Support deprecation info in Config

[ly015]

Motivation

Support deprecation information in Config. Users can add a field _deprecation_ into a config file, which will trigger a deprecation warning during calling Config.fromfile. Optionally, the warning information can include a path to the expected config file to replace the deprecated one.

Modification

• Add deprecation information support in config.py
• Add unittest

Use cases (Optional)

For example, if a config file old_config.py has been renamed to new_config.py. To avoid bc-breaking, we can create an old_config.py file with deprecation information as following:

_base_ = './new_config.py'
_deprecation_ = dict(expected='configs/new_config.py')

[codecov]

Codecov Report

Merging #1275 (fce2cb1) into master (44edcdd) will increase coverage by 0.00%.
The diff coverage is 77.77%.

❗ Current head fce2cb1 differs from pull request most recent head bb5f201. Consider uploading reports for the commit bb5f201 to get more accurate results

@@           Coverage Diff           @@
##           master    #1275   +/-   ##
=======================================
  Coverage   68.42%   68.43%           
=======================================
  Files         160      160           
  Lines       10610    10619    +9     
  Branches     1938     1941    +3     
=======================================
+ Hits         7260     7267    +7     
  Misses       2975     2975           
- Partials      375      377    +2     

Flag	Coverage Δ
unittests	68.43% <77.77%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
mmcv/image/photometric.py	99.27% <ø> (ø)
mmcv/ops/deform_conv.py	62.04% <ø> (ø)
mmcv/ops/fused_bias_leakyrelu.py	30.90% <ø> (ø)
mmcv/runner/hooks/ema.py	90.69% <ø> (ø)
mmcv/runner/hooks/evaluation.py	89.08% <ø> (ø)
mmcv/utils/registry.py	98.31% <ø> (ø)
mmcv/utils/config.py	90.10% <77.77%> (-0.29%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 44edcdd...bb5f201. Read the comment docs.

[ZwwWayne]

The modification LGTM. It would be better to also update the documentation thus the users could know it right after this PR.

[innerlee]

It would be great to provide a link to the related pr

[innerlee]

I'm not sure about the usecase. If a user uses the wrong config file in his/her own config, then how should he/she get the warning?

I see

[ly015]

It would be great to provide a link to the related pr

You mean adding a key to the _deprecatoin_ dict in the config file, like reference or url?

[innerlee]

Yes, the pr will be very helpful since its diff provides many live examples