[command-completion] IDEA-385364 Generation doesn't work on a new line with tabs

GitOrigin-RevId: 36a9526f790baae02f68afdc7e7bbfe5bde75217

java/java-tests/testSrc/com/intellij/java/codeInsight/completion/commands/JavaCommandsCompletionGenerateTest.kt

@@ -8,7 +8,7 @@ import com.intellij.openapi.util.registry.Registry
 import com.intellij.testFramework.NeedsIndex
 
 @NeedsIndex.SmartMode(reason = "it requires highlighting")
-class JavaCommandsCompletionGenerateConstructorsTest : LightFixtureCompletionTestCase() {
+class JavaCommandsCompletionGenerateTest : LightFixtureCompletionTestCase() {
 
   override fun setUp() {
     super.setUp()
@@ -16,6 +16,33 @@ class JavaCommandsCompletionGenerateConstructorsTest : LightFixtureCompletionTes
     Registry.get("ide.completion.command.force.enabled").setValue(true, getTestRootDisposable())
   }
 
+  fun testGenerateWithTabs() {
+    //don't move, there are tabs instead of spaces
+    val text = """
+package org.test;
+
+public class Test {
+	private Integer num;
+
+
+	ge<caret>
+}""".trimIndent()
+    myFixture.configureByText(JavaFileType.INSTANCE, text)
+    val elements = myFixture.completeBasic()
+    selectItem(elements.first { element -> element.lookupString.contains("Generate 'No-Args Constructor'", ignoreCase = true) })
+    NonBlockingReadActionImpl.waitForAsyncTaskCompletion()
+    myFixture.checkResult("""
+package org.test;
+
+public class Test {
+	private Integer num;
+
+
+    public Test() {
+    }
+}""".trimIndent())
+  }
+
   fun testGenerateNoArgsConstructor() {
     myFixture.configureByText(JavaFileType.INSTANCE, """
       class A { 

platform/lang-impl/src/com/intellij/codeInsight/completion/command/CommandCompletionProvider.kt

@@ -614,6 +614,7 @@ internal fun findActualIndex(suffix: String, text: CharSequence, offset: Int): I
     var currentIndex = 1
     while (text.getOrNull(offset - currentIndex)?.isLetter() == true ||
            text.getOrNull(offset - currentIndex) == ' ' ||
+           text.getOrNull(offset - currentIndex) == '\t' ||
            text.getOrNull(offset - currentIndex) == '\''
     ) {
       currentIndex++