Merge pull request scala#3224 from soc/SI-7971

SI-7971 Handle static field initializers correctly

Author: adriaanm

src/compiler/scala/tools/nsc/transform/CleanUp.scala

@@ -11,7 +11,7 @@ import Flags._
 import scala.collection._
 import scala.language.postfixOps
 
-abstract class CleanUp extends Transform with ast.TreeDSL {
+abstract class CleanUp extends Statics with Transform with ast.TreeDSL {
   import global._
   import definitions._
   import CODE._
@@ -35,7 +35,7 @@ abstract class CleanUp extends Transform with ast.TreeDSL {
   protected def newTransformer(unit: CompilationUnit): Transformer =
     new CleanUpTransformer(unit)
 
-  class CleanUpTransformer(unit: CompilationUnit) extends Transformer {
+  class CleanUpTransformer(unit: CompilationUnit) extends StaticsTransformer {
     private val newStaticMembers      = mutable.Buffer.empty[Tree]
     private val newStaticInits        = mutable.Buffer.empty[Tree]
     private val symbolsStoredAsStatic = mutable.Map.empty[String, Symbol]
@@ -49,7 +49,7 @@ abstract class CleanUp extends Transform with ast.TreeDSL {
       clearStatics()
       val newBody = transformTrees(body)
       val templ   = deriveTemplate(tree)(_ => transformTrees(newStaticMembers.toList) ::: newBody)
-      try addStaticInits(templ) // postprocess to include static ctors
+      try addStaticInits(templ, newStaticInits, localTyper) // postprocess to include static ctors
       finally clearStatics()
     }
     private def mkTerm(prefix: String): TermName = unit.freshTermName(prefix)
@@ -557,44 +557,6 @@ abstract class CleanUp extends Transform with ast.TreeDSL {
       })
     }
 
-    /* finds the static ctor DefDef tree within the template if it exists. */
-    private def findStaticCtor(template: Template): Option[Tree] =
-      template.body find {
-        case defdef @ DefDef(_, nme.CONSTRUCTOR, _, _, _, _) => defdef.symbol.hasStaticFlag
-        case _ => false
-      }
-
-    /* changes the template for the class so that it contains a static constructor with symbol fields inits,
-     * augments an existing static ctor if one already existed.
-     */
-    private def addStaticInits(template: Template): Template = {
-      if (newStaticInits.isEmpty)
-        template
-      else {
-        val newCtor = findStaticCtor(template) match {
-          // in case there already were static ctors - augment existing ones
-          // currently, however, static ctors aren't being generated anywhere else
-          case Some(ctor @ DefDef(_,_,_,_,_,_)) =>
-            // modify existing static ctor
-            deriveDefDef(ctor) {
-              case block @ Block(stats, expr) =>
-                // need to add inits to existing block
-                treeCopy.Block(block, newStaticInits.toList ::: stats, expr)
-              case term: TermTree =>
-                // need to create a new block with inits and the old term
-                treeCopy.Block(term, newStaticInits.toList, term)
-            }
-          case _ =>
-            // create new static ctor
-            val staticCtorSym  = currentClass.newStaticConstructor(template.pos)
-            val rhs            = Block(newStaticInits.toList, Literal(Constant(())))
-
-            localTyper.typedPos(template.pos)(DefDef(staticCtorSym, rhs))
-        }
-        deriveTemplate(template)(newCtor :: _)
-      }
-    }
-
   } // CleanUpTransformer
 
 }

src/compiler/scala/tools/nsc/transform/Constructors.scala

@@ -13,7 +13,7 @@ import symtab.Flags._
 /** This phase converts classes with parameters into Java-like classes with
  *  fields, which are assigned to from constructors.
  */
-abstract class Constructors extends Transform with ast.TreeDSL {
+abstract class Constructors extends Statics with Transform with ast.TreeDSL {
   import global._
   import definitions._
 
@@ -199,7 +199,7 @@ abstract class Constructors extends Transform with ast.TreeDSL {
         detectUsages walk auxConstructorBuf
       }
     }
-    def mustbeKept(sym: Symbol) = !omittables(sym)
+    def mustBeKept(sym: Symbol) = !omittables(sym)
 
   } // OmittablesHelper
 
@@ -458,7 +458,7 @@ abstract class Constructors extends Transform with ast.TreeDSL {
   } // GuardianOfCtorStmts
 
   private class TemplateTransformer(val unit: CompilationUnit, val impl: Template)
-    extends Transformer
+    extends StaticsTransformer
     with    DelayedInitHelper
     with    OmittablesHelper
     with    GuardianOfCtorStmts {
@@ -607,7 +607,7 @@ abstract class Constructors extends Transform with ast.TreeDSL {
     // follow the primary constructor
     val auxConstructorBuf = new ListBuffer[Tree]
 
-    // The list of statements that go into constructor after and including the superclass constructor call
+    // The list of statements that go into the constructor after and including the superclass constructor call
     val constrStatBuf = new ListBuffer[Tree]
 
