Merge pull request #1543 from adriaanm/paulp-add-synthetics-once

SI-6578 Harden against synthetics being added more than once.

1 files changed, 25 insertions, 6 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala b/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
index cc3d980cf1..001acc7a80 100644
--- a/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
@@ -36,11 +36,31 @@ trait SyntheticMethods extends ast.TreeDSL {
   import definitions._
   import CODE._
 
+  private lazy val productSymbols    = List(Product_productPrefix, Product_productArity, Product_productElement, Product_iterator, Product_canEqual)
+  private lazy val valueSymbols      = List(Any_hashCode, Any_equals)
+  private lazy val caseSymbols       = List(Object_hashCode, Object_toString) ::: productSymbols
+  private lazy val caseValueSymbols  = Any_toString :: valueSymbols ::: productSymbols
+  private lazy val caseObjectSymbols = Object_equals :: caseSymbols
+  private def symbolsToSynthesize(clazz: Symbol): List[Symbol] = {
+    if (clazz.isCase) {
+      if (clazz.isDerivedValueClass) caseValueSymbols
+      else if (clazz.isModuleClass) caseSymbols
+      else caseObjectSymbols
+    }
+    else if (clazz.isDerivedValueClass) valueSymbols
+    else Nil
+  }
+
   /** Add the synthetic methods to case classes.
    */
   def addSyntheticMethods(templ: Template, clazz0: Symbol, context: Context): Template = {
-
-    if (phase.erasedTypes)
+    val syntheticsOk = (phase.id <= currentRun.typerPhase.id) && {
+      symbolsToSynthesize(clazz0) filter (_ matchingSymbol clazz0.info isSynthetic) match {
+        case Nil  => true
+        case syms => log("Not adding synthetic methods: already has " + syms.mkString(", ")) ; false
+      }
+    }
+    if (!syntheticsOk)
       return templ
 
     val synthesizer = new ClassMethodSynthesis(
@@ -94,9 +114,9 @@ trait SyntheticMethods extends ast.TreeDSL {
       Apply(gen.mkAttributedRef(method), args.toList)
     }
 
-    // Any member, including private
+    // Any concrete member, including private
     def hasConcreteImpl(name: Name) =
-      clazz.info.member(name).alternatives exists (m => !m.isDeferred && !m.isSynthetic)
+      clazz.info.member(name).alternatives exists (m => !m.isDeferred)
 
     def hasOverridingImplementation(meth: Symbol) = {
       val sym = clazz.info nonPrivateMember meth.name
@@ -347,8 +367,7 @@ trait SyntheticMethods extends ast.TreeDSL {
       (lb ++= templ.body ++= synthesize()).toList
     }
 
-    if (phase.id > currentRun.typerPhase.id) templ
-    else deriveTemplate(templ)(body =>
+    deriveTemplate(templ)(body =>
       if (clazz.isCase) caseTemplateBody()
       else synthesize() match {
         case Nil  => body // avoiding unnecessary copy