SI-6733 LOCAL, isLocal, and private[this]

Due to an unfortunate name collision, internal.Symbols#Symbol.isLocal
means something different from Flag.LOCAL. Therefore api.Symbols#Symbol.isLocal
was directly violating its documentation.

Since we can’t give api#isLocal an implementation different from internal#isLocal,
we have to rename, and for that occasion I have come up with names
api#isPrivateThis and api#isProtectedThis, which in my opinion suits the
public API better than internal#isPrivateLocal and internal#isProtectedLocal.

Given the extraordinary circumstances of having no way for api#isLocal
to work correctly, I’m forced to remove api#isLocal without a deprecation
notice, exercising our right to break experimental APIs, something that
we have never done before for reflection or macros. This is sad.

3 files changed, 17 insertions, 10 deletions

diff --git a/src/reflect/scala/reflect/api/FlagSets.scala b/src/reflect/scala/reflect/api/FlagSets.scala
index 44c5f78a48..f36056cc3b 100644
--- a/src/reflect/scala/reflect/api/FlagSets.scala
+++ b/src/reflect/scala/reflect/api/FlagSets.scala
@@ -131,8 +131,8 @@ trait FlagSets { self: Universe =>
     /** Flag indicating that tree has `protected` modifier set */
     val PROTECTED: FlagSet
 
-    /** Flag indicating that tree represents a member local to current class
-     *  (i.e. private[this] or protected[this].
+    /** Flag indicating that tree represents a member local to current class,
+     *  i.e. private[this] or protected[this].
      *  This requires having either PRIVATE or PROTECTED set as well.
      */
     val LOCAL: FlagSet
diff --git a/src/reflect/scala/reflect/api/Symbols.scala b/src/reflect/scala/reflect/api/Symbols.scala
index 1c3ae77d45..15d4fae59b 100644
--- a/src/reflect/scala/reflect/api/Symbols.scala
+++ b/src/reflect/scala/reflect/api/Symbols.scala
@@ -380,16 +380,13 @@ trait Symbols { self: Universe =>
      */
     def isImplementationArtifact: Boolean
 
-    /** Does this symbol represent a local declaration or definition?
-     *
-     *  If yes, either `isPrivate` or `isProtected` are guaranteed to be true.
-     *  Local symbols can only be accessed from the same object instance.
-     *
-     *  If yes, `privateWithin` might tell more about this symbol's visibility scope.
+    /** Does this symbol represent a declaration or definition written in a source file as `private[this]`
+     *  or generated in tree/symbol form with the combination of flags LOCAL and PRIVATE?
+     *  If yes, `isPrivate` is guaranteed to be true,
      *
      *  @group Tests
      */
-    def isLocal: Boolean
+    def isPrivateThis: Boolean
 
     /** Does this symbol represent a private declaration or definition?
      *  If yes, `privateWithin` might tell more about this symbol's visibility scope.
@@ -398,6 +395,14 @@ trait Symbols { self: Universe =>
      */
     def isPrivate: Boolean
 
+    /** Does this symbol represent a declaration or definition written in a source file as `protected[this]`
+     *  or generated in tree/symbol form with the combination of flags LOCAL and PROTECTED?
+     *  If yes, `isProtected` is guaranteed to be true,
+     *
+     *  @group Tests
+     */
+    def isProtectedThis: Boolean
+
     /** Does this symbol represent a protected declaration or definition?
      *  If yes, `privateWithin` might tell more about this symbol's visibility scope.
      *
@@ -412,7 +417,7 @@ trait Symbols { self: Universe =>
     def isPublic: Boolean
 
     /**
-     * Set when symbol has a modifier of the form private[X], NoSymbol otherwise.
+     *  Set when symbol has a modifier of the form private[X] or protected[X], NoSymbol otherwise.
      *
      *  Access level encoding: there are three scala flags (PRIVATE, PROTECTED,
      *  and LOCAL) which combine with value privateWithin (the "foo" in private[foo])
diff --git a/src/reflect/scala/reflect/internal/Symbols.scala b/src/reflect/scala/reflect/internal/Symbols.scala
index 593c5e314a..6fedb74f86 100644
--- a/src/reflect/scala/reflect/internal/Symbols.scala
+++ b/src/reflect/scala/reflect/internal/Symbols.scala
@@ -90,6 +90,8 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     def isVal: Boolean = isTerm && !isModule && !isMethod && !isMutable
     def isVar: Boolean = isTerm && !isModule && !isMethod && !isLazy && isMutable
     def isAbstract: Boolean = isAbstractClass || isDeferred || isAbstractType
+    def isPrivateThis = (this hasFlag PRIVATE) && (this hasFlag LOCAL)
+    def isProtectedThis = (this hasFlag PROTECTED) && (this hasFlag LOCAL)
 
     def newNestedSymbol(name: Name, pos: Position, newFlags: Long, isClass: Boolean): Symbol = name match {
       case n: TermName => newTermSymbol(n, pos, newFlags)