     // The list of early initializer statements that go into constructor before the superclass constructor call
@@ -616,6 +616,9 @@ abstract class Constructors extends Transform with ast.TreeDSL {
     // The early initialized field definitions of the class (these are the class members)
     val presupers = treeInfo.preSuperFields(stats)
 
+    // The list of statements that go into the class initializer
+    val classInitStatBuf = new ListBuffer[Tree]
+
     // generate code to copy pre-initialized fields
     for (stat <- constrBody.stats) {
       constrStatBuf += stat
@@ -644,7 +647,7 @@ abstract class Constructors extends Transform with ast.TreeDSL {
             else if (stat.symbol.isConstructor) auxConstructorBuf += stat
             else defBuf += stat
         }
-      case ValDef(_, _, _, rhs) =>
+      case ValDef(mods, _, _, rhs) if !mods.hasStaticFlag =>
         // val defs with constant right-hand sides are eliminated.
         // for all other val defs, an empty valdef goes into the template and
         // the initializer goes as an assignment into the constructor
@@ -659,6 +662,11 @@ abstract class Constructors extends Transform with ast.TreeDSL {
           }
           defBuf += deriveValDef(stat)(_ => EmptyTree)
         }
+      case ValDef(_, _, _, rhs) =>
+        // Add static initializer statements to classInitStatBuf and remove the rhs from the val def.
+        classInitStatBuf += mkAssign(stat.symbol, rhs)
+        defBuf += deriveValDef(stat)(_ => EmptyTree)
+
       case ClassDef(_, _, _, _) =>
         // classes are treated recursively, and left in the template
         defBuf += new ConstructorTransformer(unit).transform(stat)
@@ -670,7 +678,7 @@ abstract class Constructors extends Transform with ast.TreeDSL {
     populateOmittables()
 
     // Initialize all parameters fields that must be kept.
-    val paramInits = paramAccessors filter mustbeKept map { acc =>
+    val paramInits = paramAccessors filter mustBeKept map { acc =>
       // Check for conflicting symbol amongst parents: see bug #1960.
       // It would be better to mangle the constructor parameter name since
       // it can only be used internally, but I think we need more robust name
@@ -710,11 +718,13 @@ abstract class Constructors extends Transform with ast.TreeDSL {
     defBuf ++= auxConstructorBuf
 
     // Unlink all fields that can be dropped from class scope
-    for (sym <- clazz.info.decls ; if !mustbeKept(sym))
+    for (sym <- clazz.info.decls ; if !mustBeKept(sym))
       clazz.info.decls unlink sym
 
     // Eliminate all field definitions that can be dropped from template
-    val transformed: Template = deriveTemplate(impl)(_ => defBuf.toList filter (stat => mustbeKept(stat.symbol)))
+    val templateWithoutOmittables: Template = deriveTemplate(impl)(_ => defBuf.toList filter (stat => mustBeKept(stat.symbol)))
+    //  Add the static initializers
+    val transformed: Template = addStaticInits(templateWithoutOmittables, classInitStatBuf, localTyper)
 
   } // TemplateTransformer
 

src/compiler/scala/tools/nsc/transform/Statics.scala

@@ -0,0 +1,52 @@
+package scala.tools.nsc
+package transform
+
+import symtab._
+import Flags._
+
+import collection.mutable.Buffer
+
+abstract class Statics extends Transform with ast.TreeDSL {
+  import global._
+
+  class StaticsTransformer extends Transformer {
+
+    /** finds the static ctor DefDef tree within the template if it exists. */
+    def findStaticCtor(template: Template): Option[Tree] =
+      template.body find {
+        case defdef @ DefDef(_, nme.CONSTRUCTOR, _, _, _, _) => defdef.symbol.hasStaticFlag
+        case _ => false
+      }
+
+    /** changes the template for the class so that it contains a static constructor with symbol fields inits,
+      * augments an existing static ctor if one already existed.
+      */
+    def addStaticInits(template: Template, newStaticInits: Buffer[Tree], localTyper: analyzer.Typer): Template = {
+      if (newStaticInits.isEmpty)
+        template
+      else {
+        val newCtor = findStaticCtor(template) match {
+          // in case there already were static ctors - augment existing ones
+          // currently, however, static ctors aren't being generated anywhere else
+          case Some(ctor @ DefDef(_,_,_,_,_,_)) =>
+            // modify existing static ctor
+            deriveDefDef(ctor) {
+              case block @ Block(stats, expr) =>
+                // need to add inits to existing block
+                treeCopy.Block(block, newStaticInits.toList ::: stats, expr)
+              case term: TermTree =>
+                // need to create a new block with inits and the old term
+                treeCopy.Block(term, newStaticInits.toList, term)
+            }
+          case _ =>
+            // create new static ctor
+            val staticCtorSym  = currentClass.newStaticConstructor(template.pos)
+            val rhs            = Block(newStaticInits.toList, Literal(Constant(())))
+
+            localTyper.typedPos(template.pos)(DefDef(staticCtorSym, rhs))
+        }
+        deriveTemplate(template)(newCtor :: _)
+      }
+    }
+  }
+}