Go 1.19's "fmt" has some awareness of the new doc comment formatting
conventions and adjusts the presentation of the source comments to make
it clearer how godoc would interpret them. Therefore this commit includes
various updates made by "go fmt" to acheve that.
In line with our usual convention that we make stylistic/grammar/spelling
tweaks typically only when we're "in the area" changing something else
anyway, I also took this opportunity to review most of the comments that
this updated to see if there were any other opportunities to improve them.
Combine all plan-time graphs into a single graph builder, because
_everything is a plan_!
Convert the import graph to a plan graph. This should resolve a few edge
cases about things not being properly evaluated during import, and takes
a step towards being able to _plan_ an import.
Data sources should not require reading the previous versions. While we
previously skipped the decoding if it were to fail, this removes the
need for any prior state at all.
The only place where the prior state was functionally used was in the
destroy path. Because a data source destroy is only for cleanup purposes
to clean out the state using the same code paths as a managed resource,
we can substitute the prior state in the change change with a null value
to maintain the same behavior.
Data sources do not have state migrations, so there may be no way to
decode the prior state when faced with incompatible type changes.
Because prior state is only informational to the plan, and its existence
should not effect the planning process, we can skip decoding when faced
with errors.
Error messages for preconditions, postconditions, and custom variable
validations have until now been string literals. This commit changes
this to treat the field as an HCL expression, which must evaluate to a
string. Most commonly this will either be a string literal or a template
expression.
When the check rule condition is evaluated, we also evaluate the error
message. This means that the error message should always evaluate to a
string value, even if the condition passes. If it does not, this will
result in an error diagnostic.
If the condition fails, and the error message also fails to evaluate, we
fall back to a default error message. This means that the check rule
failure will still be reported, alongside diagnostics explaining why the
custom error message failed to render.
As part of this change, we also necessarily remove the heuristic about
the error message format. This guidance can be readded in future as part
of a configuration hint system.
If a resource or output value has a precondition or postcondition rule
then anything the condition depends on is a dependency of the object,
because the condition rules will be evaluated as part of visiting the
relevant graph node.
This is part of a general effort to move all of Terraform's non-library
package surface under internal in order to reinforce that these are for
internal use within Terraform only.
If you were previously importing packages under this prefix into an
external codebase, you could pin to an earlier release tag as an interim
solution until you've make a plan to achieve the same functionality some
other way.
