Merge pull request #5454 from abeln/override-nullary

Fix #5453: method return type not checked when overriding nullary Java method

Author: Blaisorblade

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -868,7 +868,7 @@ object Types {
         matchLoosely && {
           val this1 = widenNullary(this)
           val that1 = widenNullary(that)
-          ((this1 `ne` this) || (that1 `ne` that)) && this1.overrides(this1, matchLoosely = false)
+          ((this1 `ne` this) || (that1 `ne` that)) && this1.overrides(that1, matchLoosely = false)
         }
       )
     }

tests/neg/i5453/J.java

@@ -0,0 +1,3 @@
+class J {
+	String foo() { return "hello"; }
+}

tests/neg/i5453/S.scala

@@ -0,0 +1,3 @@
+class S extends J {
+  override def foo(): Int = 42 // error: incompatible return type
+}