Wildcard of field type, method return type and method parameters in conditional rules can't be referenced

[zerny]

When writing a conditional rule with a wildcard pattern in place of types in member patterns, it is not possible to back-reference it. It appears that the wildcard is simply skipped and subsequent wildcards are then off by one.

Consider the program:

package com.example;
public class A {
  public int foo() { ... }
  public int foo(int x) { ... }
}

The following rule will not work:

-if class **A { *** foo(); } -keep class <1>A { <2> foo(<2>); }

in contrast to:

-if class **A { *** foo(); } -keep class <1>A { int foo(int); }

Also, the following rule shows how the index is offset by one as it will apply and keep the one-arg foo if the zero-arg foo is used:

-if class **A { *** *(); } -keep class <1>A { int <2>(int); }

but the rule that would match the number of wildcards fails with an index error:

-if class **A { *** *(); } -keep class <1>A { int <3>(int); }

The same issue applies to:

• the return-type of fields as in { *** x; }
• the indexed method parameters as in { void foo(int, ***, int); }
• the "any" method parameters as in { void foo(...); }