Don't check bounds for type definitions in abstract classes

Don't check bounds for type definitions in abstract classes, traits, or refinements.
Bounds violations will be detected when values of these types are created.

Author: odersky

compiler/src/dotty/tools/dotc/transform/PostTyper.scala

@@ -399,7 +399,7 @@ class PostTyper extends MacroTransform with IdentityDenotTransformer { thisPhase
               val relativePath = util.SourceFile.relativePath(ctx.compilationUnit.source, reference)
               sym.addAnnotation(Annotation.makeSourceFile(relativePath))
           else
-            if !sym.is(Param) then
+            if !sym.is(Param) && !sym.owner.isOneOf(AbstractOrTrait) then
               Checking.checkGoodBounds(tree.symbol)
             (tree.rhs, sym.info) match
               case (rhs: LambdaTypeTree, bounds: TypeBounds) =>

tests/neg/i11572.scala renamed to tests/init/neg/i11572.scala

@@ -5,7 +5,7 @@ class A {
   trait Bounded {
     type T >: Cov[Int] <: Cov[String] // error
   }
-  val t: Bounded = new Bounded {
+  val t: Bounded = new Bounded {  // error
     // Note: using this instead of t produces an error (as expected)
     override type T >: t.T <: t.T
   }

tests/neg/i5854.scala renamed to tests/init/neg/i5854.scala

@@ -100,7 +100,7 @@ object Indirect {
   trait U {
     trait X {
       val q: A & B = ???
-      type M = q.L // error: conflicting bounds
+      type M = q.L
     }
     final lazy val p: X = ???
     def brand(x: Any): p.M = x // error: conflicting bounds
@@ -119,7 +119,7 @@ object Indirect2 {
     }
     trait X {
       val q: Y = ???
-      type M = q.r.L  // error: conflicting bounds
+      type M = q.r.L
     }
     final lazy val p: X = ???
     def brand(x: Any): p.M = x // error: conflicting bounds
@@ -152,7 +152,7 @@ object Rec2 {
     }
     trait X {
       val q: Y = ???
-      type M = q.r.L // error: conflicting bounds
+      type M = q.r.L
     }
     final lazy val p: X = ???
     def brand(x: Any): p.M = x // error: conflicting bounds
@@ -171,7 +171,7 @@ object Indirect3 {
     }
     trait X {
       val q: Y = ???
-      type M = q.r.L // error: conflicting bounds
+      type M = q.r.L
     }
     final lazy val p: X = ???
     def brand(x: Any): p.M = x // error: conflicting bounds

tests/neg-strict/i1050.scala

@@ -1,11 +1,7 @@
 package i5854
 
 class B/*<-i5854::B#*/ {
-  // Known issue: Can't lookup the symbol of `b.A`
-  // we have to register the symbol of `b { type A }` to the refinementSymtab first
-  // then resolve, or assign same semanticdb symbol for both
-  // fake symbol for b.A, and real symbol of A in b
   val a/*<-i5854::B#a.*/: String/*->scala::Predef.String#*/ = (((1: Any/*->scala::Any#*/): b/*->i5854::B#b.*/.A): Nothing/*->scala::Nothing#*/): String/*->scala::Predef.String#*/
-  val b/*<-i5854::B#b.*/: { type A/*<-local0*/ >: Any/*->scala::Any#*/ <: Nothing/*->scala::Nothing#*/ } = loop/*->i5854::B#loop().*/()         // error
+  val b/*<-i5854::B#b.*/: { type A/*<-local0*/ >: Any/*->scala::Any#*/ <: Nothing/*->scala::Nothing#*/ } = loop/*->i5854::B#loop().*/() // error
   def loop/*<-i5854::B#loop().*/(): Nothing/*->scala::Nothing#*/ = loop/*->i5854::B#loop().*/()
 }

tests/semanticdb/expect/i5854.expect.scala

@@ -0,0 +1,7 @@
+package i5854
+
+class B {
+  val a: String = (((1: Any): b.A): Nothing): String
+  val b: { type A >: Any <: Nothing } = loop() // error
+  def loop(): Nothing = loop()
+}

tests/semanticdb/expect/i5854.scala

@@ -3923,6 +3923,43 @@ Occurrences:
 [0:8..0:15): example <- example/
 [2:6..2:24): FilenameWithSpaces <- example/FilenameWithSpaces#
 
+expect/i5854.scala
+------------------
+
+Summary:
+Schema => SemanticDB v4
+Uri => i5854.scala
+Text => empty
+Language => Scala
+Symbols => 6 entries
+Occurrences => 16 entries
+
+Symbols:
+i5854/B# => class B extends Object { self: B => +4 decls }
+i5854/B#`<init>`(). => primary ctor <init> (): B
+i5854/B#a. => val method a String
+i5854/B#b. => val method b Object { type A  >: Any <: Nothing }
+i5854/B#loop(). => method loop (): Nothing
+local0 => type A  >: Any <: Nothing
+
+Occurrences:
+[0:8..0:13): i5854 <- i5854/
+[2:6..2:7): B <- i5854/B#
+[3:6..3:7): a <- i5854/B#a.
+[3:9..3:15): String -> scala/Predef.String#
+[3:24..3:27): Any -> scala/Any#
+[3:30..3:31): b -> i5854/B#b.
+[3:36..3:43): Nothing -> scala/Nothing#
+[3:46..3:52): String -> scala/Predef.String#
+[4:6..4:7): b <- i5854/B#b.
+[4:16..4:17): A <- local0
+[4:21..4:24): Any -> scala/Any#
+[4:28..4:35): Nothing -> scala/Nothing#
+[4:40..4:44): loop -> i5854/B#loop().
+[5:6..5:10): loop <- i5854/B#loop().
+[5:14..5:21): Nothing -> scala/Nothing#
+[5:24..5:28): loop -> i5854/B#loop().
+
 expect/i9727.scala
 ------------------