Generate static inline accessors

If a class needs inline accessors that would be added top-level
or if the accessor is to a static member, we place it in the top-level
class as a java static method.

If the accessor location in the new scheme is not the same as the
previous location, we also generate the old accessor for backward binary
compatibility but do not use it.

Fixes #13215
Fixes #15413

Author: nicolasstucki

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

@@ -2,6 +2,8 @@ package dotty.tools
 package dotc
 package inlines
 
+import scala.collection.mutable
+
 import dotty.tools.dotc.ast.{Trees, tpd, untpd}
 import Trees._
 import core._
@@ -22,6 +24,9 @@ import transform.SymUtils.*
 import config.Printers.inlining
 import util.Property
 import dotty.tools.dotc.transform.TreeMapWithStages._
+import dotty.tools.dotc.ast.desugar.packageObjectName
+import dotty.tools.dotc.core.StdNames.str
+import dotty.tools.dotc.util.{Spans, SrcPos}
 
 object PrepareInlineable {
   import tpd._
@@ -53,8 +58,8 @@ object PrepareInlineable {
     /** A tree map which inserts accessors for non-public term members accessed from inlined code.
      */
     abstract class MakeInlineableMap(val inlineSym: Symbol) extends TreeMap with Insert {
-      def accessorNameOf(name: TermName, site: Symbol)(using Context): TermName =
-        val accName = InlineAccessorName(name)
+      def accessorNameOf(name: TermName, site: Symbol, isStatic: Boolean)(using Context): TermName =
+        val accName = InlineAccessorName(if isStatic then s"static$$$name".toTermName else name)
         if site.isExtensibleClass then accName.expandedName(site) else accName
 
       /** A definition needs an accessor if it is private, protected, or qualified private
@@ -99,20 +104,32 @@ object PrepareInlineable {
      *  advantage that we can re-use the receiver as is. But it is only
      *  possible if the receiver is essentially this or an outer this, which is indicated
      *  by the test that we can find a host for the accessor.
+     *
+     *  @param inlineSym symbol of the inline method
+     *  @param compat use inline accessor format of 3.0-3.3
      */
-    class MakeInlineableDirect(inlineSym: Symbol) extends MakeInlineableMap(inlineSym) {
+    class MakeInlineableDirect(inlineSym: Symbol, compat: Boolean) extends MakeInlineableMap(inlineSym) {
       def preTransform(tree: Tree)(using Context): Tree = tree match {
         case tree: RefTree if needsAccessor(tree.symbol) =>
           if tree.symbol.isConstructor then
             report.error("Implementation restriction: cannot use private constructors in inline methods", tree.srcPos)
             tree // TODO: create a proper accessor for the private constructor
-          else
+          else if compat then
+            // Generate the accessor for backwards compatibility with 3.0-3.3
             val nearestHost = AccessProxies.hostForAccessorOf(tree.symbol)
             val host = if nearestHost.is(Package) then ctx.owner.topLevelClass else nearestHost
             useAccessor(tree, host)
+          else
+            // Generate the accessor for 3.4+
+            val nearestHost = AccessProxies.hostForAccessorOf(tree.symbol)
+            if nearestHost.is(Package) || (tree.symbol.owner.isStaticOwner && !nearestHost.isStaticOwner) then
+              useAccessor(tree, ctx.owner.topLevelClass, isStatic = true)
+            else
+              useAccessor(tree, nearestHost)
         case _ =>
           tree
       }
+
       override def ifNoHost(reference: RefTree)(using Context): Tree = reference
     }
 
@@ -228,8 +245,12 @@ object PrepareInlineable {
         // so no accessors are needed for them.
         tree
       else
+        // Generate inline accessors for 3.0-3.3
+        new MakeInlineablePassing(inlineSym).transform(
+          new MakeInlineableDirect(inlineSym, compat = true).transform(tree))
+          // Generate and use inline accessors for 3.4+
         new MakeInlineablePassing(inlineSym).transform(
-          new MakeInlineableDirect(inlineSym).transform(tree))
+          new MakeInlineableDirect(inlineSym, compat = false).transform(tree))
     }
   }
 

compiler/src/dotty/tools/dotc/quoted/Interpreter.scala

@@ -162,13 +162,17 @@ class Interpreter(pos: SrcPos, classLoader0: ClassLoader)(using Context):
   private def interpretVarargs(args: List[Object]): Object =
     args.toSeq
 
