With https://github.com/zed-industries/zed/pull/6882 basic syntax
highlighting support for Terraform has arrived in Zed. To fully support
all features of the language server (when it lands), it's necessary to
handle `*.tfvars` slightly differently.
TL;DR: [terraform-ls](https://github.com/hashicorp/terraform-ls) expects
`terraform` as language id for `*.tf` files and `terraform-vars` as
language id for `*.tfvars` files because the allowed configuration
inside the files is different. Duplicating the Terraform language
configuration was the only way I could see to achieve this.
---
In the
[LSP](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocumentItem),
text documents have a language identifier to identify a document on the
server side to avoid reinterpreting the file extension.
The Terraform language server currently uses two different language
identifiers:
* `terraform` - for `*.tf` files
* `terraform-vars` - for `*.tfvars` files
Both file types contain HCL and can be highlighted using the same
grammar and tree-sitter configuration files. The difference in the file
content is that `*.tfvars` files only allow top-level attributes and no
blocks. [_So you could argue that `*.tfvars` can use a stripped down
version of the grammar_]. To set the right context (which affects
completion, hover, validation...) for each file, we need to send a
different language id.
The only way I could see to achieve this with the current architecture
was to copy the Terraform language configuration with a different `name`
and different `path_suffixes`. Everything else is the same.
A Terraform LSP adapter implementation would then map the language
configurations to their specific language ids:
```rust
fn language_ids(&self) -> HashMap<String, String> {
HashMap::from_iter([
("Terraform".into(), "terraform".into()),
("Terraform Vars".into(), "terraform-vars".into()),
])
}
```
I think it might be helpful in the future to have another way to map
file extensions to specific language ids without having to create a new
language configuration.
### UX Before
### UX After
Release Notes:
- N/A
---
* Part of https://github.com/zed-industries/zed/issues/5098
https://github.com/zed-industries/zed/pull/7467 introduced a new
`grammar` field in the language configuration files.
The underlying tree-sitter grammar for Terraform should be `hcl` instead
of `terraform`. This PR fixes that typo.
Release Notes:
- N/A
Daniel BanckandMax Brunsfeld