SI-6844 restrict splicing in parameter position

Previously were a bit too permissive on how splicing in function
parameter position worked. This made confusing things like
possible:

   val x = TermName(“x”)
   q”def foo($x)”

Now you can either splice trees in that position (ValDefs) or
you have to provide type if you splice a name.

7 files changed, 106 insertions, 82 deletions

diff --git a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
index d122a1a207..b13d676c65 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
@@ -2121,8 +2121,6 @@ self =>
 
 /* -------- PARAMETERS ------------------------------------------- */
 
-    def allowTypelessParams = false
-
     /** {{{
      *  ParamClauses      ::= {ParamClause} [[nl] `(' implicit Params `)']
      *  ParamClause       ::= [nl] `(' [Params] `)'
@@ -2137,56 +2135,6 @@ self =>
     def paramClauses(owner: Name, contextBounds: List[Tree], ofCaseClass: Boolean): List[List[ValDef]] = {
       var implicitmod = 0
       var caseParam = ofCaseClass
-      def param(): ValDef = {
-        val start = in.offset
-        val annots = annotations(skipNewLines = false)
-        var mods = Modifiers(Flags.PARAM)
-        if (owner.isTypeName) {
-          mods = modifiers() | Flags.PARAMACCESSOR
-          if (mods.isLazy) syntaxError("lazy modifier not allowed here. Use call-by-name parameters instead", skipIt = false)
-          in.token match {
-            case v @ (VAL | VAR) =>
-              mods = mods withPosition (in.token.toLong, tokenRange(in))
-              if (v == VAR) mods |= Flags.MUTABLE
-              in.nextToken()
-            case _ =>
-              if (mods.flags != Flags.PARAMACCESSOR) accept(VAL)
-              if (!caseParam) mods |= Flags.PrivateLocal
-          }
-          if (caseParam) mods |= Flags.CASEACCESSOR
-        }
-        val nameOffset = in.offset
-        val name = ident()
-        var bynamemod = 0
-        val tpt =
-          if (((settings.YmethodInfer && !owner.isTypeName) || allowTypelessParams) && in.token != COLON) {
-            TypeTree()
-          } else { // XX-METHOD-INFER
-            accept(COLON)
-            if (in.token == ARROW) {
-              if (owner.isTypeName && !mods.hasLocalFlag)
-                syntaxError(
-                  in.offset,
-                  (if (mods.isMutable) "`var'" else "`val'") +
-                  " parameters may not be call-by-name", skipIt = false)
-              else if (implicitmod != 0)
-                syntaxError(
-                  in.offset,
-                  "implicit parameters may not be call-by-name", skipIt = false)
-              else bynamemod = Flags.BYNAMEPARAM
-            }
-            paramType()
-          }
-        val default =
-          if (in.token == EQUALS) {
-            in.nextToken()
-            mods |= Flags.DEFAULTPARAM
-            expr()
-          } else EmptyTree
-        atPos(start, if (name == nme.ERROR) start else nameOffset) {
-          ValDef((mods | implicitmod.toLong | bynamemod) withAnnotations annots, name.toTermName, tpt, default)
-        }
-      }
       def paramClause(): List[ValDef] = {
         if (in.token == RPAREN)
           return Nil
@@ -2195,7 +2143,7 @@ self =>
           in.nextToken()
           implicitmod = Flags.IMPLICIT
         }
-        commaSeparated(param())
+        commaSeparated(param(owner, implicitmod, caseParam  ))
       }
       val vds = new ListBuffer[List[ValDef]]
       val start = in.offset
@@ -2243,6 +2191,57 @@ self =>
       }
     }
 
