Fix #6188: disallow TypeApply in pattern position

Parser stability test needed to be adjusted, since we stop earlier
and emit one error less.

Author: abgruszecki

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

@@ -961,6 +961,10 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
     }
 
   def typedTypeApply(tree: untpd.TypeApply, pt: Type)(implicit ctx: Context): Tree = track("typedTypeApply") {
+    if (ctx.mode.is(Mode.Pattern)) {
+      return errorTree(tree, "invalid pattern")
+    }
+
     val isNamed = hasNamedArg(tree.args)
     val typedArgs = if (isNamed) typedNamedArgs(tree.args) else tree.args.mapconserve(typedType(_))
     record("typedTypeApply")

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

@@ -75,7 +75,11 @@ class ReTyper extends Typer with ReChecking {
   }
 
   override def typedUnApply(tree: untpd.UnApply, selType: Type)(implicit ctx: Context): UnApply = {
-    val fun1 = typedUnadapted(tree.fun, AnyFunctionProto)
+    val fun1 = {
+      // retract PatternOrTypeBits like in typedExpr
+      val ctx1 = ctx.retractMode(Mode.PatternOrTypeBits)
+      typedUnadapted(tree.fun, AnyFunctionProto)(ctx1)
+    }
     val implicits1 = tree.implicits.map(typedExpr(_))
     val patterns1 = tree.patterns.mapconserve(pat => typed(pat, pat.tpe))
     untpd.cpy.UnApply(tree)(fun1, implicits1, patterns1).withType(tree.tpe)

tests/neg/i6188.scala

@@ -0,0 +1,8 @@
+class Foo {
+  def foo[T]: Int = 9
+
+  def bar =
+    Option(9) match {
+      case Some(foo[Int]) => // error
+    }
+}

tests/neg/parser-stability-15.scala

@@ -3,5 +3,5 @@ class x0 {
 def x1 =
 x2 match          // error
 ]                 // error
-case x3[] => x0   // error // error // error
+case x3[] => x0   // error // error
 // error