Problem

This repo demonstrates a problem with dead-code elimination in JIT watch mode.

Reproduction steps

1. Run npm install
2. Run NODE_ENV=development npx postcss ./styles.css -o ./compiled.css -w
3. Observe that compiled.css contains .bg-red-500
4. In index.html, remove the bg-red-500 class

Expected

The .bg-red-500 class is removed from compiled.css.

Actual

compiled.css does not change.

Comments

index.html is the only source file that references bg-red-500 (indeed, it's the only source file period). Therefore, I expect that removing that class from index.html would would remove it from the compiled css. However, there must be some caching that keeps it around. In most cases it isn't a problem to have extra style definitions in the compiled CSS, but it runs counter to the advertised property that with the JIT, your development CSS is exactly the same as your production CSS.