+    def param(owner: Name, implicitmod: Int, caseParam: Boolean): ValDef = {
+      val start = in.offset
+      val annots = annotations(skipNewLines = false)
+      var mods = Modifiers(Flags.PARAM)
+      if (owner.isTypeName) {
+        mods = modifiers() | Flags.PARAMACCESSOR
+        if (mods.isLazy) syntaxError("lazy modifier not allowed here. Use call-by-name parameters instead", skipIt = false)
+        in.token match {
+          case v @ (VAL | VAR) =>
+            mods = mods withPosition (in.token.toLong, tokenRange(in))
+            if (v == VAR) mods |= Flags.MUTABLE
+            in.nextToken()
+          case _ =>
+            if (mods.flags != Flags.PARAMACCESSOR) accept(VAL)
+            if (!caseParam) mods |= Flags.PrivateLocal
+        }
+        if (caseParam) mods |= Flags.CASEACCESSOR
+      }
+      val nameOffset = in.offset
+      val name = ident()
+      var bynamemod = 0
+      val tpt =
+        if ((settings.YmethodInfer && !owner.isTypeName) && in.token != COLON) {
+          TypeTree()
+        } else { // XX-METHOD-INFER
+          accept(COLON)
+          if (in.token == ARROW) {
+            if (owner.isTypeName && !mods.hasLocalFlag)
+              syntaxError(
+                in.offset,
+                (if (mods.isMutable) "`var'" else "`val'") +
+                " parameters may not be call-by-name", skipIt = false)
+            else if (implicitmod != 0)
+              syntaxError(
+                in.offset,
+                "implicit parameters may not be call-by-name", skipIt = false)
+            else bynamemod = Flags.BYNAMEPARAM
+          }
+          paramType()
+        }
+      val default =
+        if (in.token == EQUALS) {
+          in.nextToken()
+          mods |= Flags.DEFAULTPARAM
+          expr()
+        } else EmptyTree
+      atPos(start, if (name == nme.ERROR) start else nameOffset) {
+        ValDef((mods | implicitmod.toLong | bynamemod) withAnnotations annots, name.toTermName, tpt, default)
+      }
+    }
+
     /** {{{
      *  TypeParamClauseOpt    ::= [TypeParamClause]
      *  TypeParamClause       ::= `[' VariantTypeParam {`,' VariantTypeParam} `]']
diff --git a/src/compiler/scala/tools/reflect/quasiquotes/Parsers.scala b/src/compiler/scala/tools/reflect/quasiquotes/Parsers.scala
index 6e6b617e5c..7604f779d6 100644
--- a/src/compiler/scala/tools/reflect/quasiquotes/Parsers.scala
+++ b/src/compiler/scala/tools/reflect/quasiquotes/Parsers.scala
@@ -80,8 +80,20 @@ trait Parsers { self: Quasiquotes =>
       }
       import treeBuilder.{global => _, unit => _, _}
 
+      def quasiquoteParam(name: Name, flags: FlagSet = NoFlags) =
+        ValDef(Modifiers(flags), name.toTermName, Ident(tpnme.QUASIQUOTE_PARAM), EmptyTree)
+
       // q"def foo($x)"
-      override def allowTypelessParams = true
+      override def param(owner: Name, implicitmod: Int, caseParam: Boolean): ValDef =
+        if (isHole && lookingAhead { in.token == COMMA || in.token == RPAREN }) {
+          quasiquoteParam(ident(), implicitmod)
+        } else super.param(owner, implicitmod, caseParam)
+
+      // q"($x) => ..." && q"class X { selfie => }
+      override def convertToParam(tree: Tree): ValDef = tree match {
+        case Ident(name) if isHole(name) => quasiquoteParam(name)
+        case _ => super.convertToParam(tree)
+      }
 
       // q"foo match { case $x }"
       override def caseClause(): CaseDef =
@@ -193,4 +205,4 @@ trait Parsers { self: Quasiquotes =>
   }
 
   object FreshName extends FreshNameExtractor(nme.QUASIQUOTE_PREFIX)
-}
\ No newline at end of file
+}
diff --git a/src/compiler/scala/tools/reflect/quasiquotes/Placeholders.scala b/src/compiler/scala/tools/reflect/quasiquotes/Placeholders.scala
index bdb44ad9a2..5669ec731f 100644
--- a/src/compiler/scala/tools/reflect/quasiquotes/Placeholders.scala
+++ b/src/compiler/scala/tools/reflect/quasiquotes/Placeholders.scala
@@ -95,7 +95,6 @@ trait Placeholders { self: Quasiquotes =>
       case Ident(name) => name
       case Bind(name, Ident(nme.WILDCARD)) => name
       case TypeDef(_, name, List(), TypeBoundsTree(EmptyTree, EmptyTree)) => name
-      case ValDef(_, name, TypeTree(), EmptyTree) => name
     }
   }
 
