Merge pull request scala#6218 from dotty-staging/inliner-fixes

Inliner improvements

compiler/src/dotty/tools/dotc/config/Printers.scala

@@ -34,6 +34,7 @@ object Printers {
   val quotePickling: Printer = noPrinter
   val plugins: Printer = noPrinter
   val simplify: Printer = noPrinter
+  val staging: Printer = noPrinter
   val subtyping: Printer = noPrinter
   val tailrec: Printer = noPrinter
   val transforms: Printer = noPrinter

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

@@ -3,6 +3,7 @@ package transform
 
 import dotty.tools.dotc.ast.Trees._
 import dotty.tools.dotc.ast.{TreeMapWithImplicits, TreeTypeMap, tpd, untpd}
+import dotty.tools.dotc.config.Printers.staging
 import dotty.tools.dotc.core.Constants._
 import dotty.tools.dotc.core.Decorators._
 import dotty.tools.dotc.core.Flags._
@@ -71,7 +72,7 @@ abstract class TreeMapWithStages(@constructorOnly ictx: Context) extends TreeMap
   override def transform(tree: Tree)(implicit ctx: Context): Tree = {
     if (tree.source != ctx.source && tree.source.exists)
       transform(tree)(ctx.withSource(tree.source))
-    else reporting.trace(i"StagingTransformer.transform $tree at $level", show = true) {
+    else reporting.trace(i"StagingTransformer.transform $tree at $level", staging, show = true) {
       def mapOverTree(lastEntered: List[Symbol]) =
         try super.transform(tree)
         finally

compiler/src/dotty/tools/dotc/typer/ErrorReporting.scala

@@ -81,7 +81,7 @@ object ErrorReporting {
       if (tree.tpe.widen.exists)
         i"${exprStr(tree)} does not take ${kind}parameters"
       else {
-        new FatalError("").printStackTrace()
+        //new FatalError("").printStackTrace()  //DEBUG
         i"undefined: $tree # ${tree.uniqueId}: ${tree.tpe.toString} at ${ctx.phase}"
       }
 

compiler/src/dotty/tools/dotc/typer/Implicits.scala

@@ -773,7 +773,7 @@ trait Implicits { self: Typer =>
               success(Literal(c))
             case TypeRef(_, sym) if sym == defn.UnitClass =>
               success(Literal(Constant(())))
-            case n: NamedType =>
+            case n: TermRef =>
               success(ref(n))
             case tp =>
               EmptyTree

compiler/src/dotty/tools/dotc/typer/Inliner.scala

@@ -239,7 +239,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
   /** A buffer for bindings that define proxies for actual arguments */
   private val bindingsBuf = new mutable.ListBuffer[ValOrDefDef]
 
-  private def newSym(name: Name, flags: FlagSet, info: Type): Symbol =
+  private def newSym(name: Name, flags: FlagSet, info: Type)(implicit ctx: Context): Symbol =
     ctx.newSymbol(ctx.owner, name, flags, info, coord = call.span)
 
   /** A binding for the parameter of an inline method. This is a `val` def for
@@ -732,35 +732,40 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
       val gadtSyms = typer.gadtSyms(scrutType)
 
       /** Try to match pattern `pat` against scrutinee reference `scrut`. If successful add
-       *  bindings for variables bound in this pattern to `bindingsBuf`.
+       *  bindings for variables bound in this pattern to `caseBindingMap`.
        */
       def reducePattern(
-        bindingsBuf: mutable.ListBuffer[ValOrDefDef],
-        fromBuf: mutable.ListBuffer[TypeSymbol],
-        toBuf: mutable.ListBuffer[TypeSymbol],
+        caseBindingMap: mutable.ListBuffer[(Symbol, MemberDef)],
         scrut: TermRef,
         pat: Tree
       )(implicit ctx: Context): Boolean = {
 
       	/** Create a binding of a pattern bound variable with matching part of
       	 *  scrutinee as RHS and type that corresponds to RHS.
       	 */
-        def newBinding(sym: TermSymbol, rhs: Tree): Unit = {
-          sym.info = rhs.tpe.widenTermRefExpr
-          bindingsBuf += ValDef(sym, constToLiteral(rhs)).withSpan(sym.span)
+        def newTermBinding(sym: TermSymbol, rhs: Tree): Unit = {
+          val copied = sym.copy(info = rhs.tpe.widenTermRefExpr, coord = sym.coord).asTerm
+          caseBindingMap += ((sym, ValDef(copied, constToLiteral(rhs)).withSpan(sym.span)))
+        }
+
+        def newTypeBinding(sym: TypeSymbol, alias: Type): Unit = {
+          val copied = sym.copy(info = TypeAlias(alias), coord = sym.coord).asType
+          caseBindingMap += ((sym, TypeDef(copied)))
         }
 
