fix compiler error caused by removal of string symbol in txt.print() optimization

codeOptimizers/src/prog8/optimizer/StatementOptimizer.kt

@@ -45,11 +45,7 @@ class StatementOptimizer(private val program: Program,
                             mutableListOf(NumericLiteral(DataType.UBYTE, firstCharEncoded.toDouble(), pos)),
                             functionCallStatement.void, pos
                         )
-                        val stringDecl = string.parent as VarDecl
-                        return listOf(
-                            IAstModification.ReplaceNode(functionCallStatement, chrout, parent),
-                            IAstModification.Remove(stringDecl, stringDecl.parent as IStatementContainer)
-                        )
+                        return listOf(IAstModification.ReplaceNode(functionCallStatement, chrout, parent))
                     } else if (string.value.length == 2) {
                         val firstTwoCharsEncoded = options.compTarget.encodeString(string.value.take(2), string.encoding)
                         val chrout1 = FunctionCallStatement(
@@ -62,11 +58,9 @@ class StatementOptimizer(private val program: Program,
                             mutableListOf(NumericLiteral(DataType.UBYTE, firstTwoCharsEncoded[1].toDouble(), pos)),
                             functionCallStatement.void, pos
                         )
-                        val stringDecl = string.parent as VarDecl
                         return listOf(
                             IAstModification.InsertBefore(functionCallStatement, chrout1, parent as IStatementContainer),
-                            IAstModification.ReplaceNode(functionCallStatement, chrout2, parent),
-                            IAstModification.Remove(stringDecl, stringDecl.parent as IStatementContainer)
+                            IAstModification.ReplaceNode(functionCallStatement, chrout2, parent)
                         )
                     }
                 }

compiler/test/TestOptimization.kt

@@ -16,6 +16,7 @@ import prog8.code.core.DataType
 import prog8.code.core.Position
 import prog8.code.target.C64Target
 import prog8.code.target.Cx16Target
+import prog8.code.target.VMTarget
 import prog8tests.helpers.*
 
 
@@ -758,4 +759,21 @@ main {
 }"""
         compileText(C64Target(), true, text, writeAssembly = false) shouldNotBe null
     }
+
+    test("replacing string print by chrout with referenced string elsewhere shouldn't give string symbol error") {
+        val text="""
+%import textio
+
+main {
+    sub start() {
+        str key = "test"
+        txt.print(":")
+        if key != ":" {
+            cx16.r0++
+        }
+    }
+}
+"""
+        compileText(VMTarget(), true, text, writeAssembly = false) shouldNotBe null
+    }
 })

docs/source/todo.rst

@@ -2,8 +2,6 @@
 TODO
 ====
 
-- fix discord string bug for if key!="." : "ERROR undefined symbol: prog8_interned_strings.string_3"
-
 - txt.waitkey() should return the pressed key? Also on atari.
 
 - [on branch: shortcircuit] investigate McCarthy evaluation again? this may also reduce code size perhaps for things like if a>4 or a<2 ....