@ object desugar {
         vparamss = (setterParam :: Nil) :: Nil,
         tpt      = TypeTree(defn.UnitType),
         rhs      = setterRhs
-      ).withMods((mods | Accessor) &~ CaseAccessor)
+      ).withMods((mods | Accessor) &~ (CaseAccessor | Implicit | Given | Lazy))
       Thicket(vdef, setter)
     }
     else vdef

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

@@ -2082,12 +2082,12 @@ object Parsers {
       if (in.token == LBRACKET) typeParamClause(ownerKind) else Nil
 
     /** ClsParamClause    ::=  [nl] [‘erased’] ‘(’ [ClsParams] ‘)’
-     *                      |  ‘given’ [‘erased’] (‘(’ ClsParams ‘)’ | ContextTypes)
+     *                      |  ‘given’ [‘erased’] (‘(’ ClsParams ‘)’ | GivenTypes)
      *  ClsParams         ::=  ClsParam {`' ClsParam}
      *  ClsParam          ::=  {Annotation} [{ParamModifier} (`val' | `var') | `inline'] Param
      *  DefParamClause    ::=  [nl] [‘erased’] ‘(’ [DefParams] ‘)’ | GivenParamClause
-     *  GivenParamClause  ::=  ‘given’ [‘erased’] (‘(’ DefParams ‘)’ | ContextTypes)
-     *  ContextTypes      ::=  RefinedType {`,' RefinedType}
+     *  GivenParamClause  ::=  ‘given’ [‘erased’] (‘(’ DefParams ‘)’ | GivenTypes)
+     *  GivenTypes        ::=  RefinedType {`,' RefinedType}
      *  DefParams         ::=  DefParam {`,' DefParam}
      *  DefParam          ::=  {Annotation} [`inline'] Param
      *  Param             ::=  id `:' ParamType [`=' Expr]
@@ -2190,7 +2190,19 @@ object Parsers {
         }
         val isContextual = initialMods.is(Given)
         newLineOptWhenFollowedBy(LPAREN)
-        if (in.token == LPAREN) {
+        def isParamClause: Boolean =
+          !isContextual || {
+            val lookahead = in.lookaheadScanner
+            lookahead.nextToken()
+            paramIntroTokens.contains(lookahead.token) && {
+              lookahead.token != IDENTIFIER ||
+              lookahead.name == nme.inline || {
+                lookahead.nextToken()
+                lookahead.token == COLON
+              }
+            }
+          }
+        if (in.token == LPAREN && isParamClause) {
           if (ofInstance && !isContextual)
             syntaxError(em"parameters of instance definitions must come after `given'")
           val params = paramClause(
@@ -2203,7 +2215,7 @@ object Parsers {
           params :: (if (lastClause) Nil else recur(firstClause = false, nparams + params.length))
         }
         else if (isContextual) {
-          val tps = commaSeparated(refinedType)
+          val tps = commaSeparated(() => annotType())
           var counter = nparams
           def nextIdx = { counter += 1; counter }
           val params = tps.map(makeSyntheticParameter(nextIdx, _, Given | Implicit))
@@ -2612,8 +2624,8 @@ object Parsers {
 
     /** InstanceDef    ::=  [id] InstanceParams InstanceBody
      *  InstanceParams ::=  [DefTypeParamClause] {GivenParamClause}
-     *  InstanceBody   ::=  [‘of’ ConstrApp {‘,’ ConstrApp }] [TemplateBody]
-     *                   |  ‘of’ Type ‘=’ Expr
+     *  InstanceBody   ::=  [‘for’ ConstrApp {‘,’ ConstrApp }] [TemplateBody]
+     *                   |  ‘for’ Type ‘=’ Expr
      */
     def instanceDef(start: Offset, mods: Modifiers, instanceMod: Mod) = atSpan(start, nameStart) {
       var mods1 = addMod(mods, instanceMod)