         def searchImplicit(sym: TermSymbol, tpt: Tree) = {
           val evTyper = new Typer
-          val evidence = evTyper.inferImplicitArg(tpt.tpe, tpt.span)(ctx.fresh.setTyper(evTyper))
+          val evCtx = ctx.fresh.setTyper(evTyper)
+          val evidence = evTyper.inferImplicitArg(tpt.tpe, tpt.span)(evCtx)
           evidence.tpe match {
             case fail: Implicits.AmbiguousImplicits =>
               ctx.error(evTyper.missingArgMsg(evidence, tpt.tpe, ""), tpt.sourcePos)
               true // hard error: return true to stop implicit search here
             case fail: Implicits.SearchFailureType =>
               false
             case _ =>
-              newBinding(sym, evidence)
+              //inliner.println(i"inferred implicit $sym: ${sym.info} with $evidence: ${evidence.tpe.widen}, ${evCtx.gadt.constraint}, ${evCtx.typerState.constraint}")
+              newTermBinding(sym, evidence)
               true
           }
         }
@@ -810,27 +815,25 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
           extractBindVariance(SimpleIdentityMap.Empty, tpt.tpe)
         }
 
+        def addTypeBindings(typeBinds: TypeBindsMap)(implicit ctx: Context): Unit =
+          typeBinds.foreachBinding { case (sym, shouldBeMinimized) =>
+            newTypeBinding(sym, ctx.gadt.approximation(sym, fromBelow = shouldBeMinimized))
+          }
+
         def registerAsGadtSyms(typeBinds: TypeBindsMap)(implicit ctx: Context): Unit =
           typeBinds.foreachBinding { case (sym, _) =>
             val TypeBounds(lo, hi) = sym.info.bounds
             ctx.gadt.addBound(sym, lo, isUpper = false)
             ctx.gadt.addBound(sym, hi, isUpper = true)
           }
 
-        def addTypeBindings(typeBinds: TypeBindsMap)(implicit ctx: Context): Unit =
-          typeBinds.foreachBinding { case (sym, shouldBeMinimized) =>
-            val copied = sym.copy(info = TypeAlias(ctx.gadt.approximation(sym, fromBelow = shouldBeMinimized))).asType
-            fromBuf += sym
-            toBuf += copied
-          }
-
         pat match {
           case Typed(pat1, tpt) =>
             val typeBinds = getTypeBindsMap(pat1, tpt)
             registerAsGadtSyms(typeBinds)
             scrut <:< tpt.tpe && {
               addTypeBindings(typeBinds)
-              reducePattern(bindingsBuf, fromBuf, toBuf, scrut, pat1)
+              reducePattern(caseBindingMap, scrut, pat1)
             }
           case pat @ Bind(name: TermName, Typed(_, tpt)) if isImplicit =>
             val typeBinds = getTypeBindsMap(tpt, tpt)
@@ -840,8 +843,8 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
               true
             }
           case pat @ Bind(name: TermName, body) =>
-            reducePattern(bindingsBuf, fromBuf, toBuf, scrut, body) && {
-              if (name != nme.WILDCARD) newBinding(pat.symbol.asTerm, ref(scrut))
+            reducePattern(caseBindingMap, scrut, body) && {
+              if (name != nme.WILDCARD) newTermBinding(pat.symbol.asTerm, ref(scrut))
               true
             }
           case Ident(nme.WILDCARD) =>
@@ -864,8 +867,8 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
                   case (Nil, Nil) => true
                   case (pat :: pats1, selector :: selectors1) =>
                     val elem = newSym(InlineBinderName.fresh(), Synthetic, selector.tpe.widenTermRefExpr).asTerm
-                    newBinding(elem, selector)
-                    reducePattern(bindingsBuf, fromBuf, toBuf, elem.termRef, pat) &&
+                    caseBindingMap += ((NoSymbol, ValDef(elem, constToLiteral(selector)).withSpan(elem.span)))
+                    reducePattern(caseBindingMap, elem.termRef, pat) &&
                     reduceSubPatterns(pats1, selectors1)
                   case _ => false
                 }
@@ -892,7 +895,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
                 false
             }
           case Inlined(EmptyTree, Nil, ipat) =>
-            reducePattern(bindingsBuf, fromBuf, toBuf, scrut, ipat)
+            reducePattern(caseBindingMap, scrut, ipat)
           case _ => false
         }
       }
@@ -902,32 +905,34 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
       val scrutineeBinding = normalizeBinding(ValDef(scrutineeSym, scrutinee))
 
