First pass at providing good compile errors to invalid uses of the `T{...}` macro: we should only allow you to `Target#apply()` on expressions whose values come from outside the `T{...}` block

1 files changed, 33 insertions, 2 deletions

diff --git a/core/src/test/scala/forge/CacherTests.scala b/core/src/test/scala/forge/CacherTests.scala
index de8265bd..d77287ac 100644
--- a/core/src/test/scala/forge/CacherTests.scala
+++ b/core/src/test/scala/forge/CacherTests.scala
@@ -50,8 +50,39 @@ object CacherTests extends TestSuite{
       val expectedMsg =
         "T{} members defined in a Cacher class/trait/object body must be defs"
 
-      val err1 = compileError("object Foo extends Target.Cacher{ val x = T{1} }")
-      assert(err1.msg == expectedMsg)
+      val err = compileError("object Foo extends Target.Cacher{ val x = T{1} }")
+      assert(err.msg == expectedMsg)
+    }
+    'badTmacro - {
+      // Make sure we can reference values from outside the T{...} block as part
+      // of our `Target#apply()` calls, but we cannot reference any values that
+      // come from inside the T{...} block
+      'pos - {
+        val a = T{ 1 }
+        val arr = Array(a)
+        val b = {
+          val c = 0
+          T{
+            arr(c)()
+          }
+        }
+      }
+      'neg - {
+
+        val expectedMsg =
+          "Target#apply() call cannot use `value n` defined within the T{...} block"
+        val err = compileError("""{
+          val a = T{ 1 }
+          val arr = Array(a)
+          val b = {
+            T{
+              val n = 0
+              arr(n)()
+            }
+          }
+        }""")
+        assert(err.msg == expectedMsg)
+      }
     }
   }
 }