Fix test("capture value in closure")

[froth]

The test broke with the update of scala 3.3.0 (#1225). However the old while loop used in the test as verification did not capture the var so always created List(3,3,3). So it tested that the implementation is actually wrong. I changed the test to now use a fixed List.

fixes #1225

[froth]

This includes an update of the scala 3 version.

Therefore it supersedes #1249

[froth]

OK, this however fails as the scala2 macros still behave the same as before (which means "not correct" in my opinion).
I quickly tried

diff --git a/macros/src/main/scala-2/spire/macros/Syntax.scala b/macros/src/main/scala-2/spire/macros/Syntax.scala
index c765a8e4..d2a814b5 100644
--- a/macros/src/main/scala-2/spire/macros/Syntax.scala
+++ b/macros/src/main/scala-2/spire/macros/Syntax.scala
@@ -190,7 +190,8 @@ object Syntax {
       q"""
       var $index = $init
       while ($test($index)) {
-        $body($index)
+        val indexCopy = $index
+        $body(indexCopy)
         $index = $next($index)
       }
       """

which actually fixes the test. However this breaks spire.syntax.CforSuite.nested cfor.

Maybe someone more experienced in the cfor macro (or scala 2 macros in general) can have a look and give me a hint.

[armanbilge]

OK, this however fails as the scala2 macros still behave the same as before (which means "not correct" in my opinion).

Whether it is "not correct" or not in any of our opinions doesn't really matter unfortunately 😕 at this point, we shouldn't really be changing the behavior of cfor. Even more so, we shouldn't be changing the behavior of something for which a test was explicitly added asserting what the intended behavior is.

[froth]

I get you point. Does not make me happy but makes sense. I will leave it at that.

For anybody picking this up in the future:

This is the decompiled output of the relevant part of the test under scala 3.2.2(working test):

      ArrayBuffer b1 = scala.collection.mutable.ArrayBuffer..MODULE$.empty();

      int var3;
      for(IntRef index = IntRef.create(0); index.elem < 3; index.elem = var3) {
         b1.$plus$eq(() -> {
            return index.elem;
         });
         var3 = index.elem + 1;
      }

And under 3.3.0(broken tests):

      ArrayBuffer b1 = scala.collection.mutable.ArrayBuffer..MODULE$.empty();

      for(int index = 0; index < 3; ++index) {
         b1.$plus$eq(() -> {
            return index;
         });
      }

[mio-19]

Is the intended behavior used in real code? If not, is introducing a breaking change an option?