Context: Issue 20012 - export inside mixin doesn't seem to work
By parsing all .d files in all 1584 currently registered and available git repositories on Dub using libdparse, it was found that 13 packages have a LinkageAttribute inside a MixinTemplateDeclaration. The total number of mixin templates is 1497. Note: libdparse crashed on dmd's test suite, so dmd was skipped, but that shoudln't be important. Below is an overview for each package why extern() is used, with a link to one of the instances where it's used: