Improve ref check of constructors

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

@@ -13,6 +13,7 @@ import Decorators.*
 import Denotations.*, SymDenotations.*
 import DenotTransformers.*
 import NullOpsDecorator.*
+import util.Spans.Span
 
 object ElimRepeated {
   val name: String = "elimRepeated"
@@ -183,15 +184,16 @@ class ElimRepeated extends MiniPhase with InfoTransformer { thisPhase =>
         .get
         .symbol.asTerm
       // Generate the method
-      val forwarderDef = DefDef(forwarderSym, prefss => {
+      val forwarderDef = DefDef(forwarderSym, prefss =>
         val init :+ (last :+ vararg) = prefss: @unchecked
         // Can't call `.argTypes` here because the underlying array type is of the
         // form `Array[? <: SomeType]`, so we need `.argInfos` to get the `TypeBounds`.
         val elemtp = vararg.tpe.widen.argInfos.head
         ref(sym.termRef)
           .appliedToArgss(init)
           .appliedToTermArgs(last :+ wrapArray(vararg, elemtp))
-        })
+          .withSpan(Span(tree.span.start))
+      ).withSpan(tree.span.toSynthetic)
       Thicket(tree, forwarderDef)
     else
       tree

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

@@ -122,7 +122,8 @@ class ForwardDepChecks extends MiniPhase:
   override def transformApply(tree: Apply)(using Context): Apply =
     if (isSelfConstrCall(tree))
       assert(ctx.owner.isConstructor)
-      checkSelfConstructorCall()
+      if currentLevel.isInstanceOf[LevelInfo] then // ElimRepeated can introduce RHS of ctor which is not a block
+        checkSelfConstructorCall()
     tree
 
   override def transformNew(tree: New)(using Context): New = {

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

@@ -3115,10 +3115,15 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
         def checkThisConstrCall(tree: Tree): Unit = tree match
           case app: Apply if untpd.isSelfConstrCall(app) =>
             if !sym.is(Synthetic)
-              && sym.span.exists && app.symbol.span.exists && sym.span.start <= app.symbol.span.start
+              && sym.span.exists
+              && app.symbol.span.exists
+              && sym.span.start <= app.symbol.span.start
+              && tree.span.exists && !tree.span.isSynthetic
             then
               report.error("secondary constructor must call a preceding constructor", app.srcPos)
-          case Block(call :: _, _) => checkThisConstrCall(call)
+          case Block(call :: _, expr) =>
+            checkThisConstrCall(call)
+            checkThisConstrCall(expr)
           case _ =>
 
         checkThisConstrCall(rhs1)

tests/neg/i24249.scala

@@ -0,0 +1,9 @@
+
+
+class C(i: Int) {
+  def this(s: String) = this(j = s.toInt, i = 27) // error
+
+  def this(i: Int, j: Int) = this(i + j)
+
+  def c = 42 * i
+}

tests/pos/i24249.scala

@@ -0,0 +1,5 @@
+
+import annotation.*
+
+class Foo:
+  @varargs def this(x: Int*) = this()