First pass at using a compiler plugin to remove the need for the `override` keyword when overriding a field within a `mill.Module`

This only applies to `mill.Module`s, not overrides elsewhere which still require the keyword. `mill.Module`s tend to have lots and lots of overriding, so the keyword is basically noise.

Also includes the necessary build changes to enable the locally-built Scalac plugin when compiling the test suite. Note that no changes are necessary for the executable assembly, because the `scalac-plugin.xml` will be included in the assembly and get picked up by the Ammonite scalac plugin classloader automatically

1 files changed, 14 insertions, 1 deletions

diff --git a/core/src/test/scala/mill/define/CacherTests.scala b/core/src/test/scala/mill/define/CacherTests.scala
index bacfa598..4b8e31ab 100644
--- a/core/src/test/scala/mill/define/CacherTests.scala
+++ b/core/src/test/scala/mill/define/CacherTests.scala
@@ -14,7 +14,7 @@ object CacherTests extends TestSuite{
   }
   object Middle extends Middle
   trait Middle extends Base{
-    override def value = T{ super.value() + 2}
+    def value = T{ super.value() + 2}
     def overriden = T{ super.value()}
   }
   object Terminal extends Terminal
@@ -49,6 +49,19 @@ object CacherTests extends TestSuite{
       eval(Terminal, Terminal.value) == 7,
       eval(Terminal, Terminal.overriden) == 1
     )
+    //    Doesn't fail, presumably compileError doesn't go far enough in the
+    //    compilation pipeline to hit the override checks
+    //
+    //    'overrideOutsideModuleFails - {
+    //      compileError("""
+    //        trait Foo{
+    //          def x = 1
+    //        }
+    //        object Bar extends Foo{
+    //          def x = 2
+    //        }
+    //      """)
+    //    }
   }
 }