tree 885b98d6a26d8e0c13db05e07ce6bfab2c3fcfbc
parent 2814d697232b16071f02bbcd66ecba608092901e
author Ewout van Bekkum <ewout@google.com> 1668097362 +0000
committer CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com> 1668097362 +0000

pw_build/cmake: Enable separate backend variable declarations

Extends the CMake facade API to mirror GN in its ability to specify
facade backend variables separate from the facade library
declarations. Outside of making this more consistent with the GN
build, this also enables enable_if for unit tests in the future.

As part of this backend variables for facades are no longer set to
{NAME}.NO_BACKEND_SET by default and instead are set to empty
strings if unset.

Change-Id: Ie0669c702a15a462cef92d546ad28ca945b71027
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/117412
Pigweed-Auto-Submit: Ewout van Bekkum <ewout@google.com>
Commit-Queue: Ewout van Bekkum <ewout@google.com>
Reviewed-by: Wyatt Hepler <hepler@google.com>