Add compiler phases to set and unset symbol.defTree

Author: liufengyun

compiler/src/dotty/tools/dotc/Compiler.scala

@@ -57,7 +57,8 @@ class Compiler {
          new CheckReentrant,         // Internal use only: Check that compiled program has no data races involving global vars
          new ElimPackagePrefixes,    // Eliminate references to package prefixes in Select nodes
          new CookComments,           // Cook the comments: expand variables, doc, etc.
-         new CompleteJavaEnums) ::   // Fill in constructors for Java enums
+         new CompleteJavaEnums,      // Fill in constructors for Java enums
+         new SetDefTree) ::          // set `symbol.defTree`
     List(new CheckStatic,            // Check restrictions that apply to @static members
          new ElimRepeated,           // Rewrite vararg parameters and arguments
          new ExpandSAMs,             // Expand single abstract method closures to anonymous classes
@@ -68,7 +69,8 @@ class Compiler {
          new ByNameClosures,         // Expand arguments to by-name parameters to closures
          new HoistSuperArgs,         // Hoist complex arguments of supercalls to enclosing scope
          new ClassOf,                // Expand `Predef.classOf` calls.
-         new RefChecks) ::           // Various checks mostly related to abstract members and overriding
+         new RefChecks,              // Various checks mostly related to abstract members and overriding
+         new SetDefTreeOff) ::       // unset `symbol.defTree`
     List(new ElimOpaque,             // Turn opaque into normal aliases
          new TryCatchPatterns,       // Compile cases in try/catch
          new PatternMatcher,         // Compile pattern matches

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

@@ -113,7 +113,6 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer { thisPhase
       val sym = tree.symbol
       Checking.checkValidOperator(sym)
       sym.transformAnnotations(transformAnnot)
-      sym.defTree = tree
       tree
     }
 

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

@@ -0,0 +1,30 @@
+package dotty.tools.dotc.transform
+
+import dotty.tools.dotc.ast.tpd
+import dotty.tools.dotc.core.Contexts.Context
+import dotty.tools.dotc.transform.MegaPhase._
+
+/** Set the `defTree` property of symbols for compile plugins
+ *  that perform "whole-program" analysis.
+ *
+ *  All plugins that depend on `symbol.defTree` should sit
+ *  between the phase `SetDefTree` and `SetDefTreeOff`.
+ */
+class SetDefTree extends MiniPhase {
+  import tpd._
+
+  override val phaseName: String = SetDefTree.name
+  override def runsAfter: Set[String] = Set(Pickler.name)
+    // don't allow plugins to change tasty
+    // research plugins can still change the phase plan at will
+
+  override def transformValDef(tree: ValDef)(implicit ctx: Context): Tree = tree.setDefTree
+
+  override def transformDefDef(tree: DefDef)(implicit ctx: Context): Tree = tree.setDefTree
+
+  override def transformTypeDef(tree: TypeDef)(implicit ctx: Context): Tree = tree.setDefTree
+}
+
+object SetDefTree {
+  val name: String = "SetDefTree"
+}

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

@@ -0,0 +1,32 @@
+package dotty.tools.dotc.transform
+
+import dotty.tools.dotc.ast.tpd
+import dotty.tools.dotc.core.Contexts.Context
+import dotty.tools.dotc.transform.MegaPhase._
+
+/** Unset the `defTree` property of symbols. See the doc for `SetDefTree` */
+class SetDefTreeOff extends MiniPhase {
+  import tpd._
+
+  override val phaseName: String = SetDefTreeOff.name
+  override def runsAfter: Set[String] = Set(SetDefTree.name)
+
+  override def transformValDef(tree: ValDef)(implicit ctx: Context): Tree = {
+    tree.symbol.defTree = EmptyTree
+    tree
+  }
+
+  override def transformDefDef(tree: DefDef)(implicit ctx: Context): Tree = {
+    tree.symbol.defTree = EmptyTree
+    tree
+  }
+
+  override def transformTypeDef(tree: TypeDef)(implicit ctx: Context): Tree = {
+    tree.symbol.defTree = EmptyTree
+    tree
+  }
+}
+
+object SetDefTreeOff {
+  val name: String = "SetDefTreeOff"
+}

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

@@ -222,7 +222,7 @@ class SyntheticMembers(thisPhase: DenotTransformer) {
      *
      */
     def equalsBody(that: Tree)(implicit ctx: Context): Tree = {
-      val thatAsClazz = ctx.newSymbol(ctx.owner, nme.x_0, Synthetic, clazzType, coord = ctx.owner.span) // x$0
+      val thatAsClazz = ctx.newSymbol(ctx.owner, nme.x_0, Synthetic | Case, clazzType, coord = ctx.owner.span) // x$0
       def wildcardAscription(tp: Type) = Typed(Underscore(tp), TypeTree(tp))
       val pattern = Bind(thatAsClazz, wildcardAscription(AnnotatedType(clazzType, Annotation(defn.UncheckedAnnot)))) // x$0 @ (_: C @unchecked)
       // compare primitive fields first, slow equality checks of non-primitive fields can be skipped when primitives differ