Fix #8599: Emit trait init methods only as static methods. #10509
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smarter
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Nov 26, 2020
Concrete trait methods are encoded as two methods in the back-end: * a default method containing the real body, and * a static forwarder, to use for super calls (due to JVM reasons). Previously, we did that also for the trait initializer methods `$init$`. However, that causes unrelated default methods to be inherited by Scala classes that extend several traits. In turn, that prevents Java classes from extending such classes. Now, for the `$init$` methods, instead of creating a static forwarder, we *move* the entire body to a static method. Therefore, we only create a static method, and no default method. This corresponds to what scalac does as well (both what we do and how we do it), although the previous "discrepancy" was not causing any incompatibility between Scala 2 and 3 per se.
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Concrete trait methods are encoded as two methods in the back-end:
Previously, we did that also for the trait initializer methods
$init$. However, that causes unrelated default methods to be inherited by Scala classes that extend several traits. In turn, that prevents Java classes from extending such classes.Now, for the
$init$methods, instead of creating a static forwarder, we move the entire body to a static method. Therefore, we only create a static method, and no default method.This corresponds to what scalac does as well (both what we do and how we do it), although the previous "discrepancy" was not causing any incompatibility between Scala 2 and 3 per se.