Support files with embedded HCL syntax (e.g. Markdown)

[dbanck]

Background

VS Code mostly makes the assumption that each file has a single language and based on that language it decides whether to

• highlight the file using a particular grammar
• send the file to the language server, to provide IntelliSense (e.g. completion or hover) for it

There are files which may embed HCL syntax in some ways, e.g. Markdown via code blocks such as ```hcl

Proposal

Enable syntax highlighting for Markdown files via grammar injection, e.g.

{
    "scopeName": "markdown.hcl.codeblock",
    "path": "./syntaxes/hcl.codeblock.tmLanguage.json",
    "injectTo": [
	    "text.html.markdown"
    ],
    "embeddedLanguages": {
	    "meta.embedded.block.hcl": "hcl"
    }
},

Related links

• https://code.visualstudio.com/api/language-extensions/syntax-highlight-guide#embedded-languages
• Support files with embedded Terraform syntax (e.g. Markdown or ERB) vscode-terraform#403

[FlorinAndrei]

This would be very useful.