From d0f51928deba8dfe166d4cf4920672633a667572 Mon Sep 17 00:00:00 2001
From: sergeych <real.sergeych@gmail.com>
Date: Wed, 22 Apr 2026 08:56:02 +0300
Subject: [PATCH] fixed wrong error message in val ++/--

---
 .../lyng/bytecode/BytecodeCompiler.kt         | 30 ++++++++++++-------
 .../kotlin/net/sergeych/lyng/OptTest.kt       | 17 ++++++++---
 2 files changed, 32 insertions(+), 15 deletions(-)

diff --git a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeCompiler.kt b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeCompiler.kt
index 2b67ffe..cc7f558 100644
--- a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeCompiler.kt
+++ b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeCompiler.kt
@@ -2559,11 +2559,7 @@ class BytecodeCompiler(
                 return value
             }
             if (!localTarget.isMutable || localTarget.isDelegated) {
-                val msgId = builder.addConst(BytecodeConst.StringVal("can't reassign val ${localTarget.name}"))
-                val msgSlot = allocSlot()
-                builder.emit(Opcode.CONST_OBJ, msgId, msgSlot)
-                val posId = builder.addConst(BytecodeConst.PosVal(localTarget.pos()))
-                builder.emit(Opcode.THROW, posId, msgSlot)
+                emitImmutableLocalReassignError(localTarget.name, localTarget.pos())
                 return value
             }
             val slot = resolveCapturedOwnerScopeSlot(localTarget)
@@ -2607,12 +2603,8 @@ class BytecodeCompiler(
                 return value
             }
             if (!isMutable) {
-                val msgId = builder.addConst(BytecodeConst.StringVal("can't reassign val $nameTarget"))
-                val msgSlot = allocSlot()
-                builder.emit(Opcode.CONST_OBJ, msgId, msgSlot)
                 val pos = (ref.target as? LocalVarRef)?.pos() ?: Pos.builtIn
-                val posId = builder.addConst(BytecodeConst.PosVal(pos))
-                builder.emit(Opcode.THROW, posId, msgSlot)
+                emitImmutableLocalReassignError(nameTarget, pos)
                 return value
             }
             if (slot < scopeSlotCount && value.type != SlotType.UNKNOWN) {
@@ -3904,7 +3896,10 @@ class BytecodeCompiler(
                 val errorSlot = emitLoopVarReassignError(target.name, target.pos())
                 return CompiledValue(errorSlot, SlotType.OBJ)
             }
-            if (!target.isMutable) return null
+            if (!target.isMutable) {
+                val errorSlot = emitImmutableLocalReassignError(target.name, target.pos())
+                return CompiledValue(errorSlot, SlotType.OBJ)
+            }
             if (target.isDelegated) {
                 val slot = resolveSlot(target) ?: return null
                 if (slot < scopeSlotCount) return null
@@ -4078,6 +4073,10 @@ class BytecodeCompiler(
                 val errorSlot = emitLoopVarReassignError(varTarget.name, varTarget.pos())
                 return CompiledValue(errorSlot, SlotType.OBJ)
             }
+            if (resolved != null && !resolved.second) {
+                val errorSlot = emitImmutableLocalReassignError(varTarget.name, varTarget.pos())
+                return CompiledValue(errorSlot, SlotType.OBJ)
+            }
         }
 
         val thisFieldTarget = ref.target as? ThisFieldSlotRef
@@ -8438,6 +8437,15 @@ class BytecodeCompiler(
         builder.emit(Opcode.THROW, posId, msgSlot)
         return msgSlot
     }
+
+    private fun emitImmutableLocalReassignError(name: String, pos: Pos): Int {
+        val msgId = builder.addConst(BytecodeConst.StringVal("can't reassign val $name"))
+        val msgSlot = allocSlot()
+        builder.emit(Opcode.CONST_OBJ, msgId, msgSlot)
+        val posId = builder.addConst(BytecodeConst.PosVal(pos))
+        builder.emit(Opcode.THROW, posId, msgSlot)
+        return msgSlot
+    }
     private fun binaryLeft(ref: BinaryOpRef): ObjRef = ref.left
     private fun binaryRight(ref: BinaryOpRef): ObjRef = ref.right
     private fun binaryOp(ref: BinaryOpRef): BinOp = ref.op
diff --git a/lynglib/src/commonTest/kotlin/net/sergeych/lyng/OptTest.kt b/lynglib/src/commonTest/kotlin/net/sergeych/lyng/OptTest.kt
index 1cb2d8b..602acd6 100644
--- a/lynglib/src/commonTest/kotlin/net/sergeych/lyng/OptTest.kt
+++ b/lynglib/src/commonTest/kotlin/net/sergeych/lyng/OptTest.kt
@@ -17,12 +17,12 @@
 
 package net.sergeych.lyng
 
-import kotlinx.coroutines.delay
 import kotlinx.coroutines.test.runTest
 import net.sergeych.lyng.obj.toInt
 import kotlin.test.Test
+import kotlin.test.assertContains
 import kotlin.test.assertEquals
-import kotlin.time.Duration.Companion.milliseconds
+import kotlin.test.assertFailsWith
 import kotlin.time.TimeSource
 
 class OptTest {
@@ -42,7 +42,6 @@ class OptTest {
         repeat(3) { pass ->
             val size = scope.eval("buildArray(200000)").toInt()
             assertEquals(200000, size, "warmup pass ${pass + 1} failed")
-            delay(100)
         }
 
 
@@ -80,5 +79,15 @@ class OptTest {
         """.trimIndent()
         )
     }
-}
 
+    @Test
+    fun testErrorMessage() = runTest {
+        val ex = assertFailsWith<ScriptError> {
+            eval("""
+                val a = 1
+                a++
+            """.trimIndent())
+        }
+        assertContains(ex.errorMessage, "can't reassign val a")
+    }
+}