Fix #7264: Propagate prototypes in quoted type patterns

Author: odersky

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

@@ -98,7 +98,7 @@ trait QuotesAndSplices {
  case _ =>
  }
  if (ctx.mode.is(Mode.QuotedPattern) && level == 1)
- if (isFullyDefined(pt, ForceDegree.all)) {
+ if (false && isFullyDefined(pt, ForceDegree.all)) {
  ctx.error(i"Spliced type pattern must not be fully defined. Consider using $pt directly", tree.expr.sourcePos)
  tree.withType(UnspecifiedErrorType)
  }
@@ -111,7 +111,10 @@ trait QuotesAndSplices {
  ctx.error("expected a name binding", expr.sourcePos)
  "$error".toTypeName
  }
- val typeSym = ctx.newSymbol(spliceOwner(ctx), name, EmptyFlags, TypeBounds.empty, NoSymbol, tree.expr.span)
+ val typeSymInfo = pt match
+ case pt: TypeBounds => pt
+ case _ => TypeBounds.empty
+ val typeSym = ctx.newSymbol(spliceOwner(ctx), name, EmptyFlags, typeSymInfo, NoSymbol, tree.expr.span)
  typeSym.addAnnotation(Annotation(New(ref(defn.InternalQuoted_patternBindHoleAnnot.typeRef)).withSpan(tree.expr.span)))
  val pat = typedPattern(tree.expr, defn.QuotedTypeClass.typeRef.appliedTo(typeSym.typeRef))(
  spliceContext.retractMode(Mode.QuotedPattern).withOwner(spliceOwner(ctx)))
@@ -317,13 +320,16 @@ trait QuotesAndSplices {
  ctx.error(missingArgMsg(qctx, defn.QuoteContextClass.typeRef, ""), ctx.source.atSpan(tree.span))
 
  val quoted = tree.quoted
- val exprPt = pt.baseType(defn.QuotedExprClass)
+ val exprPt = pt.baseType(if quoted.isType then defn.QuotedTypeClass else defn.QuotedExprClass)
  val quotedPt = exprPt.argInfos.headOption match {
  case Some(argPt: ValueType) => argPt // excludes TypeBounds
  case _ => defn.AnyType
  }
  val quoted0 = desugar.quotedPattern(quoted, untpd.TypedSplice(TypeTree(quotedPt)))
- val quoted1 = typedExpr(quoted0, WildcardType)(quoteContext.addMode(Mode.QuotedPattern))
+ val quoteCtx = quoteContext.addMode(Mode.QuotedPattern)
+ val quoted1 =
+ if quoted.isType then typedType(quoted0, quotedPt)(quoteCtx)
+ else typedExpr(quoted0, quotedPt)(quoteCtx)
 
  val (typeBindings, shape, splices) = splitQuotePattern(quoted1)
 

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

@@ -1389,7 +1389,7 @@ class Typer extends Namer
  def typedArg(arg: untpd.Tree, tparam: ParamInfo) = {
  def tparamBounds = tparam.paramInfoAsSeenFrom(tpt1.tpe.appliedTo(tparams.map(_ => TypeBounds.empty)))
  val (desugaredArg, argPt) =
- if (ctx.mode is Mode.Pattern)
+ if ctx.mode.is(Mode.Pattern) || ctx.mode.is(Mode.QuotedPattern) then
  (if (untpd.isVarPattern(arg)) desugar.patternVar(arg) else arg, tparamBounds)
  else
  (arg, WildcardType)
@@ -2177,7 +2177,7 @@ class Typer extends Namer
 
  /** Typecheck and adapt tree, returning a typed tree. Parameters as for `typedUnadapted` */
  def typed(tree: untpd.Tree, pt: Type, locked: TypeVars)(implicit ctx: Context): Tree =
- trace(i"typing $tree", typr, show = true) {
+ trace(i"typing $tree, pt = $pt", typr, show = true) {
  record(s"typed $getClass")
  record("typed total")
  assertPositioned(tree)

tests/pos/i7264.scala

@@ -0,0 +1,6 @@
+import scala.quoted._
+class Foo {
+ def f[T2](t: Type[T2])(given QuoteContext) = t match {
+ case '[ *:[Int, $t] ] =>
+ }
+}