IR: add IrClass.getInlineClassRepresentation, serialize/deserialize it

The change in FirDeclarationUtil is needed because in case of unsigned
types loaded from the standard library, the primary constructor for some
reason is not the first, but the second in the list of constructors.

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/ClassGenerator.kt

@@ -29,6 +29,7 @@ import org.jetbrains.kotlin.ir.expressions.impl.IrReturnImpl
 import org.jetbrains.kotlin.ir.expressions.mapValueParameters
 import org.jetbrains.kotlin.ir.expressions.putTypeArguments
 import org.jetbrains.kotlin.ir.expressions.typeParametersCount
+import org.jetbrains.kotlin.ir.types.IrSimpleType
 import org.jetbrains.kotlin.ir.util.SYNTHETIC_OFFSET
 import org.jetbrains.kotlin.ir.util.createIrClassFromDescriptor
 import org.jetbrains.kotlin.ir.util.declareSimpleFunctionWithOverrides
@@ -121,6 +122,11 @@ class ClassGenerator(
             generateFakeOverrideMemberDeclarations(irClass, ktClassOrObject)
 
             if (irClass.isInline && ktClassOrObject is KtClassOrObject) {
+                val representation = classDescriptor.inlineClassRepresentation
+                    ?: error("Unknown representation for inline class: $classDescriptor")
+                irClass.inlineClassRepresentation = representation.mapUnderlyingType { type ->
+                    type.toIrType() as? IrSimpleType ?: error("Inline class underlying type is not a simple type: $classDescriptor")
+                }
                 generateAdditionalMembersForInlineClasses(irClass, ktClassOrObject)
             }
 

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/StandaloneDeclarationGenerator.kt

@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.IrExpressionBody
 import org.jetbrains.kotlin.ir.symbols.*
+import org.jetbrains.kotlin.ir.types.IrSimpleType
 import org.jetbrains.kotlin.ir.types.impl.IrUninitializedType
 import org.jetbrains.kotlin.ir.util.createIrClassFromDescriptor
 import org.jetbrains.kotlin.ir.util.withScope
@@ -76,7 +77,9 @@ class StandaloneDeclarationGenerator(private val context: GeneratorContext) {
         }
     }
 
-    fun generateClass(startOffset: Int, endOffset: Int, origin: IrDeclarationOrigin, descriptor: ClassDescriptor, symbol: IrClassSymbol): IrClass {
+    fun generateClass(
+        startOffset: Int, endOffset: Int, origin: IrDeclarationOrigin, descriptor: ClassDescriptor, symbol: IrClassSymbol
+    ): IrClass {
         val irClass = irFactory.createIrClassFromDescriptor(startOffset, endOffset, origin, symbol, descriptor)
 
         symbolTable.withScope(irClass) {
@@ -93,6 +96,8 @@ class StandaloneDeclarationGenerator(private val context: GeneratorContext) {
                 descriptor.thisAsReceiverParameter,
                 descriptor.thisAsReceiverParameter.type.toIrType()
             ).also { it.parent = irClass }
+
+            irClass.inlineClassRepresentation = descriptor.inlineClassRepresentation?.mapUnderlyingType { it.toIrType() as IrSimpleType }
         }
 
         return irClass