SI-10260 better error messages for raw Java types

src/compiler/scala/tools/nsc/typechecker/RefChecks.scala

@@ -704,7 +704,7 @@ abstract class RefChecks extends Transform {
                           // Compilation has already failed so we shouldn't have to worry overmuch
                           // about forcing types.
                           if (underlying.isJavaDefined && pa.typeArgs.isEmpty && abstractSym.typeParams.nonEmpty)
-                            ". To implement a raw type, use %s[_]".format(pa)
+                            s". To implement this raw type, use ${rawToExistential(pa)}"
                           else if (pa.prefix =:= pc.prefix)
                             ": their type parameters differ"
                           else

src/reflect/scala/reflect/internal/Types.scala

@@ -3876,8 +3876,8 @@ trait Types
   }
 
   def typeParamsToExistentials(clazz: Symbol, tparams: List[Symbol]): List[Symbol] = {
-    val eparams = mapWithIndex(tparams)((tparam, i) =>
-      clazz.newExistential(newTypeName("?"+i), clazz.pos) setInfo tparam.info.bounds)
+    val eparams = tparams map (tparam =>
+      clazz.newExistential(tparam.name.toTypeName, clazz.pos) setInfo tparam.info.bounds)
 
     eparams map (_ substInfo (tparams, eparams))
   }

test/files/neg/abstract-class-error.check

@@ -1,5 +1,5 @@
 S.scala:1: error: class S needs to be abstract, since method g in class J of type (y: Int, z: java.util.List)Int is not defined
-(Note that java.util.List does not match java.util.List[String]. To implement a raw type, use java.util.List[_])
+(Note that java.util.List does not match java.util.List[String]. To implement this raw type, use java.util.List[_])
 class S extends J {
       ^
 one error found

test/files/neg/t10260.check

@@ -0,0 +1,17 @@
+Test.scala:1: error: class IAImpl needs to be abstract, since method foo in trait IA of type (a: A)Unit is not defined
+(Note that A does not match A[_]. To implement this raw type, use A[T] forSome { type T <: A[T] })
+class IAImpl extends IA { def foo(a: A[_]) = ??? }
+      ^
+Test.scala:2: error: class IBImpl needs to be abstract, since method foo in trait IB of type (a: B)Unit is not defined
+(Note that B does not match B[_, _]. To implement this raw type, use B[T,R] forSome { type T; type R <: java.util.List[_ >: T] })
+class IBImpl extends IB { def foo(a: B[_,_]) = ??? }
+      ^
+Test.scala:3: error: class ICImpl needs to be abstract, since method foo in trait IC of type (a: Int, b: C, c: String)C is not defined
+(Note that C does not match C[_]. To implement this raw type, use C[_ <: String])
+class ICImpl extends IC { def foo(a: Int, b: C[_], c: String) = ??? }
+      ^
+Test.scala:4: error: class IDImpl needs to be abstract, since method foo in trait ID of type (a: D)Unit is not defined
+(Note that D does not match D[_ <: String]. To implement this raw type, use D[_])
+class IDImpl extends ID { def foo(a: D[_ <: String]) = ??? }
+      ^
+four errors found

test/files/neg/t10260/A.java

@@ -0,0 +1,2 @@
+public class A<T extends A<T>> {}
+

test/files/neg/t10260/B.java

@@ -0,0 +1,2 @@
+public class B<T, R extends java.util.List<? super T>> {}
+

test/files/neg/t10260/C.java

@@ -0,0 +1,2 @@
+public class C<T extends String> {}
+

test/files/neg/t10260/D.java

@@ -0,0 +1,2 @@
+public class D<T> {}
+

test/files/neg/t10260/IA.java

@@ -0,0 +1,3 @@
+public interface IA {
+    void foo(A a);
+}

test/files/neg/t10260/IB.java

@@ -0,0 +1,3 @@
+public interface IB {
+    void foo(B a);
+}

test/files/neg/t10260/IC.java

@@ -0,0 +1,3 @@
+public interface IC {
+    C foo(int a, C b, String c);
+}

test/files/neg/t10260/ID.java

@@ -0,0 +1,3 @@
+public interface ID {
+    void foo(D a);
+}

test/files/neg/t10260/Test.scala

@@ -0,0 +1,4 @@
+class IAImpl extends IA { def foo(a: A[_]) = ??? }
+class IBImpl extends IB { def foo(a: B[_,_]) = ??? }
+class ICImpl extends IC { def foo(a: Int, b: C[_], c: String) = ??? }
+class IDImpl extends ID { def foo(a: D[_ <: String]) = ??? }

test/files/neg/t8244.check

@@ -1,4 +1,4 @@
-Test_2.scala:9: error: value exxx is not a member of ?0
+Test_2.scala:9: error: value exxx is not a member of T
     raw.t.exxx // java.lang.ClassCastException: java.lang.String cannot be cast to X
           ^
 one error found

test/files/neg/t8244e.check

@@ -1,4 +1,4 @@
-Test.scala:9: error: value exxx is not a member of ?0
+Test.scala:9: error: value exxx is not a member of T
     raw.t.exxx // java.lang.ClassCastException: java.lang.String cannot be cast to X
           ^
 one error found

test/files/run/existentials-in-compiler.check

@@ -2,16 +2,16 @@ abstract trait Bippy[A <: AnyRef, B] extends AnyRef
     extest.Bippy[_ <: AnyRef, _]
 
