SI-7974 Avoid calling nonPrivateMember after erasure

One example were this would lead to subtle bugs otherwise is
Symbol_apply, where after erasure an overloaded symbol containing
Symbol#apply and UniquenessCache#apply is returned.

    // findMember considered harmful after erasure; e.g.
    //
    // scala> exitingErasure(Symbol_apply).isOverloaded
    // res27: Boolean = true

1 files changed, 12 insertions, 0 deletions

diff --git a/src/reflect/scala/reflect/internal/SymbolTable.scala b/src/reflect/scala/reflect/internal/SymbolTable.scala
index 0ce5a0fbea..c46a559d6d 100644
--- a/src/reflect/scala/reflect/internal/SymbolTable.scala
+++ b/src/reflect/scala/reflect/internal/SymbolTable.scala
@@ -244,6 +244,18 @@ abstract class SymbolTable extends macros.Universe
     finally popPhase(saved)
   }
 
+  final def findPhaseWithName(phaseName: String): Phase = {
+    var ph = phase
+    while (ph != NoPhase && ph.name != phaseName) {
+      ph = ph.prev
+    }
+    if (ph eq NoPhase) phase else ph
+  }
+  final def enteringPhaseWithName[T](phaseName: String)(body: => T): T = {
+    val phase = findPhaseWithName(phaseName)
+    enteringPhase(phase)(body)
+  }
+
   def slowButSafeEnteringPhase[T](ph: Phase)(op: => T): T = {
     if (isCompilerUniverse) enteringPhase(ph)(op)
     else op