Gopls: Support for template files

Gopls provides some support for Go template files, that is, files that are parsed by text/template or html/template.

Enabling template support

Gopls recognizes template files based on their file extension, which may be configured by the templateExtensions setting. If this list is empty, template support is disabled. (This is the default value, since Go templates don’t have a canonical file extension.)

Additional configuration may be necessary to ensure that your client chooses the correct language kind when opening template files. Gopls recognizes both "tmpl" and "gotmpl" for template files. For example, in VS Code you will also need to add an entry to the files.associations mapping:

"files.associations": {
  ".mytemplate": "gotmpl"
},

Features

In template files, template support works inside the default {{ delimiters. (Go template parsing allows the user to specify other delimiters, but gopls does not know how to do that.)

Gopls template support includes the following features:

• Diagnostics: if template parsing returns an error, it is presented as a diagnostic. (Missing functions do not produce errors.)
• Syntax Highlighting: syntax highlighting is provided for template files.
• Definitions: gopls provides jump-to-definition inside templates, though it does not understand scoping (all templates are considered to be in one global scope).
• References: gopls provides find-references, with the same scoping limitation as definitions.
• Completions: gopls will attempt to suggest completions inside templates.

TODO: also

• Hover
• SemanticTokens
• Symbol search
• DocumentHighlight

The source files for this documentation can be found beneath golang.org/x/tools/gopls/doc.