Provider-defined functions support

[dbanck]

Background

Terraform will introduce provider-defined functions in an upcoming release. This will allow provider authors to ship their own functions. Practitioners will be able to use them in their Terraform configuration using a new function call syntax: provider::aws::noop().

We currently support all built-in core functions as static definitions in terraform-schema. The provider functions will be part of the provider schema JSON and should be parsed whenever we get a provider schema (bundled or via CLI). Both need to be merged into a single list of function signatures.

Expected User Experience

Syntax highlighting, completion, hover, semantic tokens, and signature help are working as expected for provider-defined functions.

Proposal

hcl

• Fix NameRange for FunctionCallExpr
  • Wrong NameRange for namespaced function call expressions hcl#650

hcl-lang

• Stability improvement for nil expressions
  • In the earlydecoder -> PR
  • In the decoder package -> PR
• feat: support namespaced functions hcl-lang#372

terraform-json

• Initial support for provider-defined functions from providers schema -json terraform-json#119

terraform-schema

• Add support for provider-defined functions terraform-schema#320 -> PR

terraform-ls

• Replace coreFunctions with the new functions merger terraform-ls#1613 -> PR

syntax

• Support provider-defined functions syntax syntax#98 -> PR

---

Stretch Goals

• Completions: Recover partially typed provider defined functions after the first colon has been typed #1697

[ansgarm]

Posting my findings about the earlydecoder output stuff that is causing nil panics here:
The value of outputs seems to indeed be used, well to be precise, its type is:
https://github.com/hashicorp/terraform-schema/blob/0c03703f91f7085f9f2910e7e79f214c9f913ad0/schema/module_schema.go#L159

The value itself is also stored in a map, but that one is never read.

So, I don't think we can remove the handling there, but we can ignore nil expressions.

[dbanck]

Shipped 🎉

[github-actions]

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