fix: allow scoped variables such as cx16.rX as loop variable in forloops

compilerAst/src/prog8/ast/antlr/Antlr2Kotlin.kt

@@ -545,7 +545,7 @@ private fun Prog8ANTLRParser.BranchconditionContext.toAst() = BranchCondition.va
 )
 
 private fun Prog8ANTLRParser.ForloopContext.toAst(): ForLoop {
-    val loopvar = identifier().toAst()
+    val loopvar = scoped_identifier().toAst()
     val iterable = expression()!!.toAst()
     val scope =
             if(statement()!=null)

docs/source/programming.rst

@@ -433,7 +433,7 @@ Loops
 -----
 
 The *for*-loop is used to let a variable iterate over a range of values. Iteration is done in steps of 1, but you can change this.
-The loop variable must be declared as byte or word earlier so you can reuse it for multiple occasions.
+The loop variable must be declared separately as byte or word earlier, so that you can reuse it for multiple occasions.
 Iterating with a floating point variable is not supported. If you want to loop over a floating-point array, use a loop with an integer index variable instead.
 
 The *while*-loop is used to repeat a piece of code while a certain condition is still true.

docs/source/syntaxreference.rst

@@ -643,8 +643,7 @@ Loops
 for loop
 ^^^^^^^^
 
-The loop variable must be a byte or word variable,
-and must be defined first in the local scope of the for loop.
+The loop variable must be a byte or word variable, and it must be defined separately first.
 The expression that you loop over can be anything that supports iteration (such as ranges like ``0 to 100``,
 array variables and strings) *except* floating-point arrays (because a floating-point loop variable is not supported).
 

docs/source/todo.rst

@@ -3,7 +3,6 @@ TODO
 
 For next compiler release (7.5)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-- allow cx16.rX as loop variable in forloops (now requires unqualified identifiername)
 ...
 
 

examples/test.p8

@@ -20,10 +20,14 @@ main {
             txt.print_ub(main.derp.xx)
             txt.spc()
         }
+
+        derp()
         txt.nl()
     }
 
     sub derp() {
         ubyte xx
+
+        xx++
     }
 }

parser/antlr/Prog8ANTLR.g4

@@ -283,7 +283,7 @@ branch_stmt : branchcondition EOL? (statement | statement_block) EOL? else_part?
 branchcondition: 'if_cs' | 'if_cc' | 'if_eq' | 'if_z' | 'if_ne' | 'if_nz' | 'if_pl' | 'if_pos' | 'if_mi' | 'if_neg' | 'if_vs' | 'if_vc' ;
 
 
-forloop :  'for' identifier 'in' expression EOL? (statement | statement_block) ;
+forloop :  'for' scoped_identifier 'in' expression EOL? (statement | statement_block) ;
 
 whileloop:  'while' expression EOL? (statement | statement_block) ;