Fix and document for-each loops

CHANGELOG.md

@@ -66,6 +66,8 @@
 
 * Fixed `@long` and `@long_be` array filters.
 
+* Fixed for-each loops with non-constant arrays.
+
 * 8080 and LR35902: fixed large stack variables.
 
 * Other bug fixes.

docs/lang/syntax.md

@@ -312,11 +312,13 @@ for <variable> : [ <comma separated expressions> ]  {
     
     * `paralleluntil` – the same as `until`, but the iterations may be executed in any order
     
-    There is no `paralleldownto`, because it would do the same as `parallelto`.
+    There is no `paralleldownto`, because it would do the same as `parallelto` with swapped arguments.
 
 * `<enum type>` – traverse enum constants of given type, in arbitrary order
 
-* `<comma separated expressions>` – traverse every value in the list
+* `<comma separated expressions>` – traverse every value in the list, in the given order.
+Values do not have to be constant.
+If a value is not a constant and its value changes while executing the loop, the behaviour is undefined.
 
 ### `break` and `continue` statements
 

src/main/scala/millfork/node/Node.scala

@@ -515,7 +515,7 @@ case class ForStatement(variable: String, start: Expression, end: Expression, di
 }
 
 case class ForEachStatement(variable: String, values: Either[Expression, List[Expression]], body: List[ExecutableStatement]) extends CompoundStatement {
-  override def getAllExpressions: List[Expression] = VariableExpression(variable) :: body.flatMap(_.getAllExpressions)
+  override def getAllExpressions: List[Expression] = VariableExpression(variable) :: (values.fold[List[Expression]](_ => Nil, identity) ++ body.flatMap(_.getAllExpressions))
 
   override def getChildStatements: Seq[Statement] = body
   override def flatMap(f: ExecutableStatement => Option[ExecutableStatement]): Option[ExecutableStatement] = {

src/test/scala/millfork/test/ForLoopSuite.scala

@@ -351,7 +351,9 @@ class ForLoopSuite extends FunSuite with Matchers {
         |   for p:[$c000, $c003, $c005, $c007]{
         |     p[0] = 34
         |   }
-        |   for p:[$c001, $c004, $c006, $c008]{
+        |   word w
+        |   w = $c004
+        |   for p:[$c001, w, $c006, w+4]{
         |     p[0] = 42
         |   }
         | }