IR: do not crash renderer on functions with uninitialized return type

This is a follow-up to b497f39c29. It
turns out that it didn't help because `IrFunction.returnType` throws
exception, and checking for `IrUninitializedType` in `IrType.render` was
already too late. Throw and catch specific exception instead.

Also add function name into the exception message for better diagnostics
elsewhere (can't compute the full FQ name because in cases like
KT-42020, the parent is also uninitialized).

compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/declarations/impl/IrConstructorImpl.kt

@@ -25,6 +25,7 @@ import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.symbols.IrConstructorSymbol
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.impl.IrUninitializedType
+import org.jetbrains.kotlin.ir.types.impl.ReturnTypeIsNotInitializedException
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedContainerSource
 
@@ -54,7 +55,7 @@ class IrConstructorImpl(
 
     override var returnType: IrType = returnType
         get() = if (field === IrUninitializedType) {
-            error("Return type is not initialized")
+            throw ReturnTypeIsNotInitializedException(this)
         } else {
             field
         }

compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/declarations/impl/IrFunctionImpl.kt

@@ -5,9 +5,9 @@
 
 package org.jetbrains.kotlin.ir.declarations.impl
 
+import org.jetbrains.kotlin.descriptors.DescriptorVisibility
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.descriptors.Modality
-import org.jetbrains.kotlin.descriptors.DescriptorVisibility
 import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.descriptors.WrappedSimpleFunctionDescriptor
@@ -17,6 +17,7 @@ import org.jetbrains.kotlin.ir.symbols.IrPropertySymbol
 import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.impl.IrUninitializedType
+import org.jetbrains.kotlin.ir.types.impl.ReturnTypeIsNotInitializedException
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedContainerSource
 
@@ -44,7 +45,7 @@ abstract class IrFunctionCommonImpl(
 
     override var returnType: IrType = returnType
         get() = if (field === IrUninitializedType) {
-            error("Return type is not initialized")
+            throw ReturnTypeIsNotInitializedException(this)
         } else {
             field
         }

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/PersistentIrConstructor.kt

@@ -27,6 +27,7 @@ import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.symbols.IrConstructorSymbol
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.impl.IrUninitializedType
+import org.jetbrains.kotlin.ir.types.impl.ReturnTypeIsNotInitializedException
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedContainerSource
 
@@ -73,7 +74,7 @@ internal class PersistentIrConstructor(
 
     override var returnType: IrType
         get() = returnTypeField.let {
-            if (it !== IrUninitializedType) it else error("Return type is not initialized")
+            if (it !== IrUninitializedType) it else throw ReturnTypeIsNotInitializedException(this)
         }
         set(c) {
             returnTypeField = c

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/PersistentIrFunction.kt

@@ -5,9 +5,9 @@
 
 package org.jetbrains.kotlin.ir.declarations.persistent
 
+import org.jetbrains.kotlin.descriptors.DescriptorVisibility
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.descriptors.Modality
-import org.jetbrains.kotlin.descriptors.DescriptorVisibility
 import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.declarations.persistent.carriers.Carrier
@@ -19,6 +19,7 @@ import org.jetbrains.kotlin.ir.symbols.IrPropertySymbol
 import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.impl.IrUninitializedType
+import org.jetbrains.kotlin.ir.types.impl.ReturnTypeIsNotInitializedException
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedContainerSource
 
@@ -63,7 +64,7 @@ internal abstract class PersistentIrFunctionCommon(
 
     final override var returnType: IrType
         get() = returnTypeField.let {
-            if (it !== IrUninitializedType) it else error("Return type is not initialized")
+            if (it !== IrUninitializedType) it else throw ReturnTypeIsNotInitializedException(this)
         }
         set(c) {
             returnTypeField = c

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/impl/IrTypeBase.kt

@@ -5,8 +5,10 @@
 
 package org.jetbrains.kotlin.ir.types.impl
 
+import org.jetbrains.kotlin.ir.declarations.IrFunction
 import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.types.*
+import org.jetbrains.kotlin.ir.util.fqNameWhenAvailable
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.Variance
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
@@ -63,3 +65,7 @@ object IrUninitializedType : IrType {
 
     override fun hashCode(): Int = System.identityHashCode(this)
 }
+
+class ReturnTypeIsNotInitializedException(function: IrFunction) : IllegalStateException(
+    "Return type is not initialized for function '${function.name}'"
+)

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/RenderIrElement.kt

@@ -28,7 +28,7 @@ import org.jetbrains.kotlin.ir.symbols.IrSymbol
 import org.jetbrains.kotlin.ir.symbols.IrTypeAliasSymbol
 import org.jetbrains.kotlin.ir.symbols.IrVariableSymbol
 import org.jetbrains.kotlin.ir.types.*
-import org.jetbrains.kotlin.ir.types.impl.IrUninitializedType
+import org.jetbrains.kotlin.ir.types.impl.ReturnTypeIsNotInitializedException
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 import org.jetbrains.kotlin.renderer.DescriptorRenderer
 import org.jetbrains.kotlin.types.Variance
@@ -108,8 +108,7 @@ class RenderIrElementVisitor(private val normalizeNames: Boolean = false) : IrEl
         run(fn).trimEnd()
 
     private fun IrType.render(): String =
-        if (this === IrUninitializedType) "<Uninitialized>"
+        "${renderTypeAnnotations(annotations)}${renderTypeInner()}"
-        else "${renderTypeAnnotations(annotations)}${renderTypeInner()}"
 
     private fun IrType.renderTypeInner() =
         when (this) {
@@ -252,7 +251,7 @@ class RenderIrElementVisitor(private val normalizeNames: Boolean = false) : IrEl
 
                 if (declaration is IrSimpleFunction) {
                     append(": ")
-                    append(declaration.returnType.render())
+                    append(declaration.renderReturnType())
                 }
                 append(' ')
 
@@ -282,8 +281,11 @@ class RenderIrElementVisitor(private val normalizeNames: Boolean = false) : IrEl
 
                 append(declaration.name.asString())
 
-                val type = declaration.getter?.returnType ?: declaration.backingField?.type
+                val getter = declaration.getter
-                if (type != null) {
+                if (getter != null) {
+                    append(": ")
+                    append(getter.renderReturnType())
+                } else declaration.backingField?.type?.let { type ->
                     append(": ")
                     append(type.render())
                 }
@@ -367,10 +369,20 @@ class RenderIrElementVisitor(private val normalizeNames: Boolean = false) : IrEl
                     "name:$name visibility:$visibility modality:$modality " +
                     renderTypeParameters() + " " +
                     renderValueParameterTypes() + " " +
-                    "returnType:${returnType.render()} " +
+                    "returnType:${renderReturnType()} " +
                     renderSimpleFunctionFlags()
         }
 
+    private fun IrFunction.renderReturnType(): String =
+        safeReturnType?.render() ?: "<Uninitialized>"
+
+    private val IrFunction.safeReturnType: IrType?
+        get() = try {
+            returnType
+        } catch (e: ReturnTypeIsNotInitializedException) {
+            null
+        }
+
     private fun renderFlagsList(vararg flags: String?) =
         flags.filterNotNull().run {
             if (isNotEmpty())
@@ -407,7 +419,7 @@ class RenderIrElementVisitor(private val normalizeNames: Boolean = false) : IrEl
                     "visibility:$visibility " +
                     renderTypeParameters() + " " +
                     renderValueParameterTypes() + " " +
-                    "returnType:${returnType.render()} " +
+                    "returnType:${renderReturnType()} " +
                     renderConstructorFlags()
         }