Support type variable definitions in quoted patterns

Author: nicolasstucki

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

@@ -1585,6 +1585,19 @@ object Parsers {
             t
     end typ
 
+    /** TypeBlock ::= {TypeBlockStat semi} Type
+     *  TypeBlockStat     ::=  ‘type’ {nl} TypeDcl
+     */
+    def typeBlock(): Tree =
+      val tDefs = new ListBuffer[Tree]
+      while in.token == TYPE do
+        val mods = defAnnotsMods(modifierTokens)
+        tDefs += typeDefOrDcl(in.offset, in.skipToken(mods))
+        acceptStatSep()
+      val tpt = typ()
+      if tDefs.isEmpty then tpt else Block(tDefs.toList, tpt)
+
+
     private def makeKindProjectorTypeDef(name: TypeName): TypeDef = {
       val isVarianceAnnotated = name.startsWith("+") || name.startsWith("-")
       // We remove the variance marker from the name without passing along the specified variance at all
@@ -2447,7 +2460,7 @@ object Parsers {
           atSpan(in.skipToken()) {
             withinStaged(StageKind.Quoted | (if (location.inPattern) StageKind.QuotedPattern else 0)) {
               Quote {
-                if (in.token == LBRACKET) inBrackets(typ())
+                if (in.token == LBRACKET) inBrackets(typeBlock())
                 else stagedBlock()
               }
             }
@@ -3080,8 +3093,8 @@ object Parsers {
  /* -------- PARAMETERS ------------------------------------------- */
 
     /** DefParamClauses       ::= DefParamClause { DefParamClause }  -- and two DefTypeParamClause cannot be adjacent
-     *  DefParamClause        ::= DefTypeParamClause 
-     *                          | DefTermParamClause 
+     *  DefParamClause        ::= DefTypeParamClause
+     *                          | DefTermParamClause
      *                          | UsingParamClause
      */
     def typeOrTermParamClauses(
@@ -3179,7 +3192,7 @@ object Parsers {
      *  UsingClsTermParamClause::= ‘(’ ‘using’ [‘erased’] (ClsParams | ContextTypes) ‘)’
      *  ClsParams         ::=  ClsParam {‘,’ ClsParam}
      *  ClsParam          ::=  {Annotation}
-     * 
+     *
      *  TypelessClause    ::= DefTermParamClause
      *                      | UsingParamClause
      *
@@ -3557,13 +3570,13 @@ object Parsers {
       }
     }
 
-    
+
 
     /** DefDef  ::=  DefSig [‘:’ Type] ‘=’ Expr
      *            |  this TypelessClauses [DefImplicitClause] `=' ConstrExpr
      *  DefDcl  ::=  DefSig `:' Type
      *  DefSig  ::=  id [DefTypeParamClause] DefTermParamClauses
-     * 
+     *
      * if clauseInterleaving is enabled:
      *  DefSig  ::=  id [DefParamClauses] [DefImplicitClause]
      */
@@ -3602,8 +3615,8 @@ object Parsers {
         val mods1 = addFlag(mods, Method)
         val ident = termIdent()
         var name = ident.name.asTermName
-        val paramss = 
-          if in.featureEnabled(Feature.clauseInterleaving) then 
+        val paramss =
+          if in.featureEnabled(Feature.clauseInterleaving) then
             // If you are making interleaving stable manually, please refer to the PR introducing it instead, section "How to make non-experimental"
             typeOrTermParamClauses(ParamOwner.Def, numLeadParams = numLeadParams)
           else
@@ -3613,7 +3626,7 @@ object Parsers {
             joinParams(tparams, vparamss)
 
         var tpt = fromWithinReturnType { typedOpt() }
-        
+
         if (migrateTo3) newLineOptWhenFollowedBy(LBRACE)
         val rhs =
           if in.token == EQUALS then

compiler/src/dotty/tools/dotc/typer/QuotesAndSplices.scala

@@ -197,11 +197,11 @@ trait QuotesAndSplices {
    *  )
    *  ```
    */
-  private def splitQuotePattern(quoted: Tree)(using Context): (Map[Symbol, Bind], Tree, List[Tree]) = {
+  private def splitQuotePattern(quoted: Tree)(using Context): (Map[Symbol, Tree], Tree, List[Tree]) = {
     val ctx0 = ctx
 
