[kotlin] take prefix into account when injecting into multi-dollar strings

KTIJ-33031

GitOrigin-RevId: 3d5253791733df4c821c40a2659b03c591275f5b

plugins/kotlin/injection/base/src/org/jetbrains/kotlin/idea/base/injection/KotlinLanguageInjectionPerformerBase.kt

@@ -73,7 +73,8 @@ abstract class KotlinLanguageInjectionPerformerBase : LanguageInjectionPerformer
                                              ContainerUtil.concat(listOfNotNull(child.left, child.right), tail), pendingPrefix, unparseable, collected)
                 }
                 child is KtStringTemplateExpression -> {
-                    if (child.children.isEmpty()) {
+                    val entries = child.entries
+                    if (entries.isEmpty()) {
                         // empty range to save injection in the empty string
                         collected += injectionRange(
                             child,
@@ -83,7 +84,7 @@ abstract class KotlinLanguageInjectionPerformerBase : LanguageInjectionPerformer
                         )
                     }
                     return collectInjections(child,
-                                             ContainerUtil.concat(child.children.toList(), tail), pendingPrefix, unparseable, collected)
+                        ContainerUtil.concat(entries.toList(), tail), pendingPrefix, unparseable, collected)
                 }
                 literal == null -> {
                     val (prefix, myUnparseable) = makePlaceholder(child)

plugins/kotlin/injection/k2/tests/test/org/jetbrains/kotlin/idea/k2/injection/K2KotlinInjectionTest.kt

@@ -8,6 +8,7 @@ import org.jetbrains.kotlin.idea.base.injection.KotlinInjectionTestBase
 import org.jetbrains.kotlin.idea.base.plugin.KotlinPluginMode
 import org.jetbrains.kotlin.idea.fir.invalidateCaches
 import org.jetbrains.kotlin.idea.test.KotlinWithJdkAndRuntimeLightProjectDescriptor
+import org.jetbrains.kotlin.idea.test.withCustomCompilerOptions
 
 class K2KotlinInjectionTest: KotlinInjectionTestBase() {
 
@@ -41,4 +42,30 @@ class K2KotlinInjectionTest: KotlinInjectionTestBase() {
 
         assertEquals("Wrong injection language", KotlinLanguage.INSTANCE, injectedFile?.language)
     }
+
+    fun testInjectionIntoMultiDollarString() {
+        val file = myFixture.configureByText(
+            "a.kt",
+            """
+                // COMPILER_ARGUMENTS: -Xmulti-dollar-interpolation
+                
+                import org.intellij.lang.annotations.Language
+                
+                @Language("JSON")
+                val json = $$$""${'"'}
+                {
+                  "openapi": "3.0.2",
+                  "info": {
+                    "title": "REST",
+                    "version": "1.0.0"
+                  }
+                }
+                ""${'"'}
+            """.trimIndent()
+        )
+
+        withCustomCompilerOptions(file.text, project, module) {
+            myFixture.checkHighlighting()
+        }
+    }
 }