@@ -111,6 +110,12 @@ trait Placeholders { self: Quasiquotes =>
     }
   }
 
+  object ParamPlaceholder extends HolePlaceholder {
+    def matching = {
+      case ValDef(_, name, Ident(tpnme.QUASIQUOTE_PARAM), EmptyTree) => name
+    }
+  }
+
   object TuplePlaceholder {
     def unapply(tree: Tree): Option[List[Tree]] = tree match {
       case Apply(Ident(nme.QUASIQUOTE_TUPLE), args) => Some(args)
diff --git a/src/compiler/scala/tools/reflect/quasiquotes/Reifiers.scala b/src/compiler/scala/tools/reflect/quasiquotes/Reifiers.scala
index 87ab52414c..58baad01a1 100644
--- a/src/compiler/scala/tools/reflect/quasiquotes/Reifiers.scala
+++ b/src/compiler/scala/tools/reflect/quasiquotes/Reifiers.scala
@@ -137,6 +137,7 @@ trait Reifiers { self: Quasiquotes =>
       case RefineStatPlaceholder(hole) => reifyRefineStat(hole)
       case EarlyDefPlaceholder(hole) => reifyEarlyDef(hole)
       case PackageStatPlaceholder(hole) => reifyPackageStat(hole)
+      case ParamPlaceholder(hole) => hole.tree
       // for enumerators are checked not during splicing but during
       // desugaring of the for loop in SyntacticFor & SyntacticForYield
       case ForEnumPlaceholder(hole) => hole.tree
@@ -311,6 +312,8 @@ trait Reifiers { self: Quasiquotes =>
       case EarlyDefPlaceholder(h @ Hole(_, DotDot)) => reifyEarlyDef(h)
       case PackageStatPlaceholder(h @ Hole(_, DotDot)) => reifyPackageStat(h)
       case ForEnumPlaceholder(Hole(tree, DotDot)) => tree
+      case ParamPlaceholder(Hole(tree, DotDot)) => tree
+      case List(ParamPlaceholder(Hole(tree, DotDotDot))) => tree
       case List(Placeholder(Hole(tree, DotDotDot))) => tree
     } {
       reify(_)
diff --git a/src/reflect/scala/reflect/api/BuildUtils.scala b/src/reflect/scala/reflect/api/BuildUtils.scala
index 6971175f88..89492e75c4 100644
--- a/src/reflect/scala/reflect/api/BuildUtils.scala
+++ b/src/reflect/scala/reflect/api/BuildUtils.scala
@@ -126,8 +126,8 @@ private[reflect] trait BuildUtils { self: Universe =>
 
     trait SyntacticClassDefExtractor {
       def apply(mods: Modifiers, name: TypeName, tparams: List[Tree],
-                constrMods: Modifiers, vparamss: List[List[Tree]], earlyDefs: List[Tree],
-                parents: List[Tree], selfType: Tree, body: List[Tree]): ClassDef
+                constrMods: Modifiers, vparamss: List[List[Tree]],
+                earlyDefs: List[Tree], parents: List[Tree], selfType: Tree, body: List[Tree]): ClassDef
       def unapply(tree: Tree): Option[(Modifiers, TypeName, List[TypeDef], Modifiers, List[List[ValDef]],
                                        List[Tree], List[Tree], ValDef, List[Tree])]
     }
@@ -197,9 +197,10 @@ private[reflect] trait BuildUtils { self: Universe =>
     val SyntacticDefDef: SyntacticDefDefExtractor
 
     trait SyntacticDefDefExtractor {
-      def apply(mods: Modifiers, name: TermName, tparams: List[Tree], vparamss: List[List[Tree]], tpt: Tree, rhs: Tree): DefDef
+      def apply(mods: Modifiers, name: TermName, tparams: List[Tree],
+                vparamss: List[List[Tree]], tpt: Tree, rhs: Tree): DefDef
 
