Confusing error reporting while parsing a nested pass pipeline

[shabalind]

I'm currently working on a project that invokes an MLIR pass pipeline using Python bindings:

mypm = pm.PassManager.parse(f"""builtin.module(
    mypass1,
    func.func(mypass2,mypass3)
)""")

Somewhat surprisingly this pass pipeline is not valid according to the pipeline parser, it tells me to add , at the end after func.func(...). At the same time if you do add that comma, it errors as well since there is no valid pass name after the comma.

As a workaround I added a dummy pass that does nothing just to make it happy:

mypm = pm.PassManager.parse(f"""builtin.module(
    mypass1,
    func.func(mypass2,mypass3),
    dummy-do-nothing-pass
)""")

It would be great if this was not necessary in the first place, and parser accepted the initial snippet right away.

[llvmbot]

@llvm/issue-subscribers-mlir-core

[llvmbot]

@llvm/issue-subscribers-bug

[boschmitt]

@River707 you can close this issue, the commit fixes it (Poor choice of wording on my part, but I was unsure how the info in the review process would land in the commit)

[shabalind]

@boschmitt Thanks for the fix!