-    val typeBindings: collection.mutable.Map[Symbol, Bind] = collection.mutable.Map.empty
-    def getBinding(sym: Symbol): Bind =
+    val typeBindings: collection.mutable.Map[Symbol, Tree] = collection.mutable.Map.empty
+    def getBinding(sym: Symbol): Tree =
       typeBindings.getOrElseUpdate(sym, {
         val bindingBounds = sym.info
         val bsym = newPatternBoundSymbol(sym.name.toString.stripPrefix("$").toTypeName, bindingBounds, quoted.span)
@@ -395,7 +395,10 @@ trait QuotesAndSplices {
     val quoted0 = desugar.quotedPattern(quoted, untpd.TypedSplice(TypeTree(quotedPt)))
     val quoteCtx = quoteContext.addMode(Mode.QuotedPattern).retractMode(Mode.Pattern)
     val quoted1 =
-      if quoted.isType then typedType(quoted0, WildcardType)(using quoteCtx)
+      if quoted.isType then typedType(quoted0, WildcardType)(using quoteCtx) match
+        case quoted1 @ Block(stats, Typed(tpt, _)) => cpy.Block(quoted1)(stats, tpt)
+        case quoted1 => quoted1
+
       else typedExpr(quoted0, WildcardType)(using quoteCtx)
 
     val (typeBindings, shape, splices) = splitQuotePattern(quoted1)

docs/_docs/reference/syntax.md

@@ -274,7 +274,7 @@ ColonArgument     ::=  colon [LambdaStart]
 LambdaStart       ::=  FunParams (‘=>’ | ‘?=>’)
                     |  HkTypeParamClause ‘=>’
 Quoted            ::=  ‘'’ ‘{’ Block ‘}’
-                    |  ‘'’ ‘[’ Type ‘]’
+                    |  ‘'’ ‘[’ TypeBlock ‘]’
 ExprSplice        ::= spliceId                                                  -- if inside quoted block
                     |  ‘$’ ‘{’ Block ‘}’                                        -- unless inside quoted pattern
                     |  ‘$’ ‘{’ Pattern ‘}’                                      -- when inside quoted pattern
@@ -293,6 +293,8 @@ BlockStat         ::=  Import
                     |  Extension
                     |  Expr1
                     |  EndMarker
+TypeBlock         ::=  {TypeBlockStat semi} Type
+TypeBlockStat     ::=  ‘type’ {nl} TypeDcl
 
 ForExpr           ::=  ‘for’ ‘(’ Enumerators0 ‘)’ {nl} [‘do‘ | ‘yield’] Expr
                     |  ‘for’ ‘{’ Enumerators0 ‘}’ {nl} [‘do‘ | ‘yield’] Expr

tests/pos-macros/i10864a/Macro_1.scala

@@ -0,0 +1,19 @@
+import scala.quoted._
+
+case class T(t: Type[_])
+
+object T {
+  def impl[T <: AnyKind](using tt: Type[T])(using Quotes): Expr[Unit] = {
+    val t = T(tt)
+    t.t match
+      case '[type x; `x`] =>
+        assert(Type.show[x] == "scala.Int", Type.show[x])
+      case '[type f[X]; `f`] =>
+        assert(Type.show[f] == "[A >: scala.Nothing <: scala.Any] => scala.collection.immutable.List[A]", Type.show[f])
+      case '[type f <: AnyKind; `f`] =>
+        assert(Type.show[f] == "[K >: scala.Nothing <: scala.Any, V >: scala.Nothing <: scala.Any] => scala.collection.immutable.Map[K, V]", Type.show[f])
+    '{}
+  }
+
+  inline def run[T <: AnyKind] = ${ impl[T] }
+}

tests/pos-macros/i10864a/Test_2.scala

@@ -0,0 +1,5 @@
+@main
+def run =
+  T.run[Int]
+  T.run[List]
+  T.run[Map]

tests/pos-macros/i7264.scala

@@ -3,5 +3,6 @@ class Foo {
   def f[T2](t: Type[T2])(using Quotes) = t match {
     case '[ *:[Int, t2] ] =>
       Type.of[ *:[Int, t2] ]
+    case '[ type t <: Tuple; *:[`t`, `t`] ] =>
   }
 }