Improve checks in phases

Instead of checking if we are inside of an inline method, some code
snippets need to check if we are inside of an inline trait as well

Author: timotheeandres

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

@@ -54,6 +54,9 @@ object Inlines:
   def inInlineMethod(using Context): Boolean =
     ctx.owner.ownersIterator.exists(_.isInlineMethod)
 
+  def inInlineContext(using Context): Boolean =
+    ctx.owner.ownersIterator.exists(sym => sym.isInlineMethod || sym.isInlineTrait)
+
   /** Can a call to method `meth` be inlined? */
   def isInlineable(meth: Symbol)(using Context): Boolean =
     meth.isInlineMethod && meth.hasAnnotation(defn.BodyAnnot) && !inInlineMethod
@@ -82,7 +85,7 @@ object Inlines:
       case _ =>
         isInlineable(tree.symbol) && !tree.tpe.widenTermRefExpr.isInstanceOf[MethodOrPoly] && isInlineableInCtx
 
-  private def symbolFromParent(parent: Tree)(using Context): Symbol =
+  private[dotc] def symbolFromParent(parent: Tree)(using Context): Symbol =
     if parent.symbol.isConstructor then parent.symbol.owner else parent.symbol
 
   private def inlineTraitAncestors(cls: TypeDef)(using Context): List[Tree] = cls match {

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

@@ -47,7 +47,7 @@ class Inlining extends MacroTransform, SymTransformer {
         new TreeTraverser {
           def traverse(tree: Tree)(using Context): Unit =
             tree match
-              case tree: RefTree if !Inlines.inInlineMethod && StagingLevel.level == 0 =>
+              case tree: RefTree if !Inlines.inInlineContext && StagingLevel.level == 0 =>
                 assert(!tree.symbol.isInlineMethod, tree.show)
               case _ =>
                 traverseChildren(tree)

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

@@ -84,10 +84,10 @@ class PickleQuotes extends MacroTransform {
   override def checkPostCondition(tree: Tree)(using Context): Unit =
     tree match
       case tree: Quote =>
-        assert(Inlines.inInlineMethod)
+        assert(Inlines.inInlineContext)
       case tree: Splice =>
-        assert(Inlines.inInlineMethod)
-      case _ : TypeDef if !Inlines.inInlineMethod =>
+        assert(Inlines.inInlineContext)
+      case _ : TypeDef if !Inlines.inInlineContext =>
         assert(!tree.symbol.hasAnnotation(defn.QuotedRuntime_SplicedTypeAnnot),
           s"${tree.symbol} should have been removed by PickledQuotes because it has a @quoteTypeTag")
       case _ =>

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

@@ -389,7 +389,7 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer { thisPhase
           processValOrDefDef(superAcc.wrapDefDef(tree1)(super.transform(tree1).asInstanceOf[DefDef]))
         case tree: TypeDef =>
           if tree.symbol.isInlineTrait then
-            ctx.compilationUnit.needsInlining = true
+            ctx.compilationUnit.needsInlining = true  // Transform inner classes to traits
           registerIfHasMacroAnnotations(tree)
           val sym = tree.symbol
           if (sym.isClass)
@@ -401,6 +401,8 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer { thisPhase
             tree.rhs match
               case impl: Template =>
                 for parent <- impl.parents do
+                  if Inlines.symbolFromParent(parent).isInlineTrait then
+                    ctx.compilationUnit.needsInlining = true
                   Checking.checkTraitInheritance(parent.tpe.classSymbol, sym.asClass, parent.srcPos)
                   // Constructor parameters are in scope when typing a parent.
                   // While they can safely appear in a parent tree, to preserve

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

@@ -89,8 +89,8 @@ class Splicing extends MacroTransform:
         case tree: Quote =>
           val body1 = QuoteTransformer().transform(tree.body)(using quoteContext)
           cpy.Quote(tree)(body = body1)
-        case tree: DefDef if tree.symbol.is(Inline) =>
-          // Quotes in inlined methods are only pickled after they are inlined.
+        case _: DefDef | _: TypeDef if tree.symbol.is(Inline) =>
+          // Quotes in inlined methods and traits are only pickled after they are inlined.
           tree
         case _ =>
           super.transform(tree)

tests/pos/inline-trait-1-simple-trait.scala

@@ -10,6 +10,8 @@ inline trait A:
   def f[T](x: T): Int = 2
 
   private def g = 1
+  protected[this] def p = 123
+  private[this] def pp = 123456
 
   def xx: X = "foo".asInstanceOf[X]
 end A