Keep tree of type ascriptions of quote pattern splices

compiler/src/dotty/tools/dotc/transform/PostTyper.scala

@@ -492,18 +492,9 @@ class PostTyper extends MacroTransform with InfoTransformer { thisPhase =>
           )
         case Block(_, Closure(_, _, tpt)) if ExpandSAMs.needsWrapperClass(tpt.tpe) =>
           superAcc.withInvalidCurrentClass(super.transform(tree))
-        case _: Quote =>
+        case _: Quote | _: QuotePattern =>
           ctx.compilationUnit.needsStaging = true
           super.transform(tree)
-        case _: QuotePattern =>
-          if !ctx.reporter.errorsReported then
-            Checking.checkAppliedTypesIn(TypeTree(tree.tpe).withSpan(tree.span))
-          ctx.compilationUnit.needsStaging = true
-          super.transform(tree)
-        case tree: SplicePattern =>
-          if !ctx.reporter.errorsReported then
-            Checking.checkAppliedTypesIn(TypeTree(tree.tpe).withSpan(tree.span))
-          super.transform(tree)
         case tree =>
           super.transform(tree)
       }

compiler/src/dotty/tools/dotc/transform/patmat/Space.scala

@@ -312,7 +312,7 @@ object SpaceEngine {
   def isIrrefutableQuotePattern(pat: tpd.QuotePattern, pt: Type)(using Context): Boolean = {
     if pat.body.isType then pat.bindings.isEmpty && pt =:= pat.tpe
     else pat.body match
-      case _: SplicePattern => pat.bindings.isEmpty && pt <:< pat.tpe
+      case _: SplicePattern | Typed(_: SplicePattern, _) => pat.bindings.isEmpty && pt <:< pat.tpe
       case _ => false
   }
 

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

@@ -259,14 +259,8 @@ trait QuotesAndSplices {
             pat.symbol.addAnnotation(Annotation(New(ref(defn.QuotedRuntimePatterns_fromAboveAnnot.typeRef)).withSpan(pat.span)))
           allTypeBindings += pat
           TypeTree(pat.symbol.typeRef).withSpan(pat.span)
-
-        case Typed(splice: SplicePattern, tpt) if !tpt.tpe.derivesFrom(defn.RepeatedParamClass) =>
-          // We drop the type ascription because it is redundant, the SplicePattern contains the same type
-          transform(tpt) // Collect type bindings
-          splice
         case _: SplicePattern =>
           tree
-
         case _ =>
           super.transform(tree)
     }

tests/neg-macros/quote-type-variable-no-inference-2.check

@@ -5,9 +5,9 @@
   |
   |                      Consider defining bounds explicitly:
   |                        '{ type t <: Int & Double; ... }
--- [E057] Type Mismatch Error: tests/neg-macros/quote-type-variable-no-inference-2.scala:5:12 --------------------------
+-- [E057] Type Mismatch Error: tests/neg-macros/quote-type-variable-no-inference-2.scala:5:20 --------------------------
 5 |    case '{ $_ : F[t, t]; () } => // warn // error
-  |            ^
-  |            Type argument t does not conform to upper bound Double in inferred type F[t, t]
+  |                    ^
+  |                    Type argument t does not conform to upper bound Double
   |
   | longer explanation available when compiling with `-explain`

tests/neg-macros/quote-type-variable-no-inference-3.check

@@ -12,9 +12,9 @@
   |
   |                                                 Consider defining bounds explicitly:
   |                                                   '{ type u <: Comparable[u] & Comparable[Any]; ... }
--- [E057] Type Mismatch Error: tests/neg-macros/quote-type-variable-no-inference-3.scala:5:12 --------------------------
+-- [E057] Type Mismatch Error: tests/neg-macros/quote-type-variable-no-inference-3.scala:5:20 --------------------------
 5 |    case '{ $_ : F[t, t]; () } => // warn // error
-  |            ^
-  |            Type argument t does not conform to upper bound Comparable[t] in inferred type F[t, t]
+  |                    ^
+  |                    Type argument t does not conform to upper bound Comparable[t]
   |
   | longer explanation available when compiling with `-explain`

tests/neg-macros/quote-type-variable-no-inference.check

@@ -1,18 +1,12 @@
 -- Warning: tests/neg-macros/quote-type-variable-no-inference.scala:5:17 -----------------------------------------------
-5 |    case '[ F[t, t] ] => // warn // error // error
+5 |    case '[ F[t, t] ] => // warn // error
   |                 ^
   |                 Ignored bound <: Double
   |
   |                 Consider defining bounds explicitly:
   |                   '[ type t <: Int & Double; ... ]
--- [E057] Type Mismatch Error: tests/neg-macros/quote-type-variable-no-inference.scala:5:9 -----------------------------
-5 |    case '[ F[t, t] ] => // warn // error // error
-  |         ^
-  |Type argument t does not conform to upper bound Double in subpart F[t, t] of inferred type scala.quoted.Type[F[t, t]]
-  |
-  | longer explanation available when compiling with `-explain`
 -- [E057] Type Mismatch Error: tests/neg-macros/quote-type-variable-no-inference.scala:5:15 ----------------------------
-5 |    case '[ F[t, t] ] => // warn // error // error
+5 |    case '[ F[t, t] ] => // warn // error
   |               ^
   |               Type argument t does not conform to upper bound Double
   |

tests/neg-macros/quote-type-variable-no-inference.scala

@@ -2,7 +2,7 @@ import scala.quoted.*
 
 def test(x: Type[?])(using Quotes) =
   x match
-    case '[ F[t, t] ] => // warn // error // error
+    case '[ F[t, t] ] => // warn // error
     case '[ type u <: Int & Double; F[u, u] ] =>
 
 type F[x <: Int, y <: Double]

tests/pos-macros/i18409.scala

@@ -0,0 +1,26 @@
+// scalac: -Werror -Wunused:all
+
+import scala.quoted.*
+
+object model {
+  trait Transformer[Source, Dest] {
+    def transform(from: Source): Dest
+  }
+  object Transformer {
+    trait ForProduct[A, B] extends Transformer[A, B]
+  }
+}
+
+object Ops {
+  import model.Transformer // unused import false-positive
+
+  def unapply(using Quotes)(term: quotes.reflect.Term): Option[String] = {
+    term.asExpr match {
+      case '{
+            ($transformer: Transformer.ForProduct[a, b]).transform($appliedTo)
+          } =>
+        Some("")
+      case other => None
+    }
+  }
+}