-  private def interpretedStaticMethodCall(moduleClass: Symbol, fn: Symbol, args: List[Object]): Object = {
-    val inst =
-      try loadModule(moduleClass)
+  private def interpretedStaticMethodCall(owner: Symbol, fn: Symbol, args: List[Object]): Object = {
+    val (inst, clazz) =
+      try
+        if owner.is(Module) then
+          val inst = loadModule(owner)
+          (inst, inst.getClass)
+        else
+          (null, loadClass(owner.binaryClassName))
       catch
         case MissingClassDefinedInCurrentRun(sym) =>
           suspendOnMissing(sym, pos)
-    val clazz = inst.getClass
     val name = fn.name.asTermName
     val method = getMethod(clazz, name, paramsSig(fn))
     stopIfRuntimeException(method.invoke(inst, args: _*), method)

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

@@ -67,7 +67,7 @@ abstract class AccessProxies {
     import ast.tpd._
 
     /** The name of the accessor for definition with given `name` in given `site` */
-    def accessorNameOf(name: TermName, site: Symbol)(using Context): TermName
+    def accessorNameOf(name: TermName, site: Symbol, isStatic: Boolean)(using Context): TermName
     def needsAccessor(sym: Symbol)(using Context): Boolean
 
     def ifNoHost(reference: RefTree)(using Context): Tree = {
@@ -76,20 +76,21 @@ abstract class AccessProxies {
     }
 
     /** A fresh accessor symbol */
-    private def newAccessorSymbol(owner: Symbol, name: TermName, info: Type, accessed: Symbol)(using Context): TermSymbol = {
+    private def newAccessorSymbol(owner: Symbol, name: TermName, info: Type, accessed: Symbol, isStatic: Boolean)(using Context): TermSymbol = {
       val sym = newSymbol(owner, name, Synthetic | Method, info, coord = accessed.span).entered
       if accessed.is(Private) then sym.setFlag(Final)
+      if isStatic then sym.setFlag(JavaStaticTerm)
       else if sym.allOverriddenSymbols.exists(!_.is(Deferred)) then sym.setFlag(Override)
       if accessed.hasAnnotation(defn.ExperimentalAnnot) then
         sym.addAnnotation(defn.ExperimentalAnnot)
       sym
     }
 
     /** An accessor symbol, create a fresh one unless one exists already */
-    protected def accessorSymbol(owner: Symbol, accessorName: TermName, accessorInfo: Type, accessed: Symbol)(using Context): Symbol = {
+    protected def accessorSymbol(owner: Symbol, accessorName: TermName, accessorInfo: Type, accessed: Symbol, isStatic: Boolean = false)(using Context): Symbol = {
       def refersToAccessed(sym: Symbol) = accessedBy.get(sym).contains(accessed)
       owner.info.decl(accessorName).suchThat(refersToAccessed).symbol.orElse {
-        val acc = newAccessorSymbol(owner, accessorName, accessorInfo, accessed)
+        val acc = newAccessorSymbol(owner, accessorName, accessorInfo, accessed, isStatic)
         accessedBy(acc) = accessed
         acc
       }
@@ -127,16 +128,17 @@ abstract class AccessProxies {
     /** Create an accessor unless one exists already, and replace the original
       *  access with a reference to the accessor.
       *
-      *  @param reference    The original reference to the non-public symbol
-      *  @param onLHS        The reference is on the left-hand side of an assignment
+      *  @param reference The original reference to the non-public symbol
+      *  @param accessorClass Class where the accessor will be generated
+      *  @param isStatic If this accessor will become a java static method
       */
-    def useAccessor(reference: RefTree, accessorClass: Symbol)(using Context): Tree = {
+    def useAccessor(reference: RefTree, accessorClass: Symbol, isStatic: Boolean = false)(using Context): Tree = {
       val accessed = reference.symbol.asTerm
       if (accessorClass.exists) {
-        val accessorName = accessorNameOf(accessed.name, accessorClass)
+        val accessorName = accessorNameOf(accessed.name, accessorClass, isStatic)
         val accessorInfo =
           accessed.info.ensureMethodic.asSeenFrom(accessorClass.thisType, accessed.owner)
-        val accessor = accessorSymbol(accessorClass, accessorName, accessorInfo, accessed)
+        val accessor = accessorSymbol(accessorClass, accessorName, accessorInfo, accessed, isStatic)
         rewire(reference, accessor)
       }
       else ifNoHost(reference)

