3 files changed, 28 insertions, 21 deletions

diff --git a/src/dotty/tools/dotc/core/Denotations.scala b/src/dotty/tools/dotc/core/Denotations.scala
index 4ab911160..60a4df9fa 100644
--- a/src/dotty/tools/dotc/core/Denotations.scala
+++ b/src/dotty/tools/dotc/core/Denotations.scala
@@ -12,6 +12,7 @@ import Types._, Periods._, Flags._, Transformers._, Decorators._
 import printing.Texts._
 import printing.Printer
 import io.AbstractFile
+import config.Config
 import Decorators.SymbolIteratorDecorator
 
 
@@ -643,14 +644,15 @@ object Denotations {
     type AsSeenFromResult <: PreDenotation
 
     /** The denotation with info(s) as seen from prefix type */
-    final def asSeenFrom(pre: Type)(implicit ctx: Context): AsSeenFromResult = {
-      if ((cachedPrefix ne pre) || ctx.period != validAsSeenFrom) {
-        cachedAsSeenFrom = computeAsSeenFrom(pre)
-        cachedPrefix = pre
-        validAsSeenFrom = ctx.period
-      }
-      cachedAsSeenFrom
-    }
+    final def asSeenFrom(pre: Type)(implicit ctx: Context): AsSeenFromResult =
+      if (Config.cacheAsSeenFrom) {
+        if ((cachedPrefix ne pre) || ctx.period != validAsSeenFrom) {
+          cachedAsSeenFrom = computeAsSeenFrom(pre)
+          cachedPrefix = pre
+          validAsSeenFrom = ctx.period
+        }
+        cachedAsSeenFrom
+      } else computeAsSeenFrom(pre)
 
     protected def computeAsSeenFrom(pre: Type)(implicit ctx: Context): AsSeenFromResult
 
diff --git a/src/dotty/tools/dotc/core/SymDenotations.scala b/src/dotty/tools/dotc/core/SymDenotations.scala
index d6032aee3..af2e6a8ca 100644
--- a/src/dotty/tools/dotc/core/SymDenotations.scala
+++ b/src/dotty/tools/dotc/core/SymDenotations.scala
@@ -10,6 +10,7 @@ import collection.immutable.BitSet
 import scala.reflect.io.AbstractFile
 import Decorators.SymbolIteratorDecorator
 import annotation.tailrec
+import config.Config
 
 trait SymDenotations { this: Context =>
   import SymDenotations._
@@ -921,14 +922,15 @@ object SymDenotations {
      *  The elements of the returned pre-denotation all
      *  have existing symbols.
      */
-    final def membersNamed(name: Name)(implicit ctx: Context): PreDenotation = {
-      var denots: PreDenotation = memberCache lookup name
-      if (denots == null) {
-        denots = computeMembersNamed(name)
-        memberCache enter (name, denots)
-      }
-      denots
-    }
+    final def membersNamed(name: Name)(implicit ctx: Context): PreDenotation =
+      if (Config.cacheMemberNames) {
+        var denots: PreDenotation = memberCache lookup name
+        if (denots == null) {
+          denots = computeMembersNamed(name)
+          memberCache enter (name, denots)
+        }
+        denots
+      } else computeMembersNamed(name)
 
     private def computeMembersNamed(name: Name)(implicit ctx: Context): PreDenotation =
       if (!classSymbol.hasChildren || (memberFingerPrint contains name)) {
diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala
index 27e177de6..14ebba57d 100644
--- a/src/dotty/tools/dotc/core/Types.scala
+++ b/src/dotty/tools/dotc/core/Types.scala
@@ -22,6 +22,7 @@ import transform.Erasure
 import printing.Printer
 import scala.util.hashing.{ MurmurHash3 => hashing }
 import collection.mutable
+import config.Config
 
 object Types {
 
@@ -416,7 +417,7 @@ object Types {
     final def member(name: Name)(implicit ctx: Context): Denotation = track("member-" + name) {
       try findMember(name, widenIfUnstable, EmptyFlags)
       catch {
-        case ex: Throwable => println(s"error occurred during: $this member $name"); throw ex // DEBUG
+        case ex: Throwable => println(s"error occurred during: $this: ${this.widen} member $name"); throw ex // DEBUG
       }
     }
 
@@ -572,10 +573,12 @@ object Types {
      *    - Or phase.erasedTypes is false and both types are neither method nor
      *      poly types.
      */
-    def matches(that: Type)(implicit ctx: Context): Boolean = track("matches") {
-      ctx.typeComparer.matchesType(
-        this, that, alwaysMatchSimple = !ctx.phase.erasedTypes)
-    }
+    def matches(that: Type)(implicit ctx: Context): Boolean =
+      if (Config.newMatch) this.signature == that.signature
+      else track("matches") {
+        ctx.typeComparer.matchesType(
+          this, that, alwaysMatchSimple = !ctx.phase.erasedTypes)
+      }
 
     /** The non-private symbol with given name in the given class that matches this type.
      *  @param inClass   The class containing the symbol's definition