Merge pull request #277 from scala/backport-lts-3.3-22655

Backport "Fix opaque types leaking rhs when inlined and found in type params (and a related stale symbol issue)" to 3.3 LTS

Author: tgodzik

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

@@ -399,7 +399,17 @@ class Inliner(val call: tpd.Tree)(using Context):
    *  type aliases, add proxy definitions to `opaqueProxies` that expose these aliases.
    */
   private def addOpaqueProxies(tp: Type, span: Span, forThisProxy: Boolean)(using Context): Unit =
-    tp.foreachPart {
+    val foreachTpPart =
+      (p: Type => Unit) =>
+        if forThisProxy then
+          // Performs operations on all parts of this type, outside of the applied type arguments
+          new ForeachAccumulator(p, StopAt.None) {
+            override def apply(x: Unit, tp: Type) = tp match
+              case AppliedType(tycon, _) => super.apply(x, tycon)
+              case other => super.apply(x, other)
+          }.apply((), tp)
+        else tp.foreachPart(p)
+    foreachTpPart {
       case ref: TermRef =>
         for cls <- ref.widen.baseClasses do
           if cls.containsOpaques

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

@@ -694,7 +694,13 @@ class Namer { typer: Typer =>
               enterSymbol(classConstructorCompanion(classSym.asClass))
             else
               for moduleSym <- companionVals do
-                if moduleSym.is(Module) && !moduleSym.isDefinedInCurrentRun then
+                // by not going through `.lastKnownDenotation` (instead using `.current`),
+                // we guarantee that the `moduleSym` will be brought forward to the current run,
+                // rendering `moduleSym.isDefinedInCurrentRun` as always true.
+                // We want to regenerate the companion instead of bringing it forward,
+                // as even if we are able to bring forward the object symbol,
+                // we might not be able to do the same with its stale module class symbol (see `tests/pos/i20449`)
+                if moduleSym.lastKnownDenotation.is(Module) && !moduleSym.isDefinedInCurrentRun then
                   val companion =
                     if needsConstructorProxies(classSym) then
                       classConstructorCompanion(classSym.asClass)

tests/pos-macros/i20449/Macro.scala

@@ -0,0 +1,3 @@
+import scala.quoted.*
+transparent inline def getTypeInfo[T]() = ${ getTypeInfoImpl[T] }
+def getTypeInfoImpl[T: Type](using ctx: Quotes): Expr[Unit] = '{ () }

tests/pos-macros/i20449/Main.scala

@@ -0,0 +1,6 @@
+
+class Wrapper1[A]
+val a = {
+  getTypeInfo[Any]()
+  val wrapper2 = Wrapper1[Any]()
+}

tests/run-macros/i20449.check

@@ -0,0 +1,50 @@
+------ UserName.T - Directly -------
+Original: Main_2$package.UserName.T
+Dealias: Main_2$package.UserName.T
+Dealias dealias: Main_2$package.UserName.T
+    
+------ UserName.T - Directly -------
+Original: Main_2$package.UserName
+Dealias: Main_2$package.UserName.T
+Dealias dealias: Main_2$package.UserName.T
+    
+------ ForeignWrapper1[UserName.T] -------
+Original: Main_2$package.UserName.T
+Dealias: Main_2$package.UserName.T
+Dealias dealias: Main_2$package.UserName.T
+    
+------ ForeignWrapper2[UserName.T] -------
+Original: Main_2$package.UserName.T
+Dealias: Main_2$package.UserName.T
+Dealias dealias: Main_2$package.UserName.T
+    
+------ ForeignWrapper1[UserName] -------
+Original: Main_2$package.UserName
+Dealias: Main_2$package.UserName.T
+Dealias dealias: Main_2$package.UserName.T
+    
+------ ForeignWrapper2[UserName] -------
+Original: Main_2$package.UserName
+Dealias: Main_2$package.UserName.T
+Dealias dealias: Main_2$package.UserName.T
+    
+------ Wrapper1[UserName.T] -------
+Original: Main_2$package.UserName.T
+Dealias: Main_2$package.UserName.T
+Dealias dealias: Main_2$package.UserName.T
+    
+------ Wrapper2[UserName.T] -------
+Original: Main_2$package.UserName.T
+Dealias: Main_2$package.UserName.T
+Dealias dealias: Main_2$package.UserName.T
+    
+------ Wrapper1[UserName] -------
+Original: Main_2$package.UserName
+Dealias: Main_2$package.UserName.T
+Dealias dealias: Main_2$package.UserName.T
+    
+------ Wrapper2[UserName] -------
+Original: Main_2$package.UserName
+Dealias: Main_2$package.UserName.T
+Dealias dealias: Main_2$package.UserName.T
+    

