Add Eq check for Apply tree in adapting patterns

Author: liufengyun

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

@@ -2437,7 +2437,7 @@ class Typer extends Namer with TypeAssigner with Applications with Implicits wit
     */
   protected def checkEqualityEvidence(tree: tpd.Tree, pt: Type)(implicit ctx: Context) : Unit = {
     tree match {
-      case _: RefTree | _: Literal
+      case _: RefTree | _: Literal | _: Apply
         if !isVarPattern(tree) &&
           !(tree.tpe <:< pt) (ctx.addMode(Mode.GADTflexible)) =>
         val cmp =

tests/neg/i1846.scala

@@ -0,0 +1,18 @@
+object Test {
+  def main(args: Array[String]): Unit = {
+    val x = 42
+    val Y = "h"
+
+    x match { case { 42 } => 42 }                      // ok
+    x match { case { 42.toString } => 42 }             // error
+    x match { case { 42 }.toString => 42 }             // error
+    x match { case { "h" }.toString => println(42) }   // error
+    x match { case { "h".toString } => println(42) }   // error
+    x match { case Y => println(42) }                  // error
+    x match { case Y.toString => println(42) }         // error
+
+    Y match { case Y.toString => println(42) }         // ok
+    Y match { case { Y.toString } => println(42) }     // ok
+    Y match { case { Y }.toString => println(42) }     // ok
+  }
+}