Fix line number sometimes wrongly reported by no_tab_linter() (#134)

NEWS.md

@@ -1,4 +1,5 @@
 # lintr 1.0.0.9001 #
+* Fix line number sometimes wrongly reported by no_tab_linter() (#134, @fangly)
 * Fix line and column number sometimes wrongly reported by spaces_inside_linter()
   (#203, @fangly)
 * Add `pipe_continuation_linter()` (#216).
@@ -42,7 +43,8 @@
 * Fixed lint_package bug where cache was not caching (#146, @schloerke)
 * Fixed cache not saved in a directory other than requested (#213, @fangly)
 * Commas linter handles missing arguments calls properly (#145)
-* Add `function_left_parentheses_linter` to check that there is no space between a function name and its left parentheses (#204, @jrnold).
+* Add `function_left_parentheses_linter` to check that there is no space between
+  a function name and its left parentheses (#204, @jrnold).
 
 # lintr 1.0.0 #
 * bugfix to work with testthat 1.0.0

R/no_tab_linter.R

@@ -1,41 +1,41 @@
-#' @describeIn linters check that only spaces are used, never tabs.
+#' @describeIn linters check that only spaces are used for indentation, not tabs.
 #' @export
 no_tab_linter <- function(source_file) {
-  all_res <- re_matches(
+  all_matches <- re_matches(
     source_file$lines,
     rex(start, zero_or_more(regex("\\s")), one_or_more("\t")),
     locations = TRUE,
     global = TRUE
   )
-  names(all_res) <- as.character(seq_along(all_res))
-
-  # filter out lines with no matches
-  all_res <- all_res[
-    vapply(all_res, function(line_match) {!is.na(line_match[["start"]][[1L]])}, logical(1L))
-  ]
+  line_numbers <- as.integer(names(source_file$lines))
 
   Map(
-    function(line_res, line_num) {
+    function(line_matches, line_number) {
       lapply(
-        split(line_res, seq_len(nrow(line_res))),
-        function(res) {
+        split(line_matches, seq_len(nrow(line_matches))),
+        function(match) {
+          start <- match[["start"]]
+          if (is.na(start)) {
+            return()
+          }
+          end <- match[["end"]]
           Lint(
             filename = source_file$filename,
-            line_number = line_num,
-            column_number = res[["start"]],
+            line_number = line_number,
+            column_number = start,
             type = "style",
             message = "Use spaces to indent, not tabs.",
-            line = source_file$lines[line_num],
+            line = source_file$lines[[as.character(line_number)]],
 
             # R outputs tabs with 8 spaces
             # TODO: this is incorrect for embedded tabs, I am not going to fix it.
-            ranges = list(c(res[["start"]], res[["end"]])),
+            ranges = list(c(start, end)),
             linter = "no_tab_linter"
           )
         }
       )
     },
-    all_res,
-    names(all_res)
+    all_matches,
+    line_numbers
   )
 }

tests/testthat/test-no_tab_linter.R

@@ -10,7 +10,9 @@ test_that("returns the correct linting", {
 
   expect_lint("#\tblah", NULL, no_tab_linter)
 
-  expect_lint("\tblah", msg, no_tab_linter)
+  expect_lint("\tblah", c(message = msg, line_number = 1L), no_tab_linter)
 
-  expect_lint("\t\tblah", msg, no_tab_linter)
+  expect_lint("\n\t\tblah", c(message = msg, line_number = 2L), no_tab_linter)
+
+  # Note: no tests of column number since they are currently incorrect (tabs converted to 8 spaces)
 })