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-rw-r--r--src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala58
1 files changed, 41 insertions, 17 deletions
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala b/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
index 814c78b69c..b4f091b37f 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
@@ -562,38 +562,62 @@ class Inliner[BT <: BTypes](val btypes: BT) {
* @param memberDeclClass The class in which the member is declared (A)
* @param memberRefClass The class used in the member reference (B)
*
+ * (B0) JVMS 5.4.3.2 / 5.4.3.3: when resolving a member of class C in D, the class C is resolved
+ * first. According to 5.4.3.1, this requires C to be accessible in D.
+ *
* JVMS 5.4.4 summary: A field or method R is accessible to a class D (destinationClass) iff
* (B1) R is public
* (B2) R is protected, declared in C (memberDeclClass) and D is a subclass of C.
* If R is not static, R must contain a symbolic reference to a class T (memberRefClass),
* such that T is either a subclass of D, a superclass of D, or D itself.
+ * Also (P) needs to be satisfied.
* (B3) R is either protected or has default access and declared by a class in the same
* run-time package as D.
+ * If R is protected, also (P) needs to be satisfied.
* (B4) R is private and is declared in D.
+ *
+ * (P) When accessing a protected instance member, the target object on the stack (the receiver)
+ * has to be a subtype of D (destinationClass). This is enforced by classfile verification
+ * (https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.10.1.8).
+ *
+ * TODO: we cannot currently implement (P) because we don't have the necessary information
+ * available. Once we have a type propagation analysis implemented, we can extract the receiver
+ * type from there (https://github.com/scala-opt/scala/issues/13).
*/
def memberIsAccessible(memberFlags: Int, memberDeclClass: ClassBType, memberRefClass: ClassBType): Either[OptimizerWarning, Boolean] = {
// TODO: B3 requires "same run-time package", which seems to be package + classloader (JMVS 5.3.). is the below ok?
def samePackageAsDestination = memberDeclClass.packageInternalName == destinationClass.packageInternalName
-
- val key = (ACC_PUBLIC | ACC_PROTECTED | ACC_PRIVATE) & memberFlags
- key match {
- case ACC_PUBLIC => // B1
- Right(true)
-
- case ACC_PROTECTED => // B2
- tryEither {
- val condB2 = destinationClass.isSubtypeOf(memberDeclClass).orThrow && {
- val isStatic = (ACC_STATIC & memberFlags) != 0
- isStatic || memberRefClass.isSubtypeOf(destinationClass).orThrow || destinationClass.isSubtypeOf(memberRefClass).orThrow
+ def targetObjectConformsToDestinationClass = false // needs type propagation analysis, see above
+
+ def memberIsAccessibleImpl = {
+ val key = (ACC_PUBLIC | ACC_PROTECTED | ACC_PRIVATE) & memberFlags
+ key match {
+ case ACC_PUBLIC => // B1
+ Right(true)
+
+ case ACC_PROTECTED => // B2
+ val isStatic = (ACC_STATIC & memberFlags) != 0
+ tryEither {
+ val condB2 = destinationClass.isSubtypeOf(memberDeclClass).orThrow && {
+ isStatic || memberRefClass.isSubtypeOf(destinationClass).orThrow || destinationClass.isSubtypeOf(memberRefClass).orThrow
+ }
+ Right(
+ (condB2 || samePackageAsDestination /* B3 (protected) */) &&
+ (isStatic || targetObjectConformsToDestinationClass) // (P)
+ )
}
- Right(condB2 || samePackageAsDestination) // B3 (protected)
- }
- case 0 => // B3 (default access)
- Right(samePackageAsDestination)
+ case 0 => // B3 (default access)
+ Right(samePackageAsDestination)
+
+ case ACC_PRIVATE => // B4
+ Right(memberDeclClass == destinationClass)
+ }
+ }
- case ACC_PRIVATE => // B4
- Right(memberDeclClass == destinationClass)
+ classIsAccessible(memberDeclClass) match { // B0
+ case Right(true) => memberIsAccessibleImpl
+ case r => r
}
}