fix regression: don't add 0 initializer when variable is assigned to anyway (or is loopvar in a for-loop)

compiler/res/prog8lib/prog8_lib.p8

@@ -10,6 +10,7 @@ prog8_lib {
 	word @zp retval_interm_w        ; to store intermediary expression results for return values (hopefully allocated on ZP to reduce code size)
 	ubyte @zp retval_interm_ub      ; to store intermediary expression results for return values (hopefully allocated on ZP to reduce code size)
 	byte @zp retval_interm_b        ; to store intermediary expression results for return values (hopefully allocated on ZP to reduce code size)
+	; NOTE: these variables are checked in the StatementReorderer (in fun after(decl: VarDecl)), for these exact names!
 
 	asmsub pattern_match(str string @AY, str pattern @R0) clobbers(Y) -> ubyte @A {
 		%asm {{

compiler/src/prog8/compiler/astprocessing/StatementReorderer.kt

@@ -47,12 +47,20 @@ internal class StatementReorderer(val program: Program, val errors: IErrorReport
                 if (decl.value == null) {
                     if (!decl.autogeneratedDontRemove && decl.allowInitializeWithZero) {
                         // A numeric vardecl without an initial value is initialized with zero,
-                        // unless there's already an assignment below, that initializes the value.
+                        // unless there's already an assignment below it, that initializes the value (or a for loop that uses it as loopvar).
                         // This allows you to restart the program and have the same starting values of the variables
                         // So basically consider 'ubyte xx' as a short form for 'ubyte xx; xx=0'
                         decl.value = null
-                        val nextAssign = decl.nextSibling() as? Assignment
+                        if(decl.name.startsWith("retval_interm_") && decl.definingScope.name=="prog8_lib") {
-                        if (nextAssign == null || !(nextAssign.target isSameAs IdentifierReference(listOf(decl.name), Position.DUMMY))) {
+                            // no need to zero out the special internal returnvalue intermediates.
+                            return noModifications
+                        }
+                        val nextStmt  = decl.nextSibling()
+                        val nextAssign = nextStmt as? Assignment
+                        val nextFor = nextStmt as? ForLoop
+                        val hasNextForWithThisLoopvar = nextFor?.loopVar?.nameInSource==listOf(decl.name)
+                        val hasNextAssignment = nextAssign!=null && nextAssign.target isSameAs IdentifierReference(listOf(decl.name), Position.DUMMY)
+                        if (!hasNextAssignment && !hasNextForWithThisLoopvar) {
                             // Add assignment to initialize with zero
                             // Note: for block-level vars, this will introduce assignments in the block scope. These have to be dealt with correctly later.
                             val identifier = IdentifierReference(listOf(decl.name), decl.position)

docs/source/todo.rst

@@ -6,7 +6,6 @@ For next compiler release (7.2)
 - fix the asm-labels problem (github issue #62)
 - find a way to optimize asm-subroutine param passing where it now sometimes uses the evalstack?
 - analyze (and fix?): TODO why are these bigger now than before the var-initializer optimization:
-    ;    wizzine
     ;    wormfood
     ;    cube3d-float (THIS ONE IS A LOT BIGGER!!)
     ;    cube3d-sprites