some fixes in merge3

src/commonMain/kotlin/net.sergeych.merge3/merge3.kt

@@ -5,9 +5,6 @@ import dev.gitlive.difflib.patch.AbstractDelta
 import dev.gitlive.difflib.patch.ChangeDelta
 import dev.gitlive.difflib.patch.DeleteDelta
 import dev.gitlive.difflib.patch.InsertDelta
-import net.sergeych.mp_logger.Log
-import net.sergeych.mp_logger.LogTag
-import net.sergeych.mp_logger.debug
 import net.sergeych.sprintf.sprintf
 
 /**
@@ -77,14 +74,18 @@ sealed class MergedBlock<T> {
 /**
  * Perform 3-way merge. See [merge3] for details.
  */
-private class Merge3<T>(val source: List<T>, val variantA: List<T>, val variantB: List<T>) :
-    LogTag("MRG3", Log.Level.INFO) {
+private class Merge3<T>(val source: List<T>, val variantA: List<T>, val variantB: List<T>,
+    val showDebug: Boolean = false) {
 
     private val reindex = source.indices.toMutableList()
     private val changeCount = MutableList(source.size) { 0 }
 
     val result = source.toMutableList()
 
+    private fun debug( f: ()-> String ) {
+        if( showDebug ) println(f())
+    }
+
     private fun trace() {
 
         debug { result.indices.joinToString("") { "%3d".sprintf(it) } }
@@ -139,15 +140,20 @@ private class Merge3<T>(val source: List<T>, val variantA: List<T>, val variantB
         debug { "deleting $count elements @$sourcePosition" }
         val position = findPosition(sourcePosition)
         var sp = sourcePosition
+        // how much to shoft reindex, depends on actual deletions count:
+        var shift = count
         for (i in position until position + count) {
             // it this position is already removed, do nothing
-            if (reindex[sp] < 0) continue
+            if (reindex[sp] < 0) {
+                shift--
+                continue
+            }
             reindex[sp++] = -1
             result.removeAt(position)
             changeCount.removeAt(position)
         }
         while (sp < reindex.size) {
-            reindex[sp].let { if (it > 0) reindex[sp] = it - count }
+            reindex[sp].let { if (it > 0) reindex[sp] = it - shift }
             sp++
         }
     }
@@ -257,6 +263,4 @@ private class Merge3<T>(val source: List<T>, val variantA: List<T>, val variantB
  * See [MergeResult] for interpreting results
  */
 fun <T> merge3(source: List<T>, a: List<T>, b: List<T>, showDebug: Boolean = false): MergeResult<T> =
-    Merge3(source, a, b).also {
-        if (showDebug) it.logLevel = Log.Level.DEBUG
-    }.perform()
+    Merge3(source, a, b, showDebug).perform()

src/commonTest/kotlin/testMerge.kt

@@ -19,6 +19,20 @@ class BasicTest {
         assertEquals("Bye cruel world!!!", m.merged.str)
 //        assertTrue(m.noConflicts)
     }
+    @Test
+    fun testMergeNoConflicts3() {
+        Log.connectConsole()
+        val src = "1Hello, world!".toList()
+        val a = "Hello, friend!".toList()
+        val b = "Bye world!".toList()
+
+        val m = merge3(src, a, b, true)
+        println(m.merged.str)
+//        println(m.conflicts)
+        println(m.changedAreas)
+        assertEquals("Bye friend!", m.merged.str)
+//        assertTrue(m.noConflicts)
+    }
 
     @Test
     fun testMergeNoConflicts2() {