In Prometheus, label values are treated as strings when used with the
`=` and `!=` operators, and as regular expressions when used with the
`=~` and `!~` operators.
Injecting and then highlighting all label values as regex leads to a
situation where entirely valid **string** label values containing regex
special characters are mistakenly parsed and highlighted as regex. This
results in syntax errors, causing labels to be highlighted incorrectly.
For example, in `foo{bar=~"[a-z]{1,3}"}`, `{` and `}` are regex special
characters, so regex highlighting is expected. However, in
`foo{path="/foo/{id}"}`, `{` and `}` are just part of the string and
have no special meaning, so the whole value should be highlighted as a
string.
Since 0.9, @lang syntax is still available as fallback but will soon be deprecated.
Because of that, new syntax should be adopted once 0.9 becomes the
baseline requirements for nvim-treesitter
- update health check
- update doc
