unreachable_code_linter {lintr}

Block unreachable code and comments following return statements

Description

Code after e.g. a return() or stop() or in deterministically false conditional loops like ⁠if (FALSE)⁠ can't be reached; typically this is vestigial code left after refactoring or sandboxing code, which is fine for exploration, but shouldn't ultimately be checked in. Comments meant for posterity should be placed before the final return().

Usage

unreachable_code_linter()

Tags

best_practices, readability

See Also

linters for a complete list of linters available in lintr.

Examples

# will produce lints
code_lines <- "f <- function() {\n  return(1 + 1)\n  2 + 2\n}"
writeLines(code_lines)
lint(
  text = code_lines,
  linters = unreachable_code_linter()
)

code_lines <- "f <- if (FALSE) {\n 2 + 2\n}"
writeLines(code_lines)
lint(
  text = code_lines,
  linters = unreachable_code_linter()
)

code_lines <- "f <- while (FALSE) {\n 2 + 2\n}"
writeLines(code_lines)
lint(
  text = code_lines,
  linters = unreachable_code_linter()
)

# okay
code_lines <- "f <- function() {\n  return(1 + 1)\n}"
writeLines(code_lines)
lint(
  text = code_lines,
  linters = unreachable_code_linter()
)

code_lines <- "f <- if (foo) {\n 2 + 2\n}"
writeLines(code_lines)
lint(
  text = code_lines,
  linters = unreachable_code_linter()
)

code_lines <- "f <- while (foo) {\n 2 + 2\n}"
writeLines(code_lines)
lint(
  text = code_lines,
  linters = unreachable_code_linter()
)