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

@@ -64,7 +64,9 @@ class ProtectedAccessors extends MiniPhase {
 
   private class Accessors extends AccessProxies {
     val insert: Insert = new Insert {
-      def accessorNameOf(name: TermName, site: Symbol)(using Context): TermName = ProtectedAccessorName(name)
+      def accessorNameOf(name: TermName, site: Symbol, isStatic: Boolean)(using Context): TermName =
+        assert(!isStatic)
+        ProtectedAccessorName(name)
       def needsAccessor(sym: Symbol)(using Context) = ProtectedAccessors.needsAccessor(sym)
 
       override def ifNoHost(reference: RefTree)(using Context): Tree = {

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

@@ -35,6 +35,7 @@ import util.common._
 import util.{Property, SimpleIdentityMap, SrcPos}
 import Applications.{tupleComponentTypes, wrapDefs, defaultArgument}
 
+
 import collection.mutable
 import annotation.tailrec
 import Implicits._

compiler/test/dotty/tools/backend/jvm/DottyBytecodeTests.scala

@@ -1682,6 +1682,80 @@ class DottyBytecodeTests extends DottyBytecodeTest {
       assertSameCode(instructions, expected)
     }
   }
+
+  @Test
+  def i13215(): Unit = {
+    val code =
+      """package foo:
+        |  trait Bar:
+        |    inline def baz = Baz
+        |  private[foo] object Baz
+      """.stripMargin
+    checkBCode(code) { dir =>
+      val privateAccessors = Opcodes.ACC_PRIVATE | Opcodes.ACC_PROTECTED
+      val barClass = loadClassNode(dir.subdirectoryNamed("foo").lookupName("Bar.class", directory = false).input, skipDebugInfo = false)
+
+      // For 3.0-3.3 compat
+      val accessorOld  = getMethod(barClass, "foo$Bar$$inline$Baz")
+      assert(accessorOld.signature == "()Lfoo/Baz$;", accessorOld.signature)
+      assert((accessorOld.access & privateAccessors) == 0)
+
+      // For 3.4+
+      val accessorNew  = getMethod(barClass, "foo$Bar$$inline$static$Baz") // FIXME  "foo$$inline$static$Baz"?
+      assert(accessorNew.signature == "()Lfoo/Baz$;", accessorNew.signature)
+      assert((accessorNew.access & privateAccessors) == 0)
+    }
+  }
+
+  @Test
+  def i15413(): Unit = {
+    val code =
+      """import scala.quoted.*
+        |class Macro:
+        |  inline def foo = Macro.fooImpl
+        |object Macro:
+        |  private def fooImpl = {}
+      """.stripMargin
+    checkBCode(code) { dir =>
+      val privateAccessors = Opcodes.ACC_PRIVATE | Opcodes.ACC_PROTECTED
+      val macroClass = loadClassNode(dir.lookupName("Macro.class", directory = false).input, skipDebugInfo = false)
+
+      // For 3.0-3.3 compat
+      val accessorOld  = getMethod(macroClass, "Macro$$inline$fooImpl")
+      assert(accessorOld.signature == "()V")
+      assert((accessorOld.access & privateAccessors) == 0)
+
+      // For 3.4+
+      val accessorNew  = getMethod(macroClass, "Macro$$inline$static$fooImpl")
+      assert(accessorNew.signature == "()V")
+      assert((accessorNew.access & privateAccessors) == 0)
+    }
+  }
+
+  @Test
+  def i15413b(): Unit = {
+    val code =
+      """package foo
+        |class C:
+        |  inline def baz = D.bazImpl
+        |object D:
+        |  private[foo] def bazImpl = {}
+      """.stripMargin
+    checkBCode(code) { dir =>
+      val privateAccessors = Opcodes.ACC_PRIVATE | Opcodes.ACC_PROTECTED
+      val barClass = loadClassNode(dir.subdirectoryNamed("foo").lookupName("C.class", directory = false).input, skipDebugInfo = false)
+
+      // For 3.0-3.3 compat
+      val accessorOld  = getMethod(barClass, "inline$bazImpl$i1")
+      assert(accessorOld.desc == "(Lfoo/D$;)V", accessorOld.desc)
+      assert((accessorOld.access & privateAccessors) == 0)
+
+      // For 3.4+
+      val accessorNew  = getMethod(barClass, "foo$C$$inline$static$bazImpl") // FIXME "foo$D$$inline$static$bazImpl"?
+      assert(accessorNew.signature == "()V", accessorNew.signature)
+      assert((accessorNew.access & privateAccessors) == 0)
+    }
+  }
 }
 
 object invocationReceiversTestCode {

tests/pos-macros/i15413/Macro_1.scala

@@ -0,0 +1,7 @@
+import scala.quoted.*
+
+class Macro:
+  inline def foo = ${ Macro.fooImpl }
+
+object Macro:
+  private def fooImpl(using Quotes) = '{}

