Refactor level checking / type healing logic

nicolasstucki · nicolasstucki · commit f092f78fa08c · 2023-03-10T17:32:33.000+01:00
Disentangle level checking from type healing.
diff --git a/compiler/src/dotty/tools/dotc/transform/PCPCheckAndHeal.scala b/compiler/src/dotty/tools/dotc/transform/PCPCheckAndHeal.scala
@@ -61,24 +61,26 @@ class PCPCheckAndHeal(@constructorOnly ictx: Context) extends TreeMapWithStages(
       super.transform(tree)
     else tree match {
 
-      case _: TypeTree | _: RefTree if tree.isType  =>
+      case _: TypeTree | _: RefTree if tree.isType =>
         val healedType = healType(tree.srcPos)(tree.tpe)
         if healedType == tree.tpe then tree
         else TypeTree(healedType).withSpan(tree.span)
+      case tree: Ident if isWildcardArg(tree) =>
+        tree.withType(healType(tree.srcPos)(tree.tpe))
+      case tree: Ident => // this is a term Ident
+        checkLevelConsistency(tree)
+        tree
+      case tree: This =>
+        checkLevelConsistency(tree)
+        tree
       case _: AppliedTypeTree =>
         super.transform(tree) match
           case tree1: AppliedTypeTree if tree1 ne tree =>
             // propagate healed types
             tree1.withType(tree1.tpt.tpe.appliedTo(tree1.args.map(_.tpe)))
           case tree1 => tree1
-
-      case _: Ident | _: This =>
-        tree.withType(healTypeOfTerm(tree.srcPos)(tree.tpe))
-
-      // Remove inline defs in quoted code. Already fully inlined.
       case tree: DefDef if tree.symbol.is(Inline) && level > 0 =>
-        EmptyTree
-
+        EmptyTree // Remove inline defs in quoted code. Already fully inlined.
       case tree: ValOrDefDef =>
         checkAnnotations(tree)
         healInfo(tree, tree.tpt.srcPos)
@@ -88,7 +90,7 @@ class PCPCheckAndHeal(@constructorOnly ictx: Context) extends TreeMapWithStages(
         healInfo(tree, tree.srcPos)
         super.transform(tree)
       case tree: UnApply =>
-        super.transform(tree).withType(healTypeOfTerm(tree.srcPos)(tree.tpe))
+        super.transform(tree).withType(healType(tree.srcPos)(tree.tpe))
       case tree: TypeDef if tree.symbol.is(Case) && level > 0 =>
         report.error(reporting.CaseClassInInlinedCode(tree), tree)
         super.transform(tree)
@@ -115,7 +117,7 @@ class PCPCheckAndHeal(@constructorOnly ictx: Context) extends TreeMapWithStages(
     if body.isTerm then
       // `quoted.runtime.Expr.quote[T](<body>)`  --> `quoted.runtime.Expr.quote[T2](<body2>)`
       val TypeApply(fun, targs) = quote.fun: @unchecked
-      val targs2 = targs.map(targ => TypeTree(healTypeOfTerm(quote.fun.srcPos)(targ.tpe)))
+      val targs2 = targs.map(targ => TypeTree(healType(quote.fun.srcPos)(targ.tpe)))
       cpy.Apply(quote)(cpy.TypeApply(quote.fun)(fun, targs2), body2 :: Nil)
     else
       val quotes = quote.args.mapConserve(transform)
@@ -190,61 +192,57 @@ class PCPCheckAndHeal(@constructorOnly ictx: Context) extends TreeMapWithStages(
     def apply(tp: Type): Type =
       tp match
         case tp: TypeRef =>
-          tp.prefix match
-            case NoPrefix if level > levelOf(tp.symbol) && !tp.typeSymbol.hasAnnotation(defn.QuotedRuntime_SplicedTypeAnnot) =>
-              tryHealTypeOfType(tp.symbol, tp, pos)
-            case prefix: ThisType if !tp.symbol.isStatic && level > levelOf(prefix.cls) =>
-              tryHealTypeOfType(tp.symbol, tp, pos)
-            case prefix: TermRef if tp.symbol.isTypeSplice =>
-              prefix.symbol.info.argInfos match
-                case (tb: TypeBounds) :: _ =>
-                  report.error(em"Cannot splice $tp because it is a wildcard type", pos)
-                case _ =>
-              // Heal explicit type splice in the code
-              if level > 0 then getQuoteTypeTags.getTagRef(prefix) else tp
-            case prefix: TermRef if !prefix.symbol.isStatic && level > levelOf(prefix.symbol) =>
-              tryHealTypeOfType(prefix.symbol, tp, pos)
-            case _ =>
-              mapOver(tp)
+          healTypeRef(tp)
         case tp @ TermRef(NoPrefix, _) if !tp.symbol.isStatic && level > levelOf(tp.symbol) =>
           levelError(tp.symbol, tp, pos)
-        case tp: ThisType if level != -1 && level != levelOf(tp.cls) =>
-          levelError(tp.cls, tp, pos)
         case tp: AnnotatedType =>
           val newAnnotTree = transform(tp.annot.tree)
           derivedAnnotatedType(tp, apply(tp.parent), tp.annot.derivedAnnotation(newAnnotTree))
         case _ =>
           mapOver(tp)
 
