Compatibility fix with Hydra 1.1

[omry]

One of the changes in Hydra 1.1 is that the default composition order is changing.
This is documented here.
In Hydra 1.1, a config is overriding values introduced by the defaults list while in Hydra 1.0 - the defaults list was overriding the values in the config.

fairseq is currently depending on the previous behavior:
The class FairseqConfig defines config values, and it's expecting them to be overridden by the defaults list.
This result in a different config being created when running fairseq_cli/hydra_train.py with Hydra 1.0 and with 1.1.

Hydra 1.1 introduced the _self_ keyword in the defaults list to control the composition order. In order to achieve the behavior of Hydra 1.0, _self_ should be added as the first item in the defaults list.

To allow for a smoother migration, Hydra 1.0 is ignoring _self_ starting from 1.0.7 (previous versions will issue an error).

This diff adds _self_ as the first item in the defaults list the fairseq config, and introduce a dependency a Hydra 1.0 version that is equal or newer to 1.0.7.

Testing:

I ensured that the following yield the same composed config:
Default config with Hydra 1.0.6, 1.0.7 and 1.1.0

examples/wav2vec/config/finetuning/base_10h.yaml with Hydra 1.0.6, 1.0.7 and 1.1.0.

This can be achieved by outputing the generated config using --cfg job and compating the outputs.

[omry]

This fails in some tests on Hydra 1.1 due to an OmegaConf 2.1 change making access to non existing fields behave like it does for objects and dicts (raises an exception).

[alexeib]

will this have any effect on external configs (--config-dir + --config-name)? if not lgtm

[omry]

Not supposed to.
As I said, I tested examples/wav2vec/config/finetuning/base_10h.yaml and it's composing the same config.

[omry]

@alexeib, can we get this merged soon?

[alexeib]

sure, can you just make diff from this? merging happens through fbcode, not here

[facebook-github-bot]

@jieru-hu has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[facebook-github-bot]

@jieru-hu merged this pull request in 53802e7.

[gegallego]

Hi! This line could be changed to hydra-core>=1.0.7,<=1.1, right?
Also, omegaconf requirement should then be changed to omegaconf<=2.1 to satisfy this requirement from hydra.

[rsxdalv]

@omry Could you please confirm if fairseq works with hydra-core==1.1?

[omry]

@rsxdalv, Nope. I am no longer involved with either.