When generating for CPP target, .srcjar is an inappropriate output artifact

[jondo2010]

Would be great to just generate the individual outputs into genfiles instead.

[marcohu]

That is not an option because the output depends on quite a few variables and it seems like too much effort to implement the analysis in Skylark.

I was not aware that .srcjar is not a general Bazel concept, but specific to Java. There might be an alternative that works across different languages though. I'll look into it.

[marcohu]

@jondo2010 Unfortunately there currently is no uniform way to feed rules with output that is not known at analysis phase. Some rules support archives, but not C++ and it probably won't be added. But an alternative is coming and seems to be nearly ready (for C++ at least).

In the meantime I propose the following workaround that should support most use cases: specify the generated files in the BUILD file. It's a bit cumbersome but as the filenames usually don't change often, it should be sufficient until Bazel has matured.

It would look like this:

antlr4(
    name = "generated",
    srcs = ["src/antlr4/Hello.g4"],
    language = "Cpp",
    output = [
        "HelloParser.h",
        "HelloLexer.tokens",
        "HelloBaseListener.h",
        "Hello.tokens",
        "HelloParser.cpp",
        "HelloLexer.cpp",
        "HelloLexer.h",
        "HelloLexer.interp",
        "HelloListener.h",
        "HelloBaseListener.cpp",
        "Hello.interp",
        "HelloListener.cpp"
    ],
)

To make things a bit easier, the rule could print the list of generated files that one can copy&paste in the BUILD file. So initially you would specify some random output and invoke the antlr rule to gain the actual list for inclusion.

Does that sound viable?