tree 8a89bc9e4d5e53990b0b15ccc20374510b66594f
parent 76e4e423cae9063ee309dacc708695e721cd3f54
author juliexxia <juliexxia@google.com> 1560454748 -0700
committer Copybara-Service <copybara-worker@google.com> 1560454811 -0700

Don't allow ctx.split_attr to access starlark transitions attributes.

Currently the split_attr struct building logic does its own transition application outside of ConfigurationResolver#applyTransition. That means we don't do proper Starlark transition set up and tear down. split_attr is also broken with starlark attr transitions because it always keys splits on cpu (regardless of what they're actually keyed on).

This bug has shown itself through two symptoms:
(1) split_attr not keying on expected keys
(2) Starlark transitions sometimes throwing errors if its not properly set up (i.e. defaults not loaded so can't find and use default values of build settings). What's concerning about this symptom is that there's no logic around the split_attr building for printing these errors. That has to happen by calling StarlarkTransition#replayEvents. This method is only called in in ConfigurationResolver#applyTransition SO it would seem that transitions are maintaining state between split_attr building and configuration resolution which is probably (?) not great. Furthermore, these errors are only printing ~some~ of the time. So we're nondeterministically erroring out which is even more not great.

This CL prevents users from running into these two symptoms with a helpful error message. But both will require follow up.

PiperOrigin-RevId: 253084578