Backport "Fix "Compiler crash when calling another file's inline def that uses a private constructor"" to 3.8.2 (#25189)

Backports #24941 to the 3.8.2-RC2.

PR submitted by the release tooling.
[skip ci]

Author: WojciechMazur

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

@@ -85,7 +85,11 @@ class ExpandPrivate extends MiniPhase with IdentityDenotTransformer { thisPhase
         (j < 0 || p2(j) == separatorChar)
       }
 
-      assert(d.symbol.source.exists &&
+      // Skip assertion for @publicInBinary members - they are designed to be accessed
+      // across compilation units (e.g., when inlined). See SIP-52.
+      val isPublicInBinary = d.hasPublicInBinary
+      assert(isPublicInBinary ||
+             d.symbol.source.exists &&
              ctx.owner.source.exists &&
              isSimilar(d.symbol.source.path, ctx.owner.source.path),
           s"private ${d.symbol.showLocated} in ${d.symbol.source} accessed from ${ctx.owner.showLocated} in ${ctx.owner.source}")

tests/pos/i24869/Demo_2.scala

@@ -0,0 +1,42 @@
+package demo
+
+object Demo extends Utils {
+  // Test case 1: Basic case class with @publicInBinary private constructor
+  val test1 = TestClass(???)
+
+  // Test case 2: Regular class with @publicInBinary private constructor
+  val test2 = RegularClass.create(42)
+
+  // Test case 3: Nested class with @publicInBinary private constructor
+  val outer = new Outer
+  val test3 = outer.Inner.make("hello")
+
+  // Test case 4: @publicInBinary on private[Scope] method
+  val wpm = new WithPrivateMethod
+  val test4 = WithPrivateMethod.callSecret(wpm, 21)
+
+  // Test case 5: @publicInBinary on private val accessor (via constructor)
+  val test5a = WithPrivateVal.create("secret")
+  val test5b = WithPrivateVal.getHidden(test5a)
+
+  // Test case 6: Multiple @publicInBinary constructors
+  val test6a = MultiConstructor.make1(100)
+  val test6b = MultiConstructor.make2(200, "custom")
+
+  // Test case 7: Case class with @publicInBinary and parameters
+  val test7 = DataClass.make("test", 123)
+
+  // Test case 8: @publicInBinary on private[Scope] val
+  val wpvs = new WithPrivateValScoped
+  val test8 = WithPrivateValScoped.getSecret(wpvs)
+
+  // Test case 9: @publicInBinary on private[Scope] lazy val
+  val wlv = new WithLazyVal
+  val test9 = WithLazyVal.getComputed(wlv)
+
+  // Test case 10: Top-level class with @publicInBinary
+  val test10 = TopLevelPublicInBinary.create(3.14)
+
+  // Test case 11: Trait with companion having @publicInBinary class
+  val test11: Describable = DescribableImpl.create("description")
+}

tests/pos/i24869/Utils_1.scala

@@ -0,0 +1,101 @@
+package demo
+
+import scala.annotation.publicInBinary
+
+class Utils {
+  // Test case 1: Basic case class with @publicInBinary private constructor
+  final case class TestClass @publicInBinary private () {}
+
+  object TestClass {
+    inline def apply(inline clips: List[String]): TestClass = new TestClass()
+  }
+
+  // Test case 2: Regular class with @publicInBinary private constructor
+  class RegularClass @publicInBinary private (val x: Int) {
+    def this() = this(0)
+  }
+
+  object RegularClass {
+    inline def create(inline value: Int): RegularClass = new RegularClass(value)
+  }
+
+  // Test case 3: Nested class with @publicInBinary private constructor
+  class Outer {
+    class Inner @publicInBinary private (val name: String)
+    object Inner {
+      inline def make(inline n: String): Inner = new Inner(n)
+    }
+  }
+
+  // Test case 4: @publicInBinary on private[Scope] method (not constructor)
+  class WithPrivateMethod {
+    @publicInBinary private[WithPrivateMethod] def secretMethod(x: Int): Int = x * 2
+  }
+
+  object WithPrivateMethod {
+    inline def callSecret(w: WithPrivateMethod, inline x: Int): Int = w.secretMethod(x)
+  }
+
+  // Test case 5: @publicInBinary on private val accessor (via constructor)
+  class WithPrivateVal @publicInBinary private (val hidden: String)
+
+  object WithPrivateVal {
+    inline def getHidden(w: WithPrivateVal): String = w.hidden
+    inline def create(inline s: String): WithPrivateVal = new WithPrivateVal(s)
+  }
+
+  // Test case 6: Multiple @publicInBinary constructors with different arities
+  class MultiConstructor @publicInBinary private (val a: Int, val b: String) {
+    @publicInBinary private def this(a: Int) = this(a, "default")
+  }
+
+  object MultiConstructor {
+    inline def make1(inline x: Int): MultiConstructor = new MultiConstructor(x)
+    inline def make2(inline x: Int, inline y: String): MultiConstructor = new MultiConstructor(x, y)
+  }
+
+  // Test case 7: Case class with @publicInBinary and parameters
+  final case class DataClass @publicInBinary private (name: String, value: Int)
+
+  object DataClass {
+    inline def make(inline n: String, inline v: Int): DataClass = new DataClass(n, v)
+  }
+
+  // Test case 8: @publicInBinary on private[Scope] val
+  class WithPrivateValScoped {
+    @publicInBinary private[WithPrivateValScoped] val secretVal: Int = 42
+  }
+
+  object WithPrivateValScoped {
+    inline def getSecret(w: WithPrivateValScoped): Int = w.secretVal
+  }
+
+  // Test case 9: @publicInBinary on private[Scope] lazy val
+  class WithLazyVal {
+    @publicInBinary private[WithLazyVal] lazy val computed: String = "computed"
+  }
+
+  object WithLazyVal {
+    inline def getComputed(w: WithLazyVal): String = w.computed
+  }
+}
+
+// Test case 10: Top-level class with @publicInBinary (not nested in Utils)
+class TopLevelPublicInBinary @publicInBinary private (val value: Double)
+
+object TopLevelPublicInBinary {
+  inline def create(inline v: Double): TopLevelPublicInBinary = new TopLevelPublicInBinary(v)
+}
+
+// Test case 11: Trait with companion having @publicInBinary class
+trait Describable {
+  def describe: String
+}
+
+class DescribableImpl @publicInBinary private (val desc: String) extends Describable {
+  def describe: String = desc
+}
+
+object DescribableImpl {
+  inline def create(inline d: String): Describable = new DescribableImpl(d)
+}