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

@@ -240,6 +240,8 @@ object Tokens extends TokensCommon {
 
   final val modifierFollowers = modifierTokens | defIntroTokens
 
+  final val paramIntroTokens: TokenSet = modifierTokens | identifierTokens | BitSet(AT, VAL, VAR, IMPLICIT)
+
   /** Is token only legal as start of statement (eof also included)? */
   final val mustStartStatTokens: TokenSet = defIntroTokens | modifierTokens | BitSet(IMPORT, EXPORT, PACKAGE)
 

compiler/test/dotc/run-from-tasty.blacklist

@@ -3,3 +3,6 @@ eff-dependent.scala
 
 # It seems we still harmonize types in fromTasty. Not sure where this happens
 puzzle.scala
+
+# We get: class Foo needs to be abstract, since implicit val x$1: TC is not defined
+i2567.scala

docs/docs/internals/syntax.md

@@ -292,7 +292,7 @@ HkTypeParam       ::=  {Annotation} [‘+’ | ‘-’] (Id[HkTypeParamClause] |
 
 ClsParamClauses   ::=  {ClsParamClause} [[nl] ‘(’ [‘implicit’] ClsParams ‘)’]
 ClsParamClause    ::=  [nl] [‘erased’] ‘(’ [ClsParams] ‘)’
-                    |  ‘given’ [‘erased’] (‘(’ ClsParams ‘)’ | ContextTypes)
+                    |  ‘given’ [‘erased’] (‘(’ ClsParams ‘)’ | GivenTypes)
 ClsParams         ::=  ClsParam {‘,’ ClsParam}
 ClsParam          ::=  {Annotation}                                             ValDef(mods, id, tpe, expr) -- point of mods on val/var
                        [{Modifier} (‘val’ | ‘var’) | ‘inline’] Param
@@ -301,10 +301,10 @@ Param             ::=  id ‘:’ ParamType [‘=’ Expr]
 
 DefParamClauses   ::=  {DefParamClause} [[nl] ‘(’ [‘implicit’] DefParams ‘)’]
 DefParamClause    ::=  [nl] [‘erased’] ‘(’ [DefParams] ‘)’ | GivenParamClause
-GivenParamClause  ::=  ‘given’ [‘erased’] (‘(’ DefParams ‘)’ | ContextTypes)
+GivenParamClause  ::=  ‘given’ [‘erased’] (‘(’ DefParams ‘)’ | GivenTypes)
 DefParams         ::=  DefParam {‘,’ DefParam}
 DefParam          ::=  {Annotation} [‘inline’] Param                            ValDef(mods, id, tpe, expr) -- point of mods at id.
-ContextTypes      ::=  RefinedType {‘,’ RefinedType}
+GivenTypes        ::=  AnnotType {‘,’ AnnotType}
 ClosureMods       ::=  { ‘implicit’ | ‘erased’ | ‘given’}
 ```
 
@@ -356,7 +356,6 @@ Def               ::=  ‘val’ PatDef
                     |  ‘var’ VarDef
                     |  ‘def’ DefDef
                     |  ‘type’ {nl} TypeDcl
-                    |  ‘instance’ {nl} InstanceDef
                     |  TmplDef
                     |  INT
 PatDef            ::=  Pattern2 {‘,’ Pattern2} [‘:’ Type] ‘=’ Expr              PatDef(_, pats, tpe?, expr)
@@ -379,8 +378,8 @@ ObjectDef         ::=  id [Template]
 EnumDef           ::=  id ClassConstr InheritClauses EnumBody                   EnumDef(mods, name, tparams, template)
 InstanceDef       ::=  [id] InstanceParams InstanceBody
 InstanceParams    ::=  [DefTypeParamClause] {GivenParamClause}
-InstanceBody      ::=  [‘of’ ConstrApp {‘,’ ConstrApp }] [TemplateBody]
-                    |  ‘of’ Type ‘=’ Expr
+InstanceBody      ::=  [‘for’ ConstrApp {‘,’ ConstrApp }] [TemplateBody]
+                    |  ‘for’ Type ‘=’ Expr
 Template          ::=  InheritClauses [TemplateBody]                            Template(constr, parents, self, stats)
 InheritClauses    ::=  [‘extends’ ConstrApps] [‘derives’ QualId {‘,’ QualId}]
 ConstrApps        ::=  ConstrApp {‘with’ ConstrApp}

docs/docs/reference/contextual/inferable-params.md

@@ -41,8 +41,7 @@ def maximum[T](xs: List[T]) given Ord[T]: T =
 inferred argument to `max`. The name of the parameter is left out.
 
 Generally, inferable parameters may be given either as a parameter list `(p_1: T_1, ..., p_n: T_n)`
-or as a sequence of types, separated by commas. To distinguish the two, a leading
-`(` always indicates a parameter list.
+or as a sequence of types, separated by commas.
 
 ## Inferring Complex Arguments
 
@@ -101,11 +100,11 @@ Functions like `the` that have only inferable parameters are also called _contex
 Here is the new syntax of parameters and arguments seen as a delta from the [standard context free syntax of Scala 3](http://dotty.epfl.ch/docs/internals/syntax.html).
 ```
 ClsParamClause    ::=  ...
-                    |  ‘given’ (‘(’ [ClsParams] ‘)’ | ContextTypes)
+                    |  ‘given’ (‘(’ [ClsParams] ‘)’ | GivenTypes)
 DefParamClause    ::=  ...
-                    |  InferParamClause
-InferParamClause  ::=  ‘given’ (‘(’ DefParams ‘)’ | ContextTypes)
-ContextTypes      ::=  RefinedType {‘,’ RefinedType}
+                    |  GivenParamClause
+GivenParamClause  ::=  ‘given’ (‘(’ DefParams ‘)’ | GivenTypes)
+GivenTypes        ::=  AnnotType {‘,’ AnnotType}
 
