Support flexible types internally in typeOf

#KT-45066 Fixed

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/PsiInlineIntrinsicsSupport.kt

@@ -19,7 +19,7 @@ import org.jetbrains.org.objectweb.asm.Type.INT_TYPE
 import org.jetbrains.org.objectweb.asm.Type.VOID_TYPE
 import org.jetbrains.org.objectweb.asm.commons.InstructionAdapter
 
-class PsiInlineIntrinsicsSupport(private val state: GenerationState) : ReifiedTypeInliner.IntrinsicsSupport<KotlinType> {
+class PsiInlineIntrinsicsSupport(override val state: GenerationState) : ReifiedTypeInliner.IntrinsicsSupport<KotlinType> {
     override fun putClassInstance(v: InstructionAdapter, type: KotlinType) {
         DescriptorAsmUtil.putJavaLangClassInstance(v, state.typeMapper.mapType(type), type, state.typeMapper)
     }

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/ReifiedTypeInliner.kt

@@ -20,6 +20,7 @@ import org.jetbrains.kotlin.codegen.generateAsCast
 import org.jetbrains.kotlin.codegen.generateIsCheck
 import org.jetbrains.kotlin.codegen.intrinsics.IntrinsicMethods
 import org.jetbrains.kotlin.codegen.optimization.common.intConstant
+import org.jetbrains.kotlin.codegen.state.GenerationState
 import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.config.isReleaseCoroutines
 import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor
@@ -63,6 +64,8 @@ class ReifiedTypeInliner<KT : KotlinTypeMarker>(
     }
 
     interface IntrinsicsSupport<KT : KotlinTypeMarker> {
+        val state: GenerationState
+
         fun putClassInstance(v: InstructionAdapter, type: KT)
 
         fun generateTypeParameterContainer(v: InstructionAdapter, typeParameter: TypeParameterMarker)

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/typeOf.kt

@@ -89,6 +89,15 @@ fun <KT : KotlinTypeMarker> TypeSystemCommonBackendContext.generateTypeOf(
     }
 
     v.invokestatic(REFLECTION, methodName, signature, false)
+
+    if (type.isFlexible() && intrinsicsSupport.state.stableTypeOf) {
+        // If this is a flexible type, we've just generated its lower bound and have it on the stack.
+        // Let's generate the upper bound now and call the method that takes lower and upper bound and constructs a flexible KType.
+        @Suppress("UNCHECKED_CAST")
+        generateTypeOf(v, type.upperBoundIfFlexible() as KT, intrinsicsSupport)
+
+        v.invokestatic(REFLECTION, "platformType", Type.getMethodDescriptor(K_TYPE, K_TYPE, K_TYPE), false)
+    }
 }
 
 private fun <KT : KotlinTypeMarker> TypeSystemCommonBackendContext.generateNonReifiedTypeParameter(

compiler/backend/src/org/jetbrains/kotlin/codegen/state/GenerationState.kt

@@ -260,6 +260,10 @@ class GenerationState private constructor(
     val useKotlinNothingValueException =
         languageVersionSettings.apiVersion >= ApiVersion.KOTLIN_1_4 &&
                 !configuration.getBoolean(JVMConfigurationKeys.NO_KOTLIN_NOTHING_VALUE_EXCEPTION)
+
+    // In 1.6, `typeOf` became stable and started to rely on a few internal stdlib functions which were missing before 1.6.
+    val stableTypeOf = languageVersionSettings.apiVersion >= ApiVersion.KOTLIN_1_6
+
     val samWrapperClasses: SamWrapperClasses = SamWrapperClasses(this)
     val globalInlineContext: GlobalInlineContext = GlobalInlineContext(diagnostics)
     val mappingsClassesForWhenByEnum: MappingsClassesForWhenByEnum = MappingsClassesForWhenByEnum(this)