[GROOVY-11010] Ambiguous method reference when expecting a SAM type

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: Static Type Checker

Language

groovy

• Assignee: Eric Milles
• Reporter: Thodoris Sotiropoulos
• Created: 13/Apr/23 15:27
• Updated: 18/Jan/24 20:23

Description

I have the following program

import java.util.function.*;


class Main {
  static final void test() {
    from(Main::m);
  }

  static <K, V> void from(Function<K, V> f) {}
  static <V> void from(Supplier<V> f) {}

  static int m(String x) { return 1; }
}

Actual behavior

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
test.groovy: 6: [Static type checking] - Reference to method is ambiguous. Cannot choose between [void Main#from(java.util.function.Supplier<V>), void Main#from(java.util.function.Function<K, V>)]
 @ line 6, column 5.
       from(Main::m);
       ^

1 error

Expected behavior

Compile successfully

Notes

Tested against master (commit: 5bcd83e0fde722971f97d479f1a4d6da6cd4aa5f)

Test case adapted from (Guava library)

import java.util.function.*;

class Main {
  static final void test() {
    com.google.common.cache.CacheLoader.from(Main::m);
  }
}

Issue Links

• is related to: GROOVY-10714 STC: Callable, Runnable, Serializable overload preference for functional argument (closure, lambda, etc.)
• is related to: GROOVY-7582 Closure to SAM coercion doesn't handle overloads with different SAM signatures
• is related to: GROOVY-9852 Result is already complete (IllegalStateException)
• is related to: GROOVY-9881 STC can't distinguish SAMs based on arity
• is related to: GROOVY-10905 Improve matching implicit arg closures to SAM types