Code generation error for using a protobuf value as map key

[psybers]

The code generation strategy for storing into a map is currently broken. If the key is complex and contains getting values from a protobuf field, it breaks. This is not a problem if the value being stored is a protobuf field, only if the key is.

Here is a simple test case to trigger the error:

o: output sum of int;
o << 1;

committers: map[string] of bool;

foreach (i: int; def(input.code_repositories[i]))
    committers[input.code_repositories[i].url] = true;

And here is the output:

Bug.java:140: error: illegal start of expression
___committers.put(_input.getCodeRepositoriesList().get(___i)).getUrl(, true);}
                                                                     ^