 abstract trait BippyBud[A <: AnyRef, B, C <: List[A]] extends AnyRef
-    extest.BippyBud[?0,?1,?2] forSome { type ?0 <: AnyRef; type ?1; type ?2 <: List[?0] }
+    extest.BippyBud[A,B,C] forSome { type A <: AnyRef; type B; type C <: List[A] }
 
 abstract trait BippyLike[A <: AnyRef, B <: List[A], This <: extest.BippyLike[A,B,This] with extest.Bippy[A,B]] extends AnyRef
-    extest.BippyLike[?0,?1,?2] forSome { type ?0 <: AnyRef; type ?1 <: List[?0]; type ?2 <: extest.BippyLike[?0,?1,?2] with extest.Bippy[?0,?1] }
+    extest.BippyLike[A,B,This] forSome { type A <: AnyRef; type B <: List[A]; type This <: extest.BippyLike[A,B,This] with extest.Bippy[A,B] }
 
 abstract trait Contra[-A >: AnyRef, -B] extends AnyRef
     extest.Contra[_ >: AnyRef, _]
 
 abstract trait ContraLike[-A >: AnyRef, -B >: List[A]] extends AnyRef
-    extest.ContraLike[?0,?1] forSome { type ?0 >: AnyRef; type ?1 >: List[?0] }
+    extest.ContraLike[A,B] forSome { type A >: AnyRef; type B >: List[A] }
 
 abstract trait Cov01[+A <: AnyRef, +B] extends AnyRef
     extest.Cov01[_ <: AnyRef, _]
@@ -95,28 +95,28 @@ abstract trait Cov29[-A, -B] extends AnyRef
     extest.Cov29[_, _]
 
 abstract trait Cov31[+A, +B, C <: (A, B)] extends AnyRef
-    extest.Cov31[?0,?1,?2] forSome { type ?0; type ?1; type ?2 <: (?0, ?1) }
+    extest.Cov31[A,B,C] forSome { type A; type B; type C <: (A, B) }
 
 abstract trait Cov32[+A, B, C <: (A, B)] extends AnyRef
-    extest.Cov32[?0,?1,?2] forSome { type ?0; type ?1; type ?2 <: (?0, ?1) }
+    extest.Cov32[A,B,C] forSome { type A; type B; type C <: (A, B) }
 
 abstract trait Cov33[+A, -B, C <: Tuple2[A, _]] extends AnyRef
-    extest.Cov33[?0,?1,?2] forSome { type ?0; type ?1; type ?2 <: Tuple2[?0, _] }
+    extest.Cov33[A,B,C] forSome { type A; type B; type C <: Tuple2[A, _] }
 
 abstract trait Cov34[A, +B, C <: (A, B)] extends AnyRef
-    extest.Cov34[?0,?1,?2] forSome { type ?0; type ?1; type ?2 <: (?0, ?1) }
+    extest.Cov34[A,B,C] forSome { type A; type B; type C <: (A, B) }
 
 abstract trait Cov35[A, B, C <: (A, B)] extends AnyRef
-    extest.Cov35[?0,?1,?2] forSome { type ?0; type ?1; type ?2 <: (?0, ?1) }
+    extest.Cov35[A,B,C] forSome { type A; type B; type C <: (A, B) }
 
 abstract trait Cov36[A, -B, C <: Tuple2[A, _]] extends AnyRef
-    extest.Cov36[?0,?1,?2] forSome { type ?0; type ?1; type ?2 <: Tuple2[?0, _] }
+    extest.Cov36[A,B,C] forSome { type A; type B; type C <: Tuple2[A, _] }
 
 abstract trait Cov37[-A, +B, C <: Tuple2[_, B]] extends AnyRef
-    extest.Cov37[?0,?1,?2] forSome { type ?0; type ?1; type ?2 <: Tuple2[_, ?1] }
+    extest.Cov37[A,B,C] forSome { type A; type B; type C <: Tuple2[_, B] }
 
 abstract trait Cov38[-A, B, C <: Tuple2[_, B]] extends AnyRef
-    extest.Cov38[?0,?1,?2] forSome { type ?0; type ?1; type ?2 <: Tuple2[_, ?1] }
+    extest.Cov38[A,B,C] forSome { type A; type B; type C <: Tuple2[_, B] }
 
 abstract trait Cov39[-A, -B, C <: Tuple2[_, _]] extends AnyRef
     extest.Cov39[_, _, _ <: Tuple2[_, _]]
@@ -152,5 +152,5 @@ abstract trait Covariant[+A <: AnyRef, +B] extends AnyRef
     extest.Covariant[_ <: AnyRef, _]
 
 abstract trait CovariantLike[+A <: AnyRef, +B <: List[A], +This <: extest.CovariantLike[A,B,This] with extest.Covariant[A,B]] extends AnyRef
-    extest.CovariantLike[?0,?1,?2] forSome { type ?0 <: AnyRef; type ?1 <: List[?0]; type ?2 <: extest.CovariantLike[?0,?1,?2] with extest.Covariant[?0,?1] }
+    extest.CovariantLike[A,B,This] forSome { type A <: AnyRef; type B <: List[A]; type This <: extest.CovariantLike[A,B,This] with extest.Covariant[A,B] }
 

test/files/run/t5418b.check

@@ -1,2 +1,2 @@
 new Object().getClass()
-TypeRef(ThisType(java.lang), java.lang.Class, List(TypeRef(NoPrefix, TypeName("?0"), List())))
+TypeRef(ThisType(java.lang), java.lang.Class, List(TypeRef(NoPrefix, TypeName("T"), List())))