       def reduceCase(cdef: CaseDef): MatchRedux = {
-        val caseBindingsBuf = new mutable.ListBuffer[ValOrDefDef]()
-        def guardOK(implicit ctx: Context) = cdef.guard.isEmpty || {
-          val guardCtx = ctx.fresh.setNewScope
-          caseBindingsBuf.foreach(binding => guardCtx.enter(binding.symbol))
-          typer.typed(cdef.guard, defn.BooleanType)(guardCtx) match {
-            case ConstantValue(true) => true
-            case _ => false
+        val caseBindingMap = new mutable.ListBuffer[(Symbol, MemberDef)]()
+
+        def substBindings(
+            bindings: List[(Symbol, MemberDef)],
+            bbuf: mutable.ListBuffer[MemberDef],
+            from: List[Symbol], to: List[Symbol]): (List[MemberDef], List[Symbol], List[Symbol]) =
+          bindings match {
+            case (sym, binding) :: rest =>
+              bbuf += binding.subst(from, to).asInstanceOf[MemberDef]
+              if (sym.exists) substBindings(rest, bbuf, sym :: from, binding.symbol :: to)
+              else substBindings(rest, bbuf, from, to)
+            case Nil => (bbuf.toList, from, to)
           }
-        }
-        if (!isImplicit) caseBindingsBuf += scrutineeBinding
+
+        if (!isImplicit) caseBindingMap += ((NoSymbol, scrutineeBinding))
         val gadtCtx = typer.gadtContext(gadtSyms).addMode(Mode.GADTflexible)
-        val fromBuf = mutable.ListBuffer.empty[TypeSymbol]
-        val toBuf = mutable.ListBuffer.empty[TypeSymbol]
-        if (reducePattern(caseBindingsBuf, fromBuf, toBuf, scrutineeSym.termRef, cdef.pat)(gadtCtx) && guardOK) {
-          val caseBindings = caseBindingsBuf.toList
-          val from = fromBuf.toList
-          val to = toBuf.toList
-          if (from.isEmpty) Some((caseBindings, cdef.body))
-          else {
-            val Block(stats, expr) = tpd.Block(caseBindings, cdef.body).subst(from, to)
-            val typeDefs = to.collect { case sym if sym.name != tpnme.WILDCARD => tpd.TypeDef(sym).withSpan(sym.span) }
-            Some((typeDefs ::: stats.asInstanceOf[List[MemberDef]], expr))
+        if (reducePattern(caseBindingMap, scrutineeSym.termRef, cdef.pat)(gadtCtx)) {
+          val (caseBindings, from, to) = substBindings(caseBindingMap.toList, mutable.ListBuffer(), Nil, Nil)
+          val guardOK = cdef.guard.isEmpty || {
+            typer.typed(cdef.guard.subst(from, to), defn.BooleanType) match {
+              case ConstantValue(true) => true
+              case _ => false
+            }
           }
+          if (guardOK) Some((caseBindings, cdef.body.subst(from, to)))
+          else None
         }
-        else
-          None
+        else None
       }
 
       def recur(cases: List[CaseDef]): MatchRedux = cases match {
@@ -1053,8 +1058,29 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
    */
   def dropUnusedDefs(bindings: List[MemberDef], tree: Tree)(implicit ctx: Context): (List[MemberDef], Tree) = {
     // inlining.println(i"drop unused $bindings%, % in $tree")
-
-    def inlineTermBindings(termBindings: List[MemberDef], tree: Tree)(implicit ctx: Context): (List[MemberDef], Tree) = {
+    val (termBindings, typeBindings) = bindings.partition(_.symbol.isTerm)
+    if (typeBindings.nonEmpty) {
+      val typeBindingsSet = typeBindings.foldLeft[SimpleIdentitySet[Symbol]](SimpleIdentitySet.empty)(_ + _.symbol)
+      val inlineTypeBindings = new TreeTypeMap(
+        typeMap = new TypeMap() {
+          override def apply(tp: Type): Type = tp match {
+            case tr: TypeRef if tr.prefix.eq(NoPrefix) && typeBindingsSet.contains(tr.symbol) =>
+              val TypeAlias(res) = tr.info
+              res
+            case tp => mapOver(tp)
+          }
+        },
+        treeMap = {
+          case ident: Ident if ident.isType && typeBindingsSet.contains(ident.symbol) =>
+            val TypeAlias(r) = ident.symbol.info
+            TypeTree(r).withSpan(ident.span)
+          case tree => tree
+        }
+      )
+      val Block(termBindings1, tree1) = inlineTypeBindings(Block(termBindings, tree))
+      dropUnusedDefs(termBindings1.asInstanceOf[List[ValOrDefDef]], tree1)
+    }
+    else {
       val refCount = newMutableSymbolMap[Int]
       val bindingOfSym = newMutableSymbolMap[MemberDef]
 