-    /** Try to dealias or heal reference to type `T` used in a higher level than its definition.
-     *  Returns a reference to a type tag generated by `QuoteTypeTags` that contains a
-     *  reference to a type alias containing the equivalent of `${summon[quoted.Type[T]]}`.
-     *  Emits and error if `T` cannot be healed and returns `T`.
-     */
-    private def tryHealTypeOfType(sym: Symbol, tp: TypeRef, pos: SrcPos)(using Context): Type = {
+    private def healTypeRef(tp: TypeRef): Type =
+      tp.prefix match
+        case prefix: TermRef if tp.symbol.isTypeSplice =>
+          checkNotWildcardSplice(tp)
+          if level == 0 then tp else getQuoteTypeTags.getTagRef(prefix)
+        case prefix: TermRef if !prefix.symbol.isStatic && level > levelOf(prefix.symbol) =>
+          dealiasAndTryHeal(prefix.symbol, tp, pos)
+        case NoPrefix if level > levelOf(tp.symbol) && !tp.typeSymbol.hasAnnotation(defn.QuotedRuntime_SplicedTypeAnnot) =>
+          dealiasAndTryHeal(tp.symbol, tp, pos)
+        case prefix: ThisType if level > levelOf(prefix.cls) && !tp.symbol.isStatic =>
+          dealiasAndTryHeal(tp.symbol, tp, pos)
+        case _ =>
+          mapOver(tp)
+
+    private def dealiasAndTryHeal(sym: Symbol, tp: TypeRef, pos: SrcPos)(using Context): Type =
       val tp1 = tp.dealias
       if tp1 != tp then apply(tp1)
       else tryHeal(tp.symbol, tp, pos)
-    }
-  }
 
-  /** Check phase consistency of terms and heal inconsistent type references. */
-  private def healTypeOfTerm(pos: SrcPos)(using Context) = new TypeMap {
-    def apply(tp: Type): Type =
-      tp match
-        case tp @ TypeRef(NoPrefix, _) if level > levelOf(tp.symbol) =>
-          tryHeal(tp.symbol, tp, pos)
-        case tp @ TermRef(NoPrefix, _) if !tp.symbol.isStatic && level != levelOf(tp.symbol) =>
-          levelError(tp.symbol, tp, pos)
-        case tp: ThisType if level != -1 && level != levelOf(tp.cls) =>
-          levelError(tp.cls, tp, pos)
-        case tp: AnnotatedType =>
-          derivedAnnotatedType(tp, apply(tp.parent), tp.annot)
+    private def checkNotWildcardSplice(splice: TypeRef)(using Context): Unit =
+      splice.prefix.termSymbol.info.argInfos match
+        case (tb: TypeBounds) :: _ => report.error(em"Cannot splice $splice because it is a wildcard type", pos)
         case _ =>
-          if tp.typeSymbol.is(Package) then tp
-          else mapOver(tp)
   }
 
