Preface: for Groovy traits with fields, the Groovy compiler generates
synthetic "$Trait$FieldHelper" classes which posed several problems to
our class file reader, caused by the fact that the contents of the
InnerClasses attribute broke some assumptions about how names on the JVM
are formed and used.
For a trait named `A`, the Groovy compiler will additionally generate a
synthetic class file `A$Trait$FieldHelper` with the following in the
InnerClasses attribute:
InnerClasses:
public static #15= #2 of #14; //FieldHelper=class A$Trait$FieldHelper of class A
i.e. the simple name of the class is `FieldHelper`, the name of its
outer class is `A`, but the full internal name is `A$Trait$FieldHelper`,
which is surprising considering that the names are usually obtained by
separating the outer and inner names via the dollar sign.
Another detail is that in some usages of this synthetic class, the
InnerClasses attribute was missing at all. For example, if an empty
class `B` extends `A`, then there's no InnerClasses attribute in `B`'s
class file, which is surprising because we might decode the same name
differently depending on the class file we encounter it in.
In this change, we attempt to treat these synthetic classes as top-level
by refusing to read "invalid" InnerClasses attribute values (they are
not technically invalid because they still conform to JVMS), fixing the
problem of "unresolved supertypes" error which occurred when these
classes were used as supertypes in a class file in a dependency.
1) In ClassifierResolutionContext.mapInternalNameToClassId, do not use
the ad-hoc logic (copy-pasted from intellij-core) to determine class
id heuristically from the internal name. For $Trait$FieldHelper
classes this logic attempted to replace all dollar signs with dots,
which was semantically incorrect: dollars there were used as
synthetic characters, not as a separator between outer and inner
classes.
2) In isNotTopLevelClass (Other.kt), only consider "valid" InnerClasses
attribute values, where the full name of the class is obtained by
separating the outer name and the inner name with a dollar character.
This way, we'll be able to treat class files with invalid attribute
values as top-level and avoid breaking any other assumptions in the
class file loader.
3) In BinaryJavaClass.visitInnerClass, record all valid InnerClasses
attribute values present in the class file, not just those related to
the class in question itself. This is needed now because previously,
the removed heuristics (see p.1) transformed mentioned inner class
names to class ids correctly >99% of the time. Now that the
heuristics are gone, we'll use the information present in the class
file to map names correctly and predictably. According to JVMS, this
attribute should contain information about all inner classes
mentioned in the class file, and this is true at least for class
files produced by javac.
#KT-18592 Fixed
