Merge pull request scala#5279 from retronym/ticket/SD-183

SD-183 Make refinement classes ineligible as SAMs

Author: adriaanm

src/reflect/scala/reflect/internal/Definitions.scala

@@ -837,9 +837,9 @@ trait Definitions extends api.StandardDefinitions {
      * The class defining the method is a supertype of `tp` that
      * has a public no-arg primary constructor.
      */
-    def samOf(tp: Type): Symbol = if (!doSam) NoSymbol else {
+    def samOf(tp: Type): Symbol = if (!doSam) NoSymbol else if (!isNonRefinementClassType(unwrapToClass(tp))) NoSymbol else {
       // look at erased type because we (only) care about what ends up in bytecode
-      // (e.g., an alias type or intersection type is fine as long as the intersection dominator compiles to an interface)
+      // (e.g., an alias type is fine as long as is compiles to a single-abstract-method)
       val tpSym: Symbol = erasure.javaErasure(tp).typeSymbol
 
       if (tpSym.exists && tpSym.isClass

test/files/neg/sammy_restrictions.check

@@ -1,51 +1,62 @@
-sammy_restrictions.scala:35: error: type mismatch;
+sammy_restrictions.scala:38: error: type mismatch;
  found   : () => Int
  required: NoAbstract
   (() => 0)      : NoAbstract
       ^
-sammy_restrictions.scala:36: error: type mismatch;
+sammy_restrictions.scala:39: error: type mismatch;
  found   : Int => Int
  required: TwoAbstract
   ((x: Int) => 0): TwoAbstract
             ^
-sammy_restrictions.scala:37: error: type mismatch;
+sammy_restrictions.scala:40: error: type mismatch;
  found   : Int => Int
  required: NoEmptyConstructor
   ((x: Int) => 0): NoEmptyConstructor
             ^
-sammy_restrictions.scala:38: error: type mismatch;
+sammy_restrictions.scala:41: error: type mismatch;
  found   : Int => Int
  required: MultipleConstructorLists
   ((x: Int) => 0): MultipleConstructorLists
             ^
-sammy_restrictions.scala:39: error: type mismatch;
+sammy_restrictions.scala:42: error: type mismatch;
  found   : Int => Int
  required: OneEmptySecondaryConstructor
   ((x: Int) => 0): OneEmptySecondaryConstructor // derived class must have an empty *primary* to call.
             ^
-sammy_restrictions.scala:40: error: type mismatch;
+sammy_restrictions.scala:43: error: type mismatch;
  found   : Int => Int
  required: MultipleMethodLists
   ((x: Int) => 0): MultipleMethodLists
             ^
-sammy_restrictions.scala:41: error: type mismatch;
+sammy_restrictions.scala:44: error: type mismatch;
  found   : Int => Int
  required: ImplicitConstructorParam
   ((x: Int) => 0): ImplicitConstructorParam
             ^
-sammy_restrictions.scala:42: error: type mismatch;
+sammy_restrictions.scala:45: error: type mismatch;
  found   : Int => Int
  required: ImplicitMethodParam
   ((x: Int) => 0): ImplicitMethodParam
             ^
-sammy_restrictions.scala:43: error: type mismatch;
+sammy_restrictions.scala:46: error: type mismatch;
  found   : Int => Int
  required: PolyMethod
   ((x: Int) => 0): PolyMethod
             ^
-sammy_restrictions.scala:44: error: type mismatch;
+sammy_restrictions.scala:47: error: type mismatch;
  found   : Int => Int
  required: SelfTp
   ((x: Int) => 0): SelfTp
             ^
-10 errors found
+sammy_restrictions.scala:48: error: type mismatch;
+ found   : Int => Int
+ required: T1 with U1
+  ((x: Int) => 0): T1 with U1
+            ^
+sammy_restrictions.scala:49: error: type mismatch;
+ found   : Int => Int
+ required: Test.NonClassTypeRefinement
+    (which expands to)  DerivedOneAbstract with OneAbstract
+  ((x: Int) => 0): NonClassTypeRefinement
+            ^
+12 errors found

test/files/neg/sammy_restrictions.scala

@@ -27,9 +27,12 @@ abstract class DerivedOneAbstract extends OneAbstract
 abstract class SelfTp { self: NoAbstract => def ap(a: Int): Any }
 abstract class SelfVar { self => def ap(a: Int): Any }
 
+trait T1 { def t(a: Int): Int }; trait U1
+
 object Test {
   implicit val s: String = ""
-  type NonClassType = DerivedOneAbstract with OneAbstract
+  type NonClassTypeRefinement = DerivedOneAbstract with OneAbstract
+  type NonClassType = DerivedOneAbstract
 
   // errors:
   (() => 0)      : NoAbstract
@@ -42,6 +45,8 @@ object Test {
   ((x: Int) => 0): ImplicitMethodParam
   ((x: Int) => 0): PolyMethod
   ((x: Int) => 0): SelfTp
+  ((x: Int) => 0): T1 with U1
+  ((x: Int) => 0): NonClassTypeRefinement
 
   // allowed:
   ((x: Int) => 0): OneEmptyConstructor