+  /** Check level consistency of terms references */
+  private def checkLevelConsistency(tree: Ident | This)(using Context): Unit =
+    new TypeTraverser {
+      def traverse(tp: Type): Unit =
+        tp match
+          case tp @ TermRef(NoPrefix, _) if !tp.symbol.isStatic && level != levelOf(tp.symbol) =>
+            levelError(tp.symbol, tp, tree.srcPos)
+          case tp: ThisType if level != -1 && level != levelOf(tp.cls) =>
+            levelError(tp.cls, tp, tree.srcPos)
+          case tp: AnnotatedType =>
+            traverse(tp.parent)
+          case _ if tp.typeSymbol.is(Package) =>
+            // OK
+          case _ =>
+             traverseChildren(tp)
+    }.traverse(tree.tpe)
+
   /** Try to heal reference to type `T` used in a higher level than its definition.
    *  Returns a reference to a type tag generated by `QuoteTypeTags` that contains a
    *  reference to a type alias containing the equivalent of `${summon[quoted.Type[T]]}`.
diff --git a/compiler/src/dotty/tools/dotc/transform/TreeChecker.scala b/compiler/src/dotty/tools/dotc/transform/TreeChecker.scala
@@ -678,7 +678,7 @@ object TreeChecker {
         defn.FunctionOf(List(defn.QuotesClass.typeRef), expectedResultType, isContextual = true)
       val expectedContentType =
         defn.FunctionOf(argQuotedTypes, contextualResult)
-      assert(content.typeOpt =:= expectedContentType)
+      assert(content.typeOpt =:= expectedContentType, i"expected content of the hole to be ${expectedContentType} but got ${content.typeOpt}")
 
       tree1
     }
diff --git a/tests/pos-macros/i7519b.scala b/tests/pos-macros/i7519b.scala
@@ -9,5 +9,5 @@ inline def quote[T]: Quoted[T] = ${ quoteImpl[T] }
 
 def quoteImpl[T: Type](using Quotes): Expr[Quoted[T]] = {
   val value: Expr[Int] = '{ 42 }
-  '{ new Quoted[T @Annot($value)] }
+  '{ new Quoted[T @Annot($value)]: Quoted[T] } // ascription is added to ensure that the splice of the annotation does not leak outside of the quote
 }

Original file line number	Diff line number	Diff line change
`@@ -678,7 +678,7 @@ object TreeChecker {`
`678`	`678`	`defn.FunctionOf(List(defn.QuotesClass.typeRef), expectedResultType, isContextual = true)`
`679`	`679`	`val expectedContentType =`
`680`	`680`	`defn.FunctionOf(argQuotedTypes, contextualResult)`
`681`		`- assert(content.typeOpt =:= expectedContentType)`
	`681`	`+ assert(content.typeOpt =:= expectedContentType, i"expected content of the hole to be ${expectedContentType} but got ${content.typeOpt}")`
`682`	`682`
`683`	`683`	`tree1`
`684`	`684`	`}`
Original file line number	Diff line number	Diff line change
`@@ -9,5 +9,5 @@ inline def quote[T]: Quoted[T] = ${ quoteImpl[T] }`
`9`	`9`
`10`	`10`	`def quoteImpl[T: Type](using Quotes): Expr[Quoted[T]] = {`
`11`	`11`	`val value: Expr[Int] = '{ 42 }`
`12`		`- '{ new Quoted[T @Annot($value)] }`
	`12`	`+ '{ new Quoted[T @Annot($value)]: Quoted[T] } // ascription is added to ensure that the splice of the annotation does not leak outside of the quote`
`13`	`13`	`}`