tests/pos-macros/i15413/Test_2.scala

@@ -0,0 +1,2 @@
+def test =
+  new Macro().foo

tests/pos-macros/i15413b/Macro_1.scala

@@ -0,0 +1,5 @@
+import scala.quoted.*
+
+inline def foo = ${ fooImpl }
+
+private def fooImpl(using Quotes) = '{}

tests/pos-macros/i15413b/Test_2.scala

@@ -0,0 +1 @@
+def test = foo

tests/pos-macros/i15413c/Macro.scala

@@ -0,0 +1,7 @@
+import scala.quoted.*
+
+class Macro:
+  inline def foo = ${ Macro.fooImpl }
+
+object Macro:
+  private def fooImpl(using Quotes) = '{}

tests/pos-macros/i15413c/Test.scala

@@ -0,0 +1,2 @@
+def test =
+  new Macro().foo

tests/pos-macros/i15413d/Macro.scala

@@ -0,0 +1,5 @@
+import scala.quoted.*
+
+inline def foo = ${ fooImpl }
+
+private def fooImpl(using Quotes) = '{}

tests/pos-macros/i15413d/Test.scala

@@ -0,0 +1 @@
+def test = foo

tests/pos-macros/i15413e/Macro_1.scala

@@ -0,0 +1,18 @@
+package myMacro
+
+import scala.quoted.*
+
+class Macro:
+  inline def foo = ${ Foo.impl }
+  inline def bar = ${ Bar.impl }
+  inline def baz = ${ foo.Foo.impl }
+
+object Foo:
+  private[myMacro] def impl(using Quotes) = '{}
+
+object Bar:
+  private[myMacro] def impl(using Quotes) = '{1}
+
+package foo:
+  object Foo:
+    private[myMacro] def impl(using Quotes) = '{"abc"}

tests/pos-macros/i15413e/Test_2.scala

@@ -0,0 +1,6 @@
+import myMacro.Macro
+
+def test(m: Macro) =
+  m.foo
+  m.bar
+  m.baz

tests/run-macros/i13215-compat-3.1/A_1_c3.1.0.scala

@@ -0,0 +1,6 @@
+package foo
+
+trait Bar:
+  inline def baz = Baz
+
+private[foo] object Baz

tests/run-macros/i13215-compat-3.1/A_3.scala

@@ -0,0 +1,6 @@
+package foo
+
+trait Bar:
+  inline def baz = Baz
+
+private[foo] object Baz

tests/run-macros/i13215-compat-3.1/B_2.scala

@@ -0,0 +1,25 @@
+// We first compile A using 3.1 to generate the old accessors
+// Then we compile this file to link against the old accessors
+// Finally we recompile A using the current compiler to generate a version
+// of A that contains the new accessors (and the old for backwards compat)
+
+@main def Test =
+  val bar: foo.Bar = new foo.Bar{}
+  bar.baz // test that old accessor links in 3.4+
+
+  // Check that both accessors exist in the bytecode
+  val inlineAccessors =
+    java.lang.Class.forName("foo.Bar").getMethods()
+      .filter(_.getName().contains("inline"))
+      .filter(x => (x.getModifiers() & java.lang.reflect.Modifier.STATIC) == 0)
+      .map(_.getName())
+      .toList
+  val staticInlineAccessors =
+    java.lang.Class.forName("foo.Bar").getMethods()
+      .filter(_.getName().contains("inline"))
+      .filter(x => (x.getModifiers() & java.lang.reflect.Modifier.STATIC) != 0)
+      .map(_.getName())
+      .toList
+
+  println("3.0-3.3 inline accessor: " + inlineAccessors)
+  println("3.4+ inline accessor: " + staticInlineAccessors)

tests/run-macros/i15413-compat-3.1.check

@@ -0,0 +1,2 @@
+3.0-3.3 inline accessor: List(Macro$$inline$fooImpl)
+3.4+ inline accessor: List(Macro$$inline$static$fooImpl)

tests/run-macros/i15413-compat-3.1/Macro_1_c3.1.0.scala

@@ -0,0 +1,7 @@
+import scala.quoted.*
+
+class Macro:
+  inline def foo = /*${*/ Macro.fooImpl /*}*/
+
+object Macro:
+  private def fooImpl/*(using Quotes)*/ = {}

tests/run-macros/i15413-compat-3.1/Macro_3.scala

@@ -0,0 +1,7 @@
+import scala.quoted.*
+
+class Macro:
+  inline def foo = /*${*/ Macro.fooImpl /*}*/
+
+object Macro:
+  private def fooImpl/*(using Quotes)*/ = {}