-      def unapply(tree: Tree): Option[(Modifiers, TermName, List[Tree], List[List[ValDef]], Tree, Tree)]
+      def unapply(tree: Tree): Option[(Modifiers, TermName, List[TypeDef], List[List[ValDef]], Tree, Tree)]
     }
 
     val SyntacticValDef: SyntacticValDefExtractor
diff --git a/src/reflect/scala/reflect/internal/BuildUtils.scala b/src/reflect/scala/reflect/internal/BuildUtils.scala
index 0a81bfa2a5..657b098952 100644
--- a/src/reflect/scala/reflect/internal/BuildUtils.scala
+++ b/src/reflect/scala/reflect/internal/BuildUtils.scala
@@ -71,15 +71,18 @@ trait BuildUtils { self: SymbolTable =>
 
     def mkAnnotation(trees: List[Tree]): List[Tree] = trees.map(mkAnnotation)
 
-    def mkVparamss(argss: List[List[Tree]]): List[List[ValDef]] = argss.map(_.map(mkParam))
+    def mkParam(argss: List[List[Tree]], extraFlags: FlagSet = NoFlags): List[List[ValDef]] =
+      argss.map { args => args.map { mkParam(_, extraFlags) } }
 
-    def mkParam(tree: Tree): ValDef = tree match {
+    def mkParam(tree: Tree, extraFlags: FlagSet): ValDef = tree match {
+      case Typed(Ident(name: TermName), tpt) =>
+        mkParam(ValDef(NoMods, name, tpt, EmptyTree), extraFlags)
       case vd: ValDef =>
-        var newmods = (vd.mods | PARAM) & (~DEFERRED)
+        var newmods = vd.mods & (~DEFERRED)
         if (vd.rhs.nonEmpty) newmods |= DEFAULTPARAM
-        copyValDef(vd)(mods = newmods)
+        copyValDef(vd)(mods = newmods | extraFlags)
       case _ =>
-        throw new IllegalArgumentException(s"$tree is not valid represenation of function parameter, " +
+        throw new IllegalArgumentException(s"$tree is not valid represenation of a parameter, " +
                                             """consider reformatting it into q"val $name: $T = $default" shape""")
     }
 
@@ -239,14 +242,10 @@ trait BuildUtils { self: SymbolTable =>
 
     object SyntacticClassDef extends SyntacticClassDefExtractor {
       def apply(mods: Modifiers, name: TypeName, tparams: List[Tree],
-                constrMods: Modifiers, vparamss: List[List[Tree]], earlyDefs: List[Tree],
-                parents: List[Tree], selfType: Tree, body: List[Tree]): ClassDef = {
+                constrMods: Modifiers, vparamss: List[List[Tree]],
+                earlyDefs: List[Tree], parents: List[Tree], selfType: Tree, body: List[Tree]): ClassDef = {
         val extraFlags = PARAMACCESSOR | (if (mods.isCase) CASEACCESSOR else 0L)
-        val vparamss0 = vparamss.map { _.map {
-          case vd: ValDef => copyValDef(vd)(mods = (vd.mods | extraFlags) & (~DEFERRED))
-          case tree => throw new IllegalArgumentException(s"$tree is not valid representation of class parameter, " +
-                                                          """consider reformatting it into q"val $name: $T = $default" shape""")
-        } }
+        val vparamss0 = mkParam(vparamss, extraFlags)
         val tparams0 = mkTparams(tparams)
         val parents0 = gen.mkParents(mods,
           if (mods.isCase) parents.filter {
@@ -393,7 +392,7 @@ trait BuildUtils { self: SymbolTable =>
 
