tree c8822b78f22e923497dde3be22cce413cf431729
parent 6778a05b4c4779c4be63ccf0a2431acc71164d64
author juliexxia <juliexxia@google.com> 1554827603 -0700
committer Copybara-Service <copybara-worker@google.com> 1554827711 -0700

Allow starlark transitions to read starlark-defined options.

Calculate and supply defaults for all read starlark options before transitions are applied. Future work includes:
- combining skyfunction calls for inputs and outputs of starlark transitions
- enforcing that BuildOptions.starlarkOptions will never hold default values (opposite of native options which always hold default values) in order to make BuildConfigurationWithDefault == BuildConfigurationWithNoValue
- Making sure BuildConfiguration properly reflects StarlarkOptions

Work towards #5574, #5577, #5578

RELNOTES: None.
PiperOrigin-RevId: 242681946