true-false-symbol

Prefer the reserved literals TRUE/FALSE over the rebindable base symbols T/F.

T and F are ordinary base-R bindings, not reserved words — T <- FALSE is legal — so relying on them as boolean shorthand is fragile. The fix is withheld when the name resolves to a local binding, since that is the user’s own variable rather than the shorthand.

T and F used as boolean shorthand:

x <- T
y <- F

warning: true-false-symbol
 --> example.R:1:6
  |
1 | x <- T
  |      ^ use `TRUE` instead of `T`
  = help: `T`/`F` are rebindable; prefer the reserved literals.
warning: true-false-symbol
 --> example.R:2:6
  |
2 | y <- F
  |      ^ use `FALSE` instead of `F`
  = help: `T`/`F` are rebindable; prefer the reserved literals.

After applying the fix:

x <- TRUE
y <- FALSE