Support use-site meta-annotations (#16445)

Fixes #12492
Fixes #15318

Author: lrytz

compiler/src/dotty/tools/dotc/core/Annotations.scala

@@ -2,12 +2,13 @@ package dotty.tools
 package dotc
 package core
 
-import Symbols._, Types._, Contexts._, Constants._
-import dotty.tools.dotc.ast.tpd, tpd.*
+import Symbols._, Types._, Contexts._, Constants._, Phases.*
+import ast.tpd, tpd.*
 import util.Spans.Span
 import printing.{Showable, Printer}
 import printing.Texts.Text
-import annotation.internal.sharable
+
+import scala.annotation.internal.sharable
 
 object Annotations {
 
@@ -87,6 +88,22 @@ object Annotations {
     def sameAnnotation(that: Annotation)(using Context): Boolean =
       symbol == that.symbol && tree.sameTree(that.tree)
 
+    def hasOneOfMetaAnnotation(metaSyms: Set[Symbol], orNoneOf: Set[Symbol] = Set.empty)(using Context): Boolean = atPhaseNoLater(erasurePhase) {
+      def go(metaSyms: Set[Symbol]) =
+        def recTp(tp: Type): Boolean = tp.dealiasKeepAnnots match
+          case AnnotatedType(parent, metaAnnot) => metaSyms.exists(metaAnnot.matches) || recTp(parent)
+          case _ => false
+        def rec(tree: Tree): Boolean = methPart(tree) match
+          case New(tpt) => rec(tpt)
+          case Select(qual, _) => rec(qual)
+          case Annotated(arg, metaAnnot) => metaSyms.exists(metaAnnot.tpe.classSymbol.derivesFrom) || rec(arg)
+          case t @ Ident(_) => recTp(t.tpe)
+          case Typed(expr, _) => rec(expr)
+          case _ => false
+        metaSyms.exists(symbol.hasAnnotation) || rec(tree)
+      go(metaSyms) || orNoneOf.nonEmpty && !go(orNoneOf)
+    }
+
     /** Operations for hash-consing, can be overridden */
     def hash: Int = System.identityHashCode(this)
     def eql(that: Annotation) = this eq that

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -1023,6 +1023,8 @@ class Definitions {
   @tu lazy val UncheckedVarianceAnnot: ClassSymbol = requiredClass("scala.annotation.unchecked.uncheckedVariance")
   @tu lazy val VolatileAnnot: ClassSymbol = requiredClass("scala.volatile")
   @tu lazy val WithPureFunsAnnot: ClassSymbol = requiredClass("scala.annotation.internal.WithPureFuns")
+  @tu lazy val BeanGetterMetaAnnot: ClassSymbol = requiredClass("scala.annotation.meta.beanGetter")
+  @tu lazy val BeanSetterMetaAnnot: ClassSymbol = requiredClass("scala.annotation.meta.beanSetter")
   @tu lazy val FieldMetaAnnot: ClassSymbol = requiredClass("scala.annotation.meta.field")
   @tu lazy val GetterMetaAnnot: ClassSymbol = requiredClass("scala.annotation.meta.getter")
   @tu lazy val ParamMetaAnnot: ClassSymbol = requiredClass("scala.annotation.meta.param")
@@ -1039,8 +1041,10 @@ class Definitions {
   @tu lazy val JavaRepeatableAnnot: ClassSymbol = requiredClass("java.lang.annotation.Repeatable")
 
   // A list of meta-annotations that are relevant for fields and accessors
-  @tu lazy val FieldAccessorMetaAnnots: Set[Symbol] =
+  @tu lazy val NonBeanMetaAnnots: Set[Symbol] =
     Set(FieldMetaAnnot, GetterMetaAnnot, ParamMetaAnnot, SetterMetaAnnot)
+  @tu lazy val MetaAnnots: Set[Symbol] =
+    NonBeanMetaAnnots + BeanGetterMetaAnnot + BeanSetterMetaAnnot
 
   // A list of annotations that are commonly used to indicate that a field/method argument or return
   // type is not null. These annotations are used by the nullification logic in JavaNullInterop to

compiler/src/dotty/tools/dotc/core/SymDenotations.scala

@@ -252,6 +252,15 @@ object SymDenotations {
     final def filterAnnotations(p: Annotation => Boolean)(using Context): Unit =
       annotations = annotations.filterConserve(p)
 
+    def annotationsCarrying(meta: Set[Symbol], orNoneOf: Set[Symbol] = Set.empty)(using Context): List[Annotation] =
+      annotations.filterConserve(_.hasOneOfMetaAnnotation(meta, orNoneOf = orNoneOf))
+
+    def copyAndKeepAnnotationsCarrying(phase: DenotTransformer, meta: Set[Symbol], orNoneOf: Set[Symbol] = Set.empty)(using Context): Unit =
+      if annotations.nonEmpty then
+        val cpy = copySymDenotation()
+        cpy.annotations = annotationsCarrying(meta, orNoneOf = orNoneOf)
+        cpy.installAfter(phase)
+
     /** Optionally, the annotation matching the given class symbol */
     final def getAnnotation(cls: Symbol)(using Context): Option[Annotation] =
       dropOtherAnnotations(annotations, cls) match {

