Reflect convertible types in type comparison

[radeksimko]

Use-cases

Whenever we semantically highlight type-aware reference addresses, we compare types strictly (minus unknown/dynamic type which is handled as edge case).

Some types are however convertible to another, e.g. bool/number is convertible to string, as per https://www.terraform.io/docs/language/expressions/types.html#type-conversion

This leads e.g. to the following (valid config):

where var.test is not recognized as valid because access_token is expected to be string.

Proposal

• Recognize individual expressions when nested #496

hcl-lang

• Reflect convertible types when completing within expressions (such as when function returns number and is enclosed by something that expects string, or when any string-convertible type is used in template expression)
• Reflect convertible types when comparing origins and targets

Implementation Notes

The go-cty convert package contains the logic which is used by Terraform/HCL in this context:
https://pkg.go.dev/github.com/zclconf/[email protected]/cty/convert

[radeksimko]

We now consider "convertability" when comparing constraints with reference targets and function return types, as a result of various recent PRs (#1237, hashicorp/hcl-lang#232, hashicorp/hcl-lang#203, hashicorp/hcl-lang#199, hashicorp/hcl-lang#186, hashicorp/hcl-lang#185, hashicorp/hcl-lang#184) which are all part of the latest stable release v0.31.0.

The above example now works, i.e. var.test is recognised even though it's number in string constrained attribute.

Other future expressions will account for this individually when implemented, e.g. #529 will likely imply cty.Number constraint for either side of - or + and cty.Bool for ! etc. but in reality allow other primitive types in both cases, since they're convertible to that type.

Origin constraint type comparison is a question to follow-up on more generally as part of hashicorp/hcl-lang#269

[github-actions]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.
If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.