tests/run-macros/i20449/Macro_1.scala

@@ -0,0 +1,29 @@
+import scala.quoted.*
+
+class ForeignWrapper1[-A] {
+  inline def getTypeInfo(inline source: String): String =
+    ${ getTypeInfoImpl[A]('source) }
+  def createWrapper2 = ForeignWrapper2(this)
+}
+
+class ForeignWrapper2[-A](val self: ForeignWrapper1[A]) {
+  inline def getTypeInfo(inline source: String): String =
+    ${getTypeInfoImpl[A]('source)}
+}
+
+transparent inline def getTypeInfo[T](inline source: String) =
+  ${ getTypeInfoImpl[T]('source) }
+
+def getTypeInfoImpl[T: Type](source: Expr[String])(using ctx: Quotes) : Expr[String] = {
+  import ctx.reflect.*
+
+  val tpe = TypeRepr.of[T]
+  val str =
+    s"""|------ ${source.valueOrAbort} -------
+       |Original: ${tpe.show}
+       |Dealias: ${tpe.dealias.show}
+       |Dealias dealias: ${tpe.dealias.dealias.show}
+    """.stripMargin
+
+  Expr(str)
+}

tests/run-macros/i20449/Main_2.scala

@@ -0,0 +1,41 @@
+object UserName {
+  opaque type T = String
+
+  def apply(s: String): T = s
+}
+
+type UserName = UserName.T
+
+class Wrapper1[-A] {
+  inline def getTypeInfo(inline source: String): String =
+    ${ getTypeInfoImpl[A]('source) }
+  def createWrapper2 = Wrapper2(this)
+}
+
+class Wrapper2[-A](val self: Wrapper1[A]) {
+  inline def getTypeInfo(inline source: String): String =
+    ${getTypeInfoImpl[A]('source)}
+}
+
+
+@main def Test() = {
+  println(getTypeInfo[UserName.T]("UserName.T - Directly"))
+  println(getTypeInfo[UserName]("UserName.T - Directly"))
+
+  val foreignWrapper = ForeignWrapper1[UserName.T]()
+  println(foreignWrapper.getTypeInfo("ForeignWrapper1[UserName.T]"))
+  println(foreignWrapper.createWrapper2.getTypeInfo("ForeignWrapper2[UserName.T]"))
+
+  val foreignWrapper2 = ForeignWrapper1[UserName]()
+  println(foreignWrapper2.getTypeInfo("ForeignWrapper1[UserName]"))
+  println(foreignWrapper2.createWrapper2.getTypeInfo("ForeignWrapper2[UserName]"))
+
+  val wrapper = Wrapper1[UserName.T]()
+  println(wrapper.getTypeInfo("Wrapper1[UserName.T]"))
+  println(wrapper.createWrapper2.getTypeInfo("Wrapper2[UserName.T]"))
+
+  val wrapper2 = Wrapper1[UserName]()
+  println(wrapper2.getTypeInfo("Wrapper1[UserName]"))
+  println(wrapper2.createWrapper2.getTypeInfo("Wrapper2[UserName]"))
+
+}