1# buck2 shims 2 3The `shim/` subtree helps the Meta-internal buck2 build system also work in the 4open-source repo. 5 6Shims are how open-source buck2 supports a [line 7like](https://github.com/pytorch/executorch/blob/50aa517549d10324147534d91d04a923b76421d6/kernels/optimized/targets.bzl#L1): 8 9``` 10load("@fbsource//xplat/executorch/build:runtime_wrapper.bzl", "runtime") 11``` 12 13In the open-source repo, `fbsource//xplat` (a Meta-internal root) doesn't exist. 14The `shim = shim` line in `../.buckconfig` tells buck2 to look in 15[`shim/xplat/executorch/build/runtime_wrapper.bzl`](https://github.com/pytorch/executorch/blob/main/shim/xplat/executorch/build/runtime_wrapper.bzl) 16instead. 17