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

@@ -5,7 +5,8 @@ import core._
 import ast.tpd._
 import Annotations._
 import Contexts._
-import Symbols.newSymbol
+import Symbols.*
+import SymUtils.*
 import Decorators._
 import Flags._
 import Names._
@@ -23,8 +24,6 @@ class BeanProperties(thisPhase: DenotTransformer):
     } ::: origBody)
 
   def generateAccessors(valDef: ValDef)(using Context): List[Tree] =
-    import Symbols.defn
-
     def generateGetter(valDef: ValDef, annot: Annotation)(using Context) : Tree =
       val prefix = if annot matches defn.BooleanBeanPropertyAnnot then "is" else "get"
       val meth = newSymbol(
@@ -34,9 +33,9 @@ class BeanProperties(thisPhase: DenotTransformer):
         info = MethodType(Nil, valDef.denot.info),
         coord = annot.tree.span
       ).enteredAfter(thisPhase).asTerm
-      meth.addAnnotations(valDef.symbol.annotations)
+       .withAnnotationsCarrying(valDef.symbol, defn.BeanGetterMetaAnnot)
       val body: Tree = ref(valDef.symbol)
-      DefDef(meth, body)
+      DefDef(meth, body).withSpan(meth.span)
 
     def maybeGenerateSetter(valDef: ValDef, annot: Annotation)(using Context): Option[Tree] =
       Option.when(valDef.denot.asSymDenotation.flags.is(Mutable)) {
@@ -48,9 +47,9 @@ class BeanProperties(thisPhase: DenotTransformer):
           info = MethodType(valDef.name :: Nil, valDef.denot.info :: Nil, defn.UnitType),
           coord = annot.tree.span
         ).enteredAfter(thisPhase).asTerm
-        meth.addAnnotations(valDef.symbol.annotations)
+         .withAnnotationsCarrying(valDef.symbol, defn.BeanSetterMetaAnnot)
         def body(params: List[List[Tree]]): Tree = Assign(ref(valDef.symbol), params.head.head)
-        DefDef(meth, body)
+        DefDef(meth, body).withSpan(meth.span)
       }
 
     def prefixedName(prefix: String, valName: Name) =

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

@@ -4,7 +4,7 @@ package transform
 import core._
 import DenotTransformers._
 import Contexts._
-import Phases.phaseOf
+import Phases.*
 import SymDenotations.SymDenotation
 import Denotations._
 import Symbols._
@@ -114,26 +114,10 @@ class Memoize extends MiniPhase with IdentityDenotTransformer { thisPhase =>
         flags = Private | (if (sym.is(StableRealizable)) EmptyFlags else Mutable),
         info  = fieldType,
         coord = tree.span
-      ).withAnnotationsCarrying(sym, defn.FieldMetaAnnot)
+      ).withAnnotationsCarrying(sym, defn.FieldMetaAnnot, orNoneOf = defn.MetaAnnots)
        .enteredAfter(thisPhase)
     }
 
-    def addAnnotations(denot: Denotation): Unit =
-      denot match {
-        case fieldDenot: SymDenotation if sym.annotations.nonEmpty =>
-          val cpy = fieldDenot.copySymDenotation()
-          cpy.annotations = sym.annotations
-          cpy.installAfter(thisPhase)
-        case _ => ()
-      }
-
-    def removeUnwantedAnnotations(denot: SymDenotation, metaAnnotSym: ClassSymbol): Unit =
-      if (sym.annotations.nonEmpty) {
-        val cpy = sym.copySymDenotation()
-        cpy.filterAnnotations(_.symbol.hasAnnotation(metaAnnotSym))
-        cpy.installAfter(thisPhase)
-      }
-
     val NoFieldNeeded = Lazy | Deferred | JavaDefined | Inline
 
     def erasedBottomTree(sym: Symbol) =
@@ -183,8 +167,7 @@ class Memoize extends MiniPhase with IdentityDenotTransformer { thisPhase =>
             if isErasableBottomField(field, rhsClass) then erasedBottomTree(rhsClass)
             else transformFollowingDeep(ref(field))(using ctx.withOwner(sym))
           val getterDef = cpy.DefDef(tree)(rhs = getterRhs)
-          addAnnotations(fieldDef.denot)
-          removeUnwantedAnnotations(sym, defn.GetterMetaAnnot)
+          sym.copyAndKeepAnnotationsCarrying(thisPhase, Set(defn.GetterMetaAnnot))
           Thicket(fieldDef, getterDef)
       else if sym.isSetter then
         if (!sym.is(ParamAccessor)) { val Literal(Constant(())) = tree.rhs: @unchecked } // This is intended as an assertion
@@ -210,7 +193,7 @@ class Memoize extends MiniPhase with IdentityDenotTransformer { thisPhase =>
             then Literal(Constant(()))
             else Assign(ref(field), adaptToField(field, ref(tree.termParamss.head.head.symbol)))
           val setterDef = cpy.DefDef(tree)(rhs = transformFollowingDeep(initializer)(using ctx.withOwner(sym)))
-          removeUnwantedAnnotations(sym, defn.SetterMetaAnnot)
+          sym.copyAndKeepAnnotationsCarrying(thisPhase, Set(defn.SetterMetaAnnot))
           setterDef
       else
         // Curiously, some accessors from Scala2 have ' ' suffixes.

