backport of 25800,25801

Author: Antonio Cunei

src/compiler/scala/tools/nsc/interactive/CompilerControl.scala

@@ -187,11 +187,12 @@ trait CompilerControl { self: Global =>
   /** If source if not yet loaded, get an outline view with askParseEntered.
    *  If source is loaded, wait for it to be typechecked.
    *  In both cases, set response to parsed (and possibly typechecked) tree.
+   *  @param keepSrcLoaded If set to `true`, source file will be kept as a loaded unit afterwards.
    */
-  def askStructure(source: SourceFile, response: Response[Tree]) = {
+  def askStructure(keepSrcLoaded: Boolean)(source: SourceFile, response: Response[Tree]) = {
     getUnit(source) match {
       case Some(_) => askLoadedTyped(source, response)
-      case None => askParsedEntered(source, false, response)
+      case None => askParsedEntered(source, keepSrcLoaded, response)
     }
   }
 

src/compiler/scala/tools/nsc/symtab/Symbols.scala

@@ -2056,11 +2056,13 @@ trait Symbols extends reflect.generic.Symbols { self: SymbolTable =>
     }
     override def sourceModule = module
     private var implicitMembersCacheValue: List[Symbol] = List()
-    private var implicitMembersCacheKey: Type = NoType
+    private var implicitMembersCacheKey1: Type = NoType
+    private var implicitMembersCacheKey2: ScopeEntry = null
     def implicitMembers: List[Symbol] = {
       val tp = info
-      if (implicitMembersCacheKey ne tp) {
-        implicitMembersCacheKey = tp
+      if ((implicitMembersCacheKey1 ne tp) || (implicitMembersCacheKey2 ne tp.decls.elems)) {
+        implicitMembersCacheKey1 = tp
+        implicitMembersCacheKey2 = tp.decls.elems
         implicitMembersCacheValue = tp.implicitMembers
       }
       implicitMembersCacheValue