@@ -1063,7 +1089,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
         case vdef @ ValDef(_, _, _) => isPureExpr(vdef.rhs)
         case _ => false
       }
-      for (binding <- termBindings if isInlineable(binding)) {
+      for (binding <- bindings if isInlineable(binding)) {
         refCount(binding.symbol) = 0
         bindingOfSym(binding.symbol) = binding
       }
@@ -1121,40 +1147,15 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(implicit ctx: Context) {
         }
       }
 
-      val retained = termBindings.filterConserve(binding => retain(binding.symbol))
-      if (retained `eq` termBindings) {
-        (termBindings, tree)
+      val retained = bindings.filterConserve(binding => retain(binding.symbol))
+      if (retained `eq` bindings) {
+        (bindings, tree)
       }
       else {
         val expanded = inlineBindings.transform(tree)
         dropUnusedDefs(retained, expanded)
       }
     }
-
-    val (termBindings, typeBindings) = bindings.partition(_.symbol.isTerm)
-    if (typeBindings.isEmpty) inlineTermBindings(termBindings, tree)
-    else {
-      val typeBindingsSet = typeBindings.foldLeft[SimpleIdentitySet[Symbol]](SimpleIdentitySet.empty)(_ + _.symbol)
-      val inlineTypeBindings = new TreeTypeMap(
-        typeMap = new TypeMap() {
-          override def apply(tp: Type): Type = tp match {
-            case tr: TypeRef if tr.prefix.eq(NoPrefix) && typeBindingsSet.contains(tr.symbol) =>
-              val TypeAlias(res) = tr.info
-              res
-            case tp => mapOver(tp)
-          }
-        },
-        treeMap = {
-          case ident: Ident if ident.isType && typeBindingsSet.contains(ident.symbol) =>
-            val TypeAlias(r) = ident.symbol.info
-            TypeTree(r).withSpan(ident.span)
-          case tree => tree
-        }
-      )
-
-      val Block(termBindings1, tree1) = inlineTypeBindings(Block(termBindings, tree))
-      inlineTermBindings(termBindings1.asInstanceOf[List[ValOrDefDef]], tree1)
-    }
   }
 
   private def expandMacro(body: Tree, span: Span)(implicit ctx: Context) = {

compiler/src/dotty/tools/dotc/typer/RefChecks.scala

@@ -156,8 +156,8 @@ object RefChecks {
    *    1.8.1  M's type is a subtype of O's type, or
    *    1.8.2  M is of type []S, O is of type ()T and S <: T, or
    *    1.8.3  M is of type ()S, O is of type []T and S <: T, or
-   *    1.9.1  If M or O are erased, they must both be erased
-   *    1.9.2  If M or O are extension methods, they must both be extension methods
+   *    1.9.1  If M is erased, O is erased. If O is erased, M is erased or inline.
+   *    1.9.2  If M or O are extension methods, they must both be extension methods.
    *    1.10   If M is an inline or Scala-2 macro method, O cannot be deferred unless
    *           there's also a concrete method that M overrides.
    *    1.11.  If O is a Scala-2 macro, M must be a Scala-2 macro.
@@ -394,7 +394,7 @@ object RefChecks {
         overrideError("must be declared lazy to override a lazy value")
       } else if (member.is(Erased) && !other.is(Erased)) { // (1.9.1)
         overrideError("is erased, cannot override non-erased member")
-      } else if (other.is(Erased) && !member.is(Erased)) { // (1.9.1)
+      } else if (other.is(Erased) && !member.is(Erased | Inline)) { // (1.9.1)
         overrideError("is not erased, cannot override erased member")
       } else if (member.is(Extension) && !other.is(Extension)) { // (1.9.2)
         overrideError("is an extension method, cannot override a normal method")

compiler/test/dotc/run-test-pickling.blacklist

@@ -8,6 +8,7 @@ tuples1a.scala
 typeclass-derivation1.scala
 typeclass-derivation2.scala
 typeclass-derivation2a.scala
+typeclass-derivation2c.scala
 typeclass-derivation3.scala
 derive-generic.scala
 deriving-interesting-prefixes.scala

tests/neg/i6241.scala

@@ -0,0 +1,5 @@
+object Test extends App {
+  inline def v[T] = valueOf[T]  // error
+
+  println(v[String])
+}

tests/pos/implicit-match.scala → tests/pending/pos/implicit-match.scala

@@ -1,3 +1,4 @@
+// Implicit matches that bind parameters don't work yet.
 object `implicit-match` {
   object invariant {
     case class Box[T](value: T)