Report unsupported on using underscored type argument if the corresponding feature is disabled

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tower/PSICallResolver.kt

@@ -691,7 +691,7 @@ class PSICallResolver(
 
             val typeReference = projection.typeReference ?: return@map TypeArgumentPlaceholder
 
-            if (typeReference.isPlaceholder && arePartiallySpecifiedTypeArgumentsEnabled) {
+            if (typeReference.isPlaceholder) {
                 val resolvedAnnotations = typeResolver.resolveTypeAnnotations(context.trace, context.scope, typeReference)
                     .apply(ForceResolveUtil::forceResolveAllContents)
 
@@ -700,6 +700,10 @@ class PSICallResolver(
                     context.trace.report(Errors.UNSUPPORTED.on(annotationElement, "annotations on an underscored type argument"))
                 }
 
+                if (!arePartiallySpecifiedTypeArgumentsEnabled) {
+                    context.trace.report(Errors.UNSUPPORTED.on(typeReference, "underscored type argument"))
+                }
+
                 return@map TypeArgumentPlaceholder
             }
 

compiler/testData/diagnostics/tests/inference/underscoredTypeArgument.fir.kt

@@ -1,4 +1,4 @@
-// FIR_IDENTICAL
+// !LANGUAGE: -PartiallySpecifiedTypeArguments
 // !DIAGNOSTICS: -UNCHECKED_CAST
 // WITH_RUNTIME
 

compiler/testData/diagnostics/tests/inference/underscoredTypeArgument.kt

@@ -1,9 +1,10 @@
+// !LANGUAGE: -PartiallySpecifiedTypeArguments
 // !DIAGNOSTICS: -UNCHECKED_CAST
 // WITH_RUNTIME
 
 fun <K, T> foo(x: (K) -> T): Pair<K, T> = (1 as K) to (1f as T)
 
 fun box(): String {
-    val x = foo<Int, <!UNRESOLVED_REFERENCE!>_<!>> { it.toFloat() } // Pair<Int, Float>
+    val x = foo<Int, <!UNSUPPORTED("underscored type argument")!>_<!>> { it.toFloat() } // Pair<Int, Float>
     return "OK"
 }