Fix i18628

Author: EnzeXing

compiler/src/dotty/tools/dotc/transform/init/Objects.scala

@@ -589,7 +589,7 @@ object Objects:
             values.map(ref => ref.widen(height)).join
 
           case Fun(code, thisV, klass, env) =>
-            Fun(code, thisV.widenRefOrCold(height), klass, env.widen(height))
+            Fun(code, thisV.widenRefOrCold(height), klass, env.widen(height - 1))
 
           case ref @ OfClass(klass, outer, _, args, env) =>
             val outer2 = outer.widen(height - 1)

tests/init-global/pos/i18628.scala

@@ -0,0 +1,7 @@
+object Test:
+  class Box(val x: Int)
+
+  def recur(a: => Box, b: => Box): Int =
+    a.x + recur(a, b) + b.x
+
+  recur(Box(1), Box(2))

tests/init-global/pos/i18628_2.scala

@@ -0,0 +1,7 @@
+object Test:
+  class Box(val x: Int)
+
+  def recur(a: => Box, b: Box): Int =
+    a.x + recur(a, b) + b.x
+
+  recur(Box(1), Box(2))

tests/init-global/pos/i18628_3.scala

@@ -0,0 +1,9 @@
+import scala.annotation.init.widen
+
+object Test:
+  class Box(val x: Int)
+
+  def recur(a: => Box, b: => Box): Int =
+    a.x + recur(a: @widen(5), b: @widen(5)) + b.x
+
+  recur(Box(1), Box(2))