Previously we were using the experimental HCL 2 repository, but now we'll
shift over to the v2 import path within the main HCL repository as part of
actually releasing HCL 2.0 as stable.
This is a mechanical search/replace to the new import paths. It also
switches to the v2.0.0 release of HCL, which includes some new code that
Terraform didn't previously have but should not change any behavior that
matters for Terraform's purposes.
For the moment the experimental HCL2 repository is still an indirect
dependency via terraform-config-inspect, so it remains in our go.sum and
vendor directories for the moment. Because terraform-config-inspect uses
a much smaller subset of the HCL2 functionality, this does still manage
to prune the vendor directory a little. A subsequent release of
terraform-config-inspect should allow us to completely remove that old
repository in a future commit.
This allows basic static validation of a traversal against a schema, to
verify that it represents a valid path through the structural parts of
the schema.
The main purpose of this is to produce better error messages (using our
knowledge of the schema) than we'd be able to achieve by just relying
on HCL expression evaluation errors. This is particularly important for
nested blocks because it may not be obvious whether one is represented
internally by a set or a list, and incorrect usage would otherwise produce
a confusing HCL-oriented error message.
Martin Atkins