Cargo Features

[dependencies]
syntect-assets = { version = "0.23.6", default-features = false, features = ["regex-onig", "regex-fancy"] }
default = regex-onig

The regex-onig feature is set by default whenever syntect-assets is added without default-features = false somewhere in the dependency tree.

regex-onig default

You need to use one of these if you depend on syntect-assets as a library:
Use the "oniguruma" regex engine

Enables regex-onig of syntect

regex-fancy

Use the rust-only "fancy-regex" engine

Enables regex-fancy of syntect