Don't look for loops in rhs of lazy vals

Author: odersky

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

@@ -71,7 +71,7 @@ class CheckLoopingImplicits extends MiniPhase:
       case SeqLiteral(elems, _) =>
         elems.foreach(checkNotLooping)
       case t: ValDef =>
-        checkNotLooping(t.rhs)
+        if !t.symbol.is(Lazy) then checkNotLooping(t.rhs)
       case _ =>
 
     if sym.isOneOf(GivenOrImplicit) then

tests/neg-custom-args/fatal-warnings/i13542.scala

@@ -32,5 +32,19 @@ val x4 =
     repIdentity(bar.toFoo)  // error
   val foo: Foo = Bar(1)
 
+val x5 =
+  implicit def barToFoo4(bar: Bar): Foo =
+    val y = bar.toFoo  // error
+    y
+  val foo: Foo = Bar(1)
+
+val x6 =
+  implicit def barToFoo4(bar: Bar): Foo =
+    lazy val y = bar.toFoo  // OK
+    if false then y else ???
+  val foo: Foo = Bar(1)
+
+
+