Make difference between identifiers declared vs. used

[bartveneman]

For analyzing potential unused code it would be useful to know whether some 'variables' are either declared, used, both or none.

Container names

@container my-layout (inline-size: 100px) {}

main {
  container-name: my-layout;
  /* or shorthand */
  container: my-layout / inline-size;
}

.undeclared {
  container-name: i-dont-exist;
}

Custom properties

:root {
  --example: 1;
  column-count: var(--example);
}

.unused {
  --unused: 2;
}

.undeclared {
  column-count: var(--whoops);
}

.undeclared-fallback {
  column-count: var(--whoops, var(--whoopsie));
}