Fix @Language injection when using named parameters

Start using names of arguments if they are available when fetching
the @Language injection information.

Fixes KT-35859

idea/idea-jvm/src/org/jetbrains/kotlin/idea/injection/KotlinLanguageInjector.kt

@@ -347,9 +347,14 @@ class KotlinLanguageInjector(
     }
 
     private fun injectionForKotlinCall(argument: KtValueArgument, ktFunction: KtFunction, reference: PsiReference): InjectionInfo? {
+        val argumentName = argument.getArgumentName()?.asName
         val argumentIndex = (argument.parent as KtValueArgumentList).arguments.indexOf(argument)
-        val ktParameter = ktFunction.valueParameters.getOrNull(argumentIndex) ?: return null
+        // Prefer using argument name if present
-
+        val ktParameter = if (argumentName != null) {
+            ktFunction.valueParameters.firstOrNull { it.nameAsName == argumentName }
+        } else {
+            ktFunction.valueParameters.getOrNull(argumentIndex)
+        } ?: return null
         val patternInjection = findInjection(ktParameter, configuration.getInjections(KOTLIN_SUPPORT_ID))
         if (patternInjection != null) {
             return patternInjection
@@ -363,7 +368,11 @@ class KotlinLanguageInjector(
             ktReference.resolveToDescriptors(bindingContext).singleOrNull() as? FunctionDescriptor
         } ?: return null
 
-        val parameterDescriptor = functionDescriptor.valueParameters.getOrNull(argumentIndex) ?: return null
+        val parameterDescriptor = if (argumentName != null) {
+            functionDescriptor.valueParameters.firstOrNull { it.name == argumentName }
+        } else {
+            functionDescriptor.valueParameters.getOrNull(argumentIndex)
+        } ?: return null
         return injectionInfoByAnnotation(parameterDescriptor)
     }
 

idea/tests/org/jetbrains/kotlin/psi/KotlinInjectionTest.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.psi
 
 import com.intellij.codeInsight.completion.CompletionType
 import com.intellij.lang.html.HTMLLanguage
+import com.intellij.lang.xml.XMLLanguage
 import com.intellij.openapi.fileTypes.PlainTextLanguage
 import org.intellij.lang.annotations.Language
 import org.intellij.lang.regexp.RegExpLanguage
@@ -780,5 +781,26 @@ class KotlinInjectionTest : AbstractInjectionTest() {
         languageId = HTMLLanguage.INSTANCE.id, unInjectShouldBePresent = false
     )
 
+    fun testInjectionWithUsageInFunctionWithMarkedSecondNamedParameterWithAnnotation() = doInjectionPresentTest(
+        """
+            import org.intellij.lang.annotations.Language
+
+            fun foo(@Language("XML") a: String = "", @Language("HTML") b: String = "") {}
+
+            fun other() { foo(b = "some<caret>") }
+            """,
+        languageId = HTMLLanguage.INSTANCE.id, unInjectShouldBePresent = false
+    )
+
+    fun testInjectionWithUsageInFunctionWithMarkedFirstNamedParameterWithAnnotation() = doInjectionPresentTest(
+        """
+            import org.intellij.lang.annotations.Language
+
+            fun foo(@Language("XML") a: String = "", @Language("HTML") b: String = "") {}
+
+            fun other() { foo(a = "some<caret>") }
+            """,
+        languageId = XMLLanguage.INSTANCE.id, unInjectShouldBePresent = false
+    )
 }