Merge pull request #8884 from dotty-staging/fix-withSpan-on-empty-trees

Avoid setting span on empty tree after failure

Author: liufengyun

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

@@ -79,6 +79,7 @@ object Inliner {
       override def transform(t: Tree)(using Context) =
         t match {
           case Inlined(t, Nil, expr) if t.isEmpty => expr
+          case _ if t.isEmpty => t
           case _ => super.transform(t.withSpan(call.span))
         }
     }

tests/neg/inline-foreach.scala

@@ -0,0 +1,20 @@
+trait MyRange {
+  inline def foreach(inline f: Int => Unit): Unit
+}
+
+transparent inline def MyRange(inline start: Int, inline end: Int): MyRange = new {
+  inline def foreach(inline f: Int => Unit) = // error: Implementation restriction
+    var i = start
+    val e = end
+    while (i < e) {
+      f(i)
+      i += 1
+    }
+}
+
+object App {
+  val count: Int = 4
+  for (i <- MyRange(0, count)) { // error: Deferred inline method foreach in trait MyRange cannot be invoked
+    Console.println("Number: " + i)
+  }
+}