empty for loops are removed

compiler/src/prog8/ast/processing/AstChecker.kt

@@ -110,9 +110,6 @@ internal class AstChecker(private val program: Program,
     }
 
     override fun visit(forLoop: ForLoop) {
-        if(forLoop.body.containsNoCodeNorVars())
-            errors.warn("for loop body is empty", forLoop.position)
-
         val iterableDt = forLoop.iterable.inferType(program).typeOrElse(DataType.BYTE)
         if(iterableDt !in IterableDatatypes && forLoop.iterable !is RangeExpr) {
             errors.err("can only loop over an iterable type", forLoop.position)

compiler/src/prog8/optimizer/StatementOptimizer.kt

@@ -195,7 +195,7 @@ internal class StatementOptimizer(private val program: Program,
 
     override fun after(forLoop: ForLoop, parent: Node): Iterable<IAstModification> {
         if(forLoop.body.containsNoCodeNorVars()) {
-            // remove empty for loop
+            errors.warn("removing empty for loop", forLoop.position)
             return listOf(IAstModification.Remove(forLoop, parent))
         } else if(forLoop.body.statements.size==1) {
             val loopvar = forLoop.body.statements[0] as? VarDecl

examples/bdmusic.p8

@@ -37,10 +37,8 @@ sub start() {
 }
 
 sub delay() {
-    ubyte d
-    for d in 0 to 12 {
-        while c64.RASTER!=0 {
-            ; tempo delay synced to screen refresh
+    repeat 32 {
+        while c64.RASTER {
         }
     }
 }

examples/fibonacci.p8

@@ -7,8 +7,7 @@ main {
     sub start() {
         c64scr.print("fibonacci sequence\n")
 
-        ubyte i
-        for i in 0 to 20 {
+        repeat 21 {
             c64scr.print_uw(fib_next())
             c64.CHROUT('\n')
         }

examples/test.p8

@@ -7,64 +7,7 @@
 
 main {
 
-    ; TODO check removal of empty loops
-
-
-
     sub start() {
-        ubyte i
-        for i in 1 to 20 {
-            c64.CHROUT('*')
-        }
-        c64.CHROUT('\n')
-
-        i=0
-        do {
-            c64.CHROUT('*')
-            i++
-        } until i==20
-        c64.CHROUT('\n')
-
-        repeat {
-            break
-            continue
-            c64.CHROUT('*')
-        }
-        c64.CHROUT('\n')
-
-        repeat 0 {
-            c64.CHROUT('@')
-            break
-            continue
-        }
-        c64.CHROUT('\n')
-
-        repeat 1 {
-            c64.CHROUT('1')
-            continue
-            break
-        }
-        c64.CHROUT('\n')
-
-        repeat 255 {
-            c64.CHROUT('@')
-        }
-        c64.CHROUT('\n')
-        repeat 256 {
-            c64.CHROUT('!')
-        }
-        c64.CHROUT('\n')
-
-        uword teller
-        repeat 4000 {
-            teller++
-        }
-        c64scr.print_uw(teller)
-        c64.CHROUT('\n')
-
-
-        repeat {
-        }
 
      }
 }

examples/turtle-gfx.p8

@@ -11,12 +11,12 @@ main {
         graphics.enable_bitmap_mode()
         turtle.init()
 
-        ubyte i
-        for i in 0 to 255 {
+        repeat 100 {
             while c64.RASTER {
             }
         }
 
+        ubyte i
         for i in 0 to 100 {
             turtle.fd(i+20)
             turtle.rt(94)