 InfixExpr         ::=  ...
                     |  InfixExpr ‘given’ (InfixExpr | ParArgumentExprs)

docs/docs/reference/contextual/instance-defs.md

@@ -67,11 +67,11 @@ Here is the new syntax of implied instance definitions, seen as a delta from the
 TmplDef          ::=  ...
                   |  ‘implied’ InstanceDef
 InstanceDef      ::=  [id] InstanceParams InstanceBody
-InstanceParams   ::=  [DefTypeParamClause] {InferParamClause}
-InferParamClause ::=  ‘given’ (‘(’ [DefParams] ‘)’ | ContextTypes)
+InstanceParams   ::=  [DefTypeParamClause] {GivenParamClause}
+GivenParamClause ::=  ‘given’ (‘(’ [DefParams] ‘)’ | GivenTypes)
 InstanceBody     ::=  [‘for’ ConstrApp {‘,’ ConstrApp }] [TemplateBody]
                    |  ‘for’ Type ‘=’ Expr
-ContextTypes     ::=  RefinedType {‘,’ RefinedType}
+GivenTypes       ::=  AnnotType {‘,’ AnnotType}
 ```
 The identifier `id` can be omitted only if either the `for` part or the template body is present.
 If the `for` part is missing, the template body must define at least one extension method.

tests/pos-special/fatal-warnings/i6290.scala

@@ -0,0 +1,15 @@
+class TC { type T }
+
+class C given (TC { type T = Int })
+
+def f1 given (x: TC) = ???
+def f2 given (@unchecked x: TC) = ???
+inline def f3 given (inline x: TC) = ???
+
+class C1 given (x: TC)
+class C2 given (@unchecked x: TC)
+class C3 given (val x: TC)
+class C4 given (var x: TC)
+class C5 given (private val x: TC)
+class C6 given (private[this] val x: TC)
+

tests/run/i2567.check

@@ -0,0 +1,6 @@
+hi
+hi
+hi
+hi
+hi
+hi

tests/run/i2567.scala

@@ -0,0 +1,15 @@
+class TC
+implied tc for TC
+
+class Foo given TC {
+  println("hi")
+}
+
+object Test extends App {
+  new Foo
+  new Foo given tc
+  new Foo()
+  new Foo() given tc
+  Foo()
+  Foo() given tc
+}