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

@@ -1,4 +1,5 @@
-package dotty.tools.dotc
+package dotty.tools
+package dotc
 package transform
 
 import core._
@@ -147,6 +148,7 @@ class Pickler extends Phase {
     if unequal then
       output("before-pickling.txt", previous)
       output("after-pickling.txt", unpickled)
+      //sys.process.Process("diff -u before-pickling.txt after-pickling.txt").!
       report.error(em"""pickling difference for $cls in ${cls.source}, for details:
                     |
                     |  diff before-pickling.txt after-pickling.txt""")

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

@@ -1,4 +1,5 @@
-package dotty.tools.dotc
+package dotty.tools
+package dotc
 package transform
 
 import dotty.tools.dotc.ast.{Trees, tpd, untpd, desugar}
@@ -156,12 +157,14 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer { thisPhase
           checkInferredWellFormed(tree.tpt)
           if sym.is(Method) then
             if sym.isSetter then
-              removeUnwantedAnnotations(sym, defn.SetterMetaAnnot, NoSymbol, keepIfNoRelevantAnnot = false)
+              sym.copyAndKeepAnnotationsCarrying(thisPhase, Set(defn.SetterMetaAnnot))
           else
             if sym.is(Param) then
-              removeUnwantedAnnotations(sym, defn.ParamMetaAnnot, NoSymbol, keepIfNoRelevantAnnot = true)
+              sym.copyAndKeepAnnotationsCarrying(thisPhase, Set(defn.ParamMetaAnnot), orNoneOf = defn.NonBeanMetaAnnots)
+            else if sym.is(ParamAccessor) then
+              sym.copyAndKeepAnnotationsCarrying(thisPhase, Set(defn.GetterMetaAnnot, defn.FieldMetaAnnot))
             else
-              removeUnwantedAnnotations(sym, defn.GetterMetaAnnot, defn.FieldMetaAnnot, keepIfNoRelevantAnnot = !sym.is(ParamAccessor))
+              sym.copyAndKeepAnnotationsCarrying(thisPhase, Set(defn.GetterMetaAnnot, defn.FieldMetaAnnot), orNoneOf = defn.NonBeanMetaAnnots)
           if sym.isScala2Macro && !ctx.settings.XignoreScala2Macros.value then
             if !sym.owner.unforcedDecls.exists(p => !p.isScala2Macro && p.name == sym.name && p.signature == sym.signature)
                // Allow scala.reflect.materializeClassTag to be able to compile scala/reflect/package.scala
@@ -183,17 +186,6 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer { thisPhase
         => Checking.checkAppliedTypesIn(tree)
       case _ =>
 
-    private def removeUnwantedAnnotations(sym: Symbol, metaAnnotSym: Symbol,
-        metaAnnotSymBackup: Symbol, keepIfNoRelevantAnnot: Boolean)(using Context): Unit =
-      def shouldKeep(annot: Annotation): Boolean =
-        val annotSym = annot.symbol
-        annotSym.hasAnnotation(metaAnnotSym)
-          || annotSym.hasAnnotation(metaAnnotSymBackup)
-          || (keepIfNoRelevantAnnot && {
-            !annotSym.annotations.exists(metaAnnot => defn.FieldAccessorMetaAnnots.contains(metaAnnot.symbol))
-          })
-      if sym.annotations.nonEmpty then
-        sym.filterAnnotations(shouldKeep(_))
 
     private def transformSelect(tree: Select, targs: List[Tree])(using Context): Tree = {
       val qual = tree.qualifier

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

@@ -270,11 +270,8 @@ object SymUtils:
     def isEnumCase(using Context): Boolean =
       self.isAllOf(EnumCase, butNot = JavaDefined)
 
-    def annotationsCarrying(meta: ClassSymbol)(using Context): List[Annotation] =
-      self.annotations.filter(_.symbol.hasAnnotation(meta))
-
-    def withAnnotationsCarrying(from: Symbol, meta: ClassSymbol)(using Context): self.type = {
-      self.addAnnotations(from.annotationsCarrying(meta))
+    def withAnnotationsCarrying(from: Symbol, meta: Symbol, orNoneOf: Set[Symbol] = Set.empty)(using Context): self.type = {
+      self.addAnnotations(from.annotationsCarrying(Set(meta), orNoneOf))
       self
     }
 

compiler/src/dotty/tools/dotc/util/Spans.scala

@@ -182,6 +182,7 @@ object Spans {
       assert(isSpan)
       if (this == NoCoord) NoSpan else Span(-1 - encoding)
     }
+    override def toString = if isSpan then s"$toSpan" else s"Coord(idx=$toIndex)"
   }
 
   /** An index coordinate */

tests/run/beans.check

@@ -2,5 +2,6 @@
 true
 10
 [@beans.LibraryAnnotation_1()]
+[]
 some text
 other text