What happened to Groovy syntax highlighting?

Question

On Stack Overflow I have answered many questions about Spock and Geb, two Groovy test frameworks. For years, I have used <!-- language: lang-groovy --> in combination with indentation by four spaces. Now I found out this syntax is deprecated, but for other languages like Java it still works, as I can see in my old answers. They have not been migrated to ```java. So I have several questions:

1. Will there be automatic migration from tag-based code block syntax highlighting to backtick-based one without indentation?

2. Specifically for Groovy, syntax highlighting does not work at all anymore, no matter if I use any of

   • <!-- language: lang-groovy -->
   • <!-- language: groovy -->
   • ```lang-groovy
   • ```groovy

   Will this be fixed? How do I correctly activate Groovy syntax highlighting now? It is not a super exotic language but one of the most popular JVM languages.

---

Update: This seems to be related to the syntax highlighter migration from Prettify to highlight.js which seems to have happened yesterday. But according to the list of supported languages, Groovy is supported by highlight.js.

Answer 1

This has been "fixed". We still do not support the groovy language explicitly, but syntax autohighlighting should at least kick in for unrecognized lang-* language overrides (on sites that allow for it, such as Stack Overflow). Due to not officially supporting the groovy syntax, this may have unintended highlighting depending on what language highlight.js decides the code snippet is.

Answer 2

As of 2024, on Stack Overflow, this does not appear to work for either Markdown style code blocks or indented code blocks with a language "hinting" comment.

Note: I assume the reason Groovy was dropped, was due to the fact that Kotlin has replaced it in the Gradle/Android community.

Markdown style

```groovy
plugins {
  id 'java'
}

group 'org.example'
version '1.0-SNAPSHOT'

repositories {
  mavenCentral()
}

dependencies {
  testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.1'
  testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.8.1'
  implementation 'com.microsoft.playwright:playwright:1.44.0'
}

test {
  useJUnitPlatform()
}
```

Indented code block with hinting

<!-- language: lang-groovy -->

    plugins {
      id 'java'
    }
    
    group 'org.example'
    version '1.0-SNAPSHOT'
    
    repositories {
      mavenCentral()
    }
    
    dependencies {
      testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.1'
      testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.8.1'
    }
    
    test {
      useJUnitPlatform()
    }

They both renders as lang-none:

<pre class="lang-none s-code-block">
  <code>
    <!-- Code here -->
  </code>
</pre>

Research

I viewed the Stack Overflow highlight.js script:

https://cdn.sstatic.net/Js/highlightjs-loader.en.js

And I searched for "grmr_", and noticed that only 48 languages are supported.

The official highlight.js docs state:

Supported languages:

Note: The languages available will depend on how you’ve built or are included the library in your app. For example our default minified web build includes only ~40 popular languages. See Getting the Library and Importing the Library in the README for examples of how to load additional/specific languages.

The number ~40 coincides with the 48 languages that Stack Overflow supports:

• bash
• c, clojure, coffeescript, cpp, csharp, css
• dart, delphi
• erlang
• go
• haskell, http
• ini
• java, javascript, json, julia
• kotlin
• latex, less, lisp, lua
• makefile, markdown, matlab
• objectivec, ocaml
• perl, php, php_template, plaintext, protobuf, python
• r, ruby, rust
• scala, scheme, scss, shell, sql, swift
• typescript
• vbnet, vhdl
• xml
• yaml

Conclusion

So I am wondering why Stack Overflow can't build their own minified build with more supported languages?

---

Update

This kind of works, but only in a live preview; prior to submission. I assume it defaulted to bash because that was the first one in the list.

<!-- language: lang-groovy -->

    plugins {
      id 'java'
    }
    
    group 'org.example'
    version '1.0-SNAPSHOT'
    
    repositories {
      mavenCentral()
    }
    
    dependencies {
      testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.1'
      testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.8.1'
    }
    
    test {
      useJUnitPlatform()
    }

It renders as:

<pre class="lang-groovy s-code-block">
  <code data-highlighted="yes" class="hljs language-bash">
    <!-- Code here -->
  </code>
</pre>