Put using underscored type arguments under a feature

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerTestFE10TestdataTestGenerated.java

@@ -13479,6 +13479,12 @@ public class DiagnosisCompilerTestFE10TestdataTestGenerated extends AbstractDiag
                 runTest("compiler/testData/diagnostics/tests/inference/typeParameterInConstructor.kt");
             }
 
+            @Test
+            @TestMetadata("underscoredTypeArgument.kt")
+            public void testUnderscoredTypeArgument() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/inference/underscoredTypeArgument.kt");
+            }
+
             @Test
             @TestMetadata("useFunctionLiteralsToInferType.kt")
             public void testUseFunctionLiteralsToInferType() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java

@@ -13479,6 +13479,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                 runTest("compiler/testData/diagnostics/tests/inference/typeParameterInConstructor.kt");
             }
 
+            @Test
+            @TestMetadata("underscoredTypeArgument.kt")
+            public void testUnderscoredTypeArgument() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/inference/underscoredTypeArgument.kt");
+            }
+
             @Test
             @TestMetadata("useFunctionLiteralsToInferType.kt")
             public void testUseFunctionLiteralsToInferType() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsWithLightTreeTestGenerated.java

@@ -13479,6 +13479,12 @@ public class FirOldFrontendDiagnosticsWithLightTreeTestGenerated extends Abstrac
                 runTest("compiler/testData/diagnostics/tests/inference/typeParameterInConstructor.kt");
             }
 
+            @Test
+            @TestMetadata("underscoredTypeArgument.kt")
+            public void testUnderscoredTypeArgument() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/inference/underscoredTypeArgument.kt");
+            }
+
             @Test
             @TestMetadata("useFunctionLiteralsToInferType.kt")
             public void testUseFunctionLiteralsToInferType() throws Exception {

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

@@ -77,6 +77,8 @@ class PSICallResolver(
 ) {
     private val givenCandidatesName = Name.special("<given candidates>")
 
+    private val arePartiallySpecifiedTypeArgumentsEnabled = languageVersionSettings.supportsFeature(LanguageFeature.PartiallySpecifiedTypeArguments)
+
     val defaultResolutionKinds = setOf(
         NewResolutionOldInference.ResolutionKind.Function,
         NewResolutionOldInference.ResolutionKind.Variable,
@@ -689,7 +691,7 @@ class PSICallResolver(
 
             val typeReference = projection.typeReference ?: return@map TypeArgumentPlaceholder
 
-            if (typeReference.isPlaceholder) {
+            if (typeReference.isPlaceholder && arePartiallySpecifiedTypeArgumentsEnabled) {
                 val resolvedAnnotations = typeResolver.resolveTypeAnnotations(context.trace, context.scope, typeReference)
                     .apply(ForceResolveUtil::forceResolveAllContents)
 

compiler/testData/codegen/box/underscoredTypeArguments/backTicked.kt

@@ -1,3 +1,4 @@
+// !LANGUAGE: +PartiallySpecifiedTypeArguments
 // WITH_RUNTIME
 
 fun <K, T> foo(x: (K) -> T): Pair<K, T> = (1 as K) to (1f as T)

compiler/testData/codegen/box/underscoredTypeArguments/dependentTypeParameters.kt

@@ -1,3 +1,4 @@
+// !LANGUAGE: +PartiallySpecifiedTypeArguments
 // WITH_RUNTIME
 // TARGET_BACKEND: JVM
 

compiler/testData/codegen/box/underscoredTypeArguments/lambdaInputType.kt

@@ -1,3 +1,5 @@
+// !LANGUAGE: +PartiallySpecifiedTypeArguments
+
 sealed class MyResult<out T>{
     data class Success<T>(val value: T): MyResult<T>()
     data class Failure(val exception: Throwable): MyResult<Nothing>()

compiler/testData/codegen/box/underscoredTypeArguments/react.kt

@@ -1,3 +1,5 @@
+// !LANGUAGE: +PartiallySpecifiedTypeArguments
+
 interface RProps
 open class RComponent<K, T> : Component<K, T>
 interface RState

compiler/testData/codegen/box/underscoredTypeArguments/simple.kt

@@ -1,3 +1,4 @@
+// !LANGUAGE: +PartiallySpecifiedTypeArguments
 // WITH_RUNTIME
 
 fun <K, T> foo(x: (K) -> T): Pair<K, T> = (1 as K) to (1f as T)

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

@@ -1,3 +1,4 @@
+// !LANGUAGE: +PartiallySpecifiedTypeArguments
 // !DIAGNOSTICS: -UNCHECKED_CAST
 // FIR_IDENTICAL
 // WITH_RUNTIME

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

@@ -0,0 +1,10 @@
+// FIR_IDENTICAL
+// !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>
+    return "OK"
+}

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

@@ -0,0 +1,4 @@
+package
+
+public fun box(): kotlin.String
+public fun </*0*/ K, /*1*/ T> foo(/*0*/ x: (K) -> T): kotlin.Pair<K, T>

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -13485,6 +13485,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                 runTest("compiler/testData/diagnostics/tests/inference/typeParameterInConstructor.kt");
             }
 
+            @Test
+            @TestMetadata("underscoredTypeArgument.kt")
+            public void testUnderscoredTypeArgument() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/inference/underscoredTypeArgument.kt");
+            }
+
             @Test
             @TestMetadata("useFunctionLiteralsToInferType.kt")
             public void testUseFunctionLiteralsToInferType() throws Exception {

compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt

@@ -238,6 +238,7 @@ enum class LanguageFeature(
     ProhibitNonExhaustiveIfInRhsOfElvis(KOTLIN_1_7, kind = BUG_FIX), // KT-44705
     ForbidExposingTypesInPrimaryConstructorProperties(KOTLIN_1_7, kind = BUG_FIX),
     ProhibitAccessToEnumCompanionMembersInEnumConstructorCall(KOTLIN_1_7, kind = BUG_FIX),
+    PartiallySpecifiedTypeArguments(KOTLIN_1_7),
 
     // 1.8