1 use clippy_utils::diagnostics::span_lint_and_sugg;
3 use rustc_errors::Applicability;
4 use rustc_lint::{EarlyContext, EarlyLintPass};
5 use rustc_session::{declare_lint_pass, declare_tool_lint};
6 use rustc_span::source_map::{BytePos, Span};
7 use std::convert::TryFrom;
10 /// **What it does:** Checks doc comments for usage of tab characters.
12 /// **Why is this bad?** The rust style-guide promotes spaces instead of tabs for indentation.
13 /// To keep a consistent view on the source, also doc comments should not have tabs.
14 /// Also, explaining ascii-diagrams containing tabs can get displayed incorrectly when the
15 /// display settings of the author and reader differ.
17 /// **Known problems:** None.
22 /// /// Struct to hold two strings:
25 /// pub struct DoubleString {
27 /// /// - First String:
28 /// /// - needs to be inside here
29 /// first_string: String,
31 /// /// - Second String:
32 /// /// - needs to be inside here
33 /// second_string: String,
37 /// Will be converted to:
40 /// /// Struct to hold two strings:
43 /// pub struct DoubleString {
45 /// /// - First String:
46 /// /// - needs to be inside here
47 /// first_string: String,
49 /// /// - Second String:
50 /// /// - needs to be inside here
51 /// second_string: String,
54 pub TABS_IN_DOC_COMMENTS,
56 "using tabs in doc comments is not recommended"
59 declare_lint_pass!(TabsInDocComments => [TABS_IN_DOC_COMMENTS]);
61 impl TabsInDocComments {
62 fn warn_if_tabs_in_doc(cx: &EarlyContext<'_>, attr: &ast::Attribute) {
63 if let ast::AttrKind::DocComment(_, comment) = attr.kind {
64 let comment = comment.as_str();
66 for (lo, hi) in get_chunks_of_tabs(&comment) {
67 // +3 skips the opening delimiter
68 let new_span = Span::new(
69 attr.span.lo() + BytePos(3 + lo),
70 attr.span.lo() + BytePos(3 + hi),
77 "using tabs in doc comments is not recommended",
78 "consider using four spaces per tab",
79 " ".repeat((hi - lo) as usize),
80 Applicability::MaybeIncorrect,
87 impl EarlyLintPass for TabsInDocComments {
88 fn check_attribute(&mut self, cx: &EarlyContext<'_>, attribute: &ast::Attribute) {
89 Self::warn_if_tabs_in_doc(cx, &attribute);
94 /// scans the string for groups of tabs and returns the start(inclusive) and end positions
95 /// (exclusive) of all groups
96 /// e.g. "sd\tasd\t\taa" will be converted to [(2, 3), (6, 8)] as
99 fn get_chunks_of_tabs(the_str: &str) -> Vec<(u32, u32)> {
100 let line_length_way_to_long = "doc comment longer than 2^32 chars";
101 let mut spans: Vec<(u32, u32)> = vec![];
102 let mut current_start: u32 = 0;
104 // tracker to decide if the last group of tabs is not closed by a non-tab character
105 let mut is_active = false;
107 let char_indices: Vec<_> = the_str.char_indices().collect();
109 if let [(_, '\t')] = char_indices.as_slice() {
113 for entry in char_indices.windows(2) {
115 [(_, '\t'), (_, '\t')] => {
116 // either string starts with double tab, then we have to set it active,
117 // otherwise is_active is true anyway
120 [(_, _), (index_b, '\t')] => {
121 // as ['\t', '\t'] is excluded, this has to be a start of a tab group,
122 // set indices accordingly
124 current_start = u32::try_from(*index_b).unwrap();
126 [(_, '\t'), (index_b, _)] => {
127 // this now has to be an end of the group, hence we have to push a new tuple
129 spans.push((current_start, u32::try_from(*index_b).unwrap()));
135 // only possible when tabs are at the end, insert last group
139 u32::try_from(char_indices.last().unwrap().0 + 1).expect(line_length_way_to_long),
147 mod tests_for_get_chunks_of_tabs {
148 use super::get_chunks_of_tabs;
151 fn test_unicode_han_string() {
152 let res = get_chunks_of_tabs(" \u{4f4d}\t");
154 assert_eq!(res, vec![(4, 5)]);
158 fn test_empty_string() {
159 let res = get_chunks_of_tabs("");
161 assert_eq!(res, vec![]);
166 let res = get_chunks_of_tabs("sd\t\t\taa");
168 assert_eq!(res, vec![(2, 5)]);
173 let res = get_chunks_of_tabs("\t\t");
175 assert_eq!(res, vec![(0, 2)]);
179 fn test_only_one_t() {
180 let res = get_chunks_of_tabs("\t");
182 assert_eq!(res, vec![(0, 1)]);
187 let res = get_chunks_of_tabs("sd\tasd\t\taa");
189 assert_eq!(res, vec![(2, 3), (6, 8)]);
194 let res = get_chunks_of_tabs("\t\taa");
196 assert_eq!(res, vec![(0, 2)]);
201 let res = get_chunks_of_tabs("aa\t\t");
203 assert_eq!(res, vec![(2, 4)]);
207 fn test_start_single() {
208 let res = get_chunks_of_tabs("\taa");
210 assert_eq!(res, vec![(0, 1)]);
214 fn test_end_single() {
215 let res = get_chunks_of_tabs("aa\t");
217 assert_eq!(res, vec![(2, 3)]);
222 let res = get_chunks_of_tabs("dsfs");
224 assert_eq!(res, vec![]);