[GROOVY-10055] STC does not support self bounded types

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.8
• Fix Version/s: 4.0.0-beta-2, 3.0.20
• Component/s: Static compilation, Static Type Checker
• Assignee: Eric Milles
• Reporter: Damir Murat
• Created: 24/Apr/21 07:32
• Updated: 24/Oct/23 15:30
• Resolved: 18/Oct/21 18:19

Description

Some popular libraries use self bounded types for creating builder hierarchies. For example,
PostgreSQLContainer (from Tescontainers library) is declared as

public class PostgreSQLContainer<SELF extends PostgreSQLContainer<SELF>> extends JdbcDatabaseContainer<SELF>

where JdbcDatabaseContainer is declared as

public abstract class JdbcDatabaseContainer<SELF extends JdbcDatabaseContainer<SELF>> extends GenericContainer<SELF> implements LinkableContainer

and so on.

In the following example (tested with Groovy Console), I'm trying to create and modify such an object with its corresponding fluent API:

import org.testcontainers.containers.PostgreSQLContainer
import groovy.transform.CompileStatic

@Grab("org.testcontainers:testcontainers:1.15.3")
@Grab("org.testcontainers:postgresql:1.15.3")
@CompileStatic
class TestcontainersTester {
  static void testSome() {
    PostgreSQLContainer postgresqlServer = new PostgreSQLContainer<>()
        .withExposedPorts(5432)
        .withEnv(["TZ": "Europe/Paris"])
        .withDatabaseName("my_database")
        .withUsername("user")
        .withPassword("pass")

// Working alternative 1
//    PostgreSQLContainer postgresqlServer = new PostgreSQLContainer<PostgreSQLContainer<PostgreSQLContainer<PostgreSQLContainer<PostgreSQLContainer>>>>()
//        .withExposedPorts(5432)
//        .withEnv(["TZ": "Europe/Paris"])
//        .withDatabaseName("my_database")
//        .withUsername("user")
//        .withPassword("pass")

// Working alternative 2
//    PostgreSQLContainer postgresqlServer = new PostgreSQLContainer<>()
//    postgresqlServer.withExposedPorts(5432)
//    postgresqlServer.withEnv(["TZ": "Europe/Paris"])
//    postgresqlServer.withDatabaseName("my_database")
//    postgresqlServer.withUsername("user")
//    postgresqlServer.withPassword("pass")

    println postgresqlServer
  }
}

TestcontainersTester.testSome();

Unfortunately, STC complains with several errors:

4 compilation errors:

[Static type checking] - Cannot call SELF#withEnv(java.util.Map <java.lang.String, java.lang.String>) with arguments [java.util.LinkedHashMap <java.lang.String, java.lang.String>] 
 at line: 11, column: 17

[Static type checking] - Cannot find matching method java.lang.Object#withDatabaseName(java.lang.String). Please check if the declared type is correct and if the method exists.
 at line: 12, column: 26

[Static type checking] - Cannot find matching method java.lang.Object#withUsername(java.lang.String). Please check if the declared type is correct and if the method exists.
 at line: 13, column: 22

[Static type checking] - Cannot find matching method java.lang.Object#withPassword(java.lang.String). Please check if the declared type is correct and if the method exists.
 at line: 9, column: 44

There are two working alternatives in the example. "Alternative 1" is not really practical, but maybe it can help with solving the issue. "Alternative 2" is an actual practical workaround that can be further improved by using the "with" method.

Tnx

Issue Links

• fixes: GROOVY-7690 TypeChecked Groovy does not throw illegal assignment error at compile time when using raw generic type
• relates to: GROOVY-10619 STC: fix support for unbounded wildcard references to self-bounded type parameters
• relates to: GROOVY-10868 Cannot find matching method when using generics