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.
In order to allow lazy evaluation of resource indexes, we can't index
resources immediately via GetResourceInstance. Change the evaluation to
always return whole Resources via GetResource, and index individual
instances during expression evaluation.
This will allow us to always check for invalid index errors rather than
returning an unknown value and ignoring it during apply.
By collecting information about the input variables during analysis, we
can return approximate type information for any references to those
variables in expressions.
Since Terraform 0.11 allowed maps of maps and lists of lists in certain
circumstances even though this was documented as forbidden, we
conservatively return collection types whose element types are unknown
here, which allows us to do shallow inference on them but will cause
us to get an incomplete result if any operations are performed on
elements of the list or map value.
Although we can't do fully-precise type inference with access only to a
single module's configuration, we can do some approximate inference using
some clues within the module along with our resource type schemas.
This depends on HCL's ability to pass through type information even if the
input values are unknown, mapping our partial input type information into
partial output type information by evaluating the same expressions.
This will allow us to do some upgrades that require dynamic analysis to
fully decide, by giving us three outcomes: needed, not needed, or unknown.
If it's unknown then that'll be our prompt to emit a warning for the user
to make a decision.
James Bardin