Component used: Room
Version used: 2.2.3
Devices/Android versions reproduced on: n/a
Android Studio 3.5.3
Build #AI-191.8026.42.35.6010548, built on November 15, 2019
JRE: 1.8.0_202-release-1483-b49-5587405 amd64
JVM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
Linux 5.3.0-24-generic

Steps to Reproduce:

1. Import the attached project into Android Studio (tested on 3.5.3)

2. Attempt to build the InterfaceSuspend module

Expected Results: A clean build

Actual Results: A build error:

error: Bookstore_Impl is not abstract and does not override abstract method loadCategoryByTransaction(String,Continuation<? super Pair<Category,? extends List<Book>>>) in Bookstore
public final class Bookstore_Impl implements Bookstore {
^
1 error

Here, Bookstore is a Kotlin interface with a @Dao annotation, defining a concrete suspending function that calls two other functions that should get code-generated:

@Dao
interface Bookstore {
@Insert
suspend fun save(category: Category)

@Insert
suspend fun save(vararg books: Book)

suspend fun loadCategoryByTransaction(shortCode: String) =
_loadCategory(shortCode) to _loadBooksInCategory(shortCode)

@Query("SELECT * FROM categories WHERE shortCode = :shortCode")
suspend fun _loadCategory(shortCode: String): Category

@Query("SELECT * FROM books WHERE categoryShortCode = :shortCode")
suspend fun _loadBooksInCategory(shortCode: String): List<Book>
}

If you switch this to be an abstract class, it compiles (see the AbstractSuspend module). If you add @Transaction to the function on the interface, it compiles (see the InterfaceTransaction module), though there's a separate bug with that (to be filed shortly).

https://issuetracker.google.com/issues/120241587 indicates that this should work, so I am assuming that this is a bug and not an unsupported feature. :-)

Let me know if you need more details -- thanks!