Support mutable collection types in typeOf

flexibleTypes_1_6.kt is fixed for JVM IR in a subsequent commit.

 #KT-35877 Fixed

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

@@ -5,12 +5,14 @@
 
 package org.jetbrains.kotlin.codegen.inline
 
+import org.jetbrains.kotlin.builtins.jvm.JavaToKotlinClassMap
 import org.jetbrains.kotlin.codegen.*
 import org.jetbrains.kotlin.codegen.state.GenerationState
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.descriptors.PropertyDescriptor
 import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor
+import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameUnsafe
 import org.jetbrains.kotlin.resolve.jvm.AsmTypes.*
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.model.TypeParameterMarker
@@ -56,5 +58,10 @@ class PsiInlineIntrinsicsSupport(override val state: GenerationState) : ReifiedT
         )
     }
 
+    override fun isMutableCollectionType(type: KotlinType): Boolean {
+        val classifier = type.constructor.declarationDescriptor
+        return classifier is ClassDescriptor && JavaToKotlinClassMap.isMutable(classifier.fqNameUnsafe)
+    }
+
     override fun toKotlinType(type: KotlinType): KotlinType = type
 }

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

@@ -70,6 +70,8 @@ class ReifiedTypeInliner<KT : KotlinTypeMarker>(
 
         fun generateTypeParameterContainer(v: InstructionAdapter, typeParameter: TypeParameterMarker)
 
+        fun isMutableCollectionType(type: KT): Boolean
+
         fun toKotlinType(type: KT): KotlinType
     }
 

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

@@ -90,13 +90,19 @@ 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)
+    if (intrinsicsSupport.state.stableTypeOf) {
+        if (intrinsicsSupport.isMutableCollectionType(type)) {
+            v.invokestatic(REFLECTION, "mutableCollectionType", Type.getMethodDescriptor(K_TYPE, K_TYPE), false)
+        }
 
-        v.invokestatic(REFLECTION, "platformType", Type.getMethodDescriptor(K_TYPE, K_TYPE, K_TYPE), false)
+        if (type.isFlexible()) {
+            // 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)
+        }
     }
 }