     object SyntacticFunction extends SyntacticFunctionExtractor {
       def apply(params: List[Tree], body: Tree): Tree = {
-        val params0 :: Nil = mkVparamss(params :: Nil)
+        val params0 :: Nil = mkParam(params :: Nil, PARAM)
         require(params0.forall { _.rhs.isEmpty }, "anonymous functions don't support parameters with default values")
         Function(params0, body)
       }
@@ -420,11 +419,15 @@ trait BuildUtils { self: SymbolTable =>
     }
 
     object SyntacticDefDef extends SyntacticDefDefExtractor {
-      def apply(mods: Modifiers, name: TermName, tparams: List[Tree], vparamss: List[List[Tree]], tpt: Tree, rhs: Tree): DefDef =
-        DefDef(mods, name, mkTparams(tparams), mkVparamss(vparamss), tpt, rhs)
+      def apply(mods: Modifiers, name: TermName, tparams: List[Tree],
+                vparamss: List[List[Tree]], tpt: Tree, rhs: Tree): DefDef = {
+        val vparamss0 = mkParam(vparamss, PARAM)
+        DefDef(mods, name, mkTparams(tparams), vparamss0, tpt, rhs)
+      }
 
-      def unapply(tree: Tree): Option[(Modifiers, TermName, List[Tree], List[List[ValDef]], Tree, Tree)] = tree match {
-        case DefDef(mods, name, tparams, vparamss, tpt, rhs) => Some((mods, name, tparams, vparamss, tpt, rhs))
+      def unapply(tree: Tree): Option[(Modifiers, TermName, List[TypeDef], List[List[ValDef]], Tree, Tree)] = tree match {
+        case DefDef(mods, name, tparams, vparamss, tpt, rhs) =>
+          Some((mods, name, tparams, vparamss, tpt, rhs))
         case _ => None
       }
     }
diff --git a/src/reflect/scala/reflect/internal/StdNames.scala b/src/reflect/scala/reflect/internal/StdNames.scala
index a54aa1f6e8..73ad9def73 100644
--- a/src/reflect/scala/reflect/internal/StdNames.scala
+++ b/src/reflect/scala/reflect/internal/StdNames.scala
@@ -250,12 +250,13 @@ trait StdNames {
     final val Quasiquote: NameType          = "Quasiquote"
 
     // quasiquote-specific names
-    final val QUASIQUOTE_MODS: NameType         = "$quasiquote$mods$"
-    final val QUASIQUOTE_TUPLE: NameType        = "$quasiquote$tuple$"
-    final val QUASIQUOTE_FUNCTION: NameType     = "$quasiquote$function$"
-    final val QUASIQUOTE_REFINE_STAT: NameType  = "$quasiquote$refine$stat$"
     final val QUASIQUOTE_EARLY_DEF: NameType    = "$quasiquote$early$def$"
+    final val QUASIQUOTE_FUNCTION: NameType     = "$quasiquote$function$"
+    final val QUASIQUOTE_MODS: NameType         = "$quasiquote$mods$"
     final val QUASIQUOTE_PACKAGE_STAT: NameType = "$quasiquote$package$stat$"
+    final val QUASIQUOTE_PARAM: NameType        = "$quasiquote$param$"
+    final val QUASIQUOTE_REFINE_STAT: NameType  = "$quasiquote$refine$stat$"
+    final val QUASIQUOTE_TUPLE: NameType        = "$quasiquote$tuple$"
 
     // Annotation simple names, used in Namer
     final val BeanPropertyAnnot: NameType = "BeanProperty"
@@ -703,9 +704,9 @@ trait StdNames {
     val materializeTypeTag: NameType   = "materializeTypeTag"
     val moduleClass : NameType         = "moduleClass"
     val mkAnnotation: NameType         = "mkAnnotation"
-    val mkRefineStat: NameType         = "mkRefineStat"
     val mkEarlyDef: NameType           = "mkEarlyDef"
     val mkPackageStat: NameType        = "mkPackageStat"
+    val mkRefineStat: NameType         = "mkRefineStat"
     val ne: NameType                   = "ne"
     val newArray: NameType             = "newArray"
     val newFreeTerm: NameType          = "newFreeTerm"