Redundant curly braces in string template: do not report labeled 'this'

#KT-35475 Fixed

idea/idea-core/src/org/jetbrains/kotlin/idea/core/psiModificationUtils.kt

@@ -542,8 +542,11 @@ fun KtModifierList.normalize(): KtModifierList {
     }
 }
 
-fun KtBlockStringTemplateEntry.canDropBraces() =
-    (expression is KtNameReferenceExpression || expression is KtThisExpression) && canPlaceAfterSimpleNameEntry(nextSibling)
+fun KtBlockStringTemplateEntry.canDropBraces(): Boolean {
+    val expression = this.expression
+    return (expression is KtNameReferenceExpression || (expression is KtThisExpression && expression.labelQualifier == null))
+            && canPlaceAfterSimpleNameEntry(nextSibling)
+}
 
 fun KtBlockStringTemplateEntry.dropBraces(): KtSimpleNameStringTemplateEntry {
     val name = if (expression is KtThisExpression) {

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/necessaryBrackets8.kt

@@ -0,0 +1,12 @@
+// PROBLEM: none
+fun main() {
+    "hello".foo()
+}
+
+fun bar(block: Int.() -> Unit) { block(42) }
+
+fun String.foo() = bar {
+    println("this: <caret>${this@foo}")
+}
+
+fun println(s: String) {}

idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java

@@ -8247,6 +8247,11 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             runTest("idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/necessaryBrackets7.kt");
         }
 
+        @TestMetadata("necessaryBrackets8.kt")
+        public void testNecessaryBrackets8() throws Exception {
+            runTest("idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/necessaryBrackets8.kt");
+        }
+
         @TestMetadata("unnecessaryBrackets1.kt")
         public void testUnnecessaryBrackets1() throws Exception {
             runTest("idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets1.kt");