[FIR] Fix false negative TYPE_PARAMETER_AS_REIFIED_ARRAY

... in presence of typealiases.

#KT-61921

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirReifiedChecker.kt

@@ -11,9 +11,11 @@ import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.diagnostics.chooseFactory
 import org.jetbrains.kotlin.diagnostics.reportOn
 import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
+import org.jetbrains.kotlin.fir.analysis.checkers.fullyExpandedClassId
 import org.jetbrains.kotlin.fir.analysis.diagnostics.*
 import org.jetbrains.kotlin.fir.expressions.FirQualifiedAccessExpression
 import org.jetbrains.kotlin.fir.references.toResolvedCallableSymbol
+import org.jetbrains.kotlin.fir.resolve.fullyExpandedType
 import org.jetbrains.kotlin.fir.symbols.impl.FirRegularClassSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirTypeParameterSymbol
 import org.jetbrains.kotlin.fir.types.*
@@ -58,11 +60,15 @@ object FirReifiedChecker : FirQualifiedAccessExpressionChecker() {
         isExplicit: Boolean,
         isArray: Boolean,
         context: CheckerContext,
-        reporter: DiagnosticReporter
+        reporter: DiagnosticReporter,
     ) {
-        if (typeArgument.classId == StandardClassIds.Array) {
+        val fullyExpandedType = typeArgument.fullyExpandedType(context.session)
-            val nestedTypeArgument = typeArgument.typeArguments[0].type ?: return
+        if (fullyExpandedType.classId == StandardClassIds.Array) {
-            checkArgumentAndReport(nestedTypeArgument, source, isExplicit, isArray = true, context, reporter)
+            // Type aliases can transform type arguments arbitrarily (drop, nest, etc...).
+            // Therefore, we check the arguments of the expanded type, not the ones that went into the type alias.
+            fullyExpandedType.typeArguments.forEach {
+                if (it is ConeKotlinType) checkArgumentAndReport(it, source, isExplicit, isArray = true, context, reporter)
+            }
             return
         }
 

compiler/testData/diagnostics/tests/generics/tpAsReified/GenericArrayAsReifiedArgument.kt

@@ -4,10 +4,16 @@
 
 inline fun <reified T> foo() {}
 
+typealias TA<T, R> = Array<R>
+
 fun <T> bar() {
     foo<<!TYPE_PARAMETER_AS_REIFIED!>T<!>>()
     foo<<!TYPE_PARAMETER_AS_REIFIED_ARRAY_ERROR!>Array<T><!>>()
     foo<<!TYPE_PARAMETER_AS_REIFIED_ARRAY_ERROR!>Array<Array<T>><!>>()
+    foo<TA<T, String>>()
+    foo<<!TYPE_PARAMETER_AS_REIFIED_ARRAY_ERROR!>TA<String, T><!>>()
+    foo<TA<TA<String, T>, String>>()
+    foo<<!TYPE_PARAMETER_AS_REIFIED_ARRAY_ERROR!>TA<String, TA<String, T>><!>>()
     foo<Array<Int>>()
     foo<Array<Array<Int>>>()
     foo<IntArray>()

compiler/testData/diagnostics/tests/generics/tpAsReified/GenericArrayAsReifiedArgument.txt

@@ -1,5 +0,0 @@
-package
-
-public fun </*0*/ T> bar(): kotlin.Unit
-public inline fun </*0*/ reified T> foo(): kotlin.Unit
-public fun test(/*0*/ x: kotlin.Array<kotlin.String>, /*1*/ y: kotlin.Array<*>): kotlin.Unit