[jira] [Created] (GROOVY-10055) STC does not support self bounded types

["Damir Murat (Jira)" <ji...@apache.org>]

Damir Murat created GROOVY-10055:
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             Summary: STC does not support self bounded types
                 Key: GROOVY-10055
                 URL: https://issues.apache.org/jira/browse/GROOVY-10055
             Project: Groovy
          Issue Type: Improvement
          Components: Static compilation, Static Type Checker
    Affects Versions: 3.0.8
            Reporter: Damir Murat


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

{code}
public class PostgreSQLContainer<SELF extends PostgreSQLContainer<SELF>> extends JdbcDatabaseContainer<SELF>
{code}

where JdbcDatabaseContainer is declared as

{code}
public abstract class JdbcDatabaseContainer<SELF extends JdbcDatabaseContainer<SELF>> extends GenericContainer<SELF> implements LinkableContainer
{code}

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:

{code}
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();
{code}

Unfortunately, STC complains with several errors:

{code}
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
{code}

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



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