1 //! lint on enum variants that are prefixed or suffixed by the same characters
3 use clippy_utils::camel_case;
4 use clippy_utils::diagnostics::{span_lint, span_lint_and_help};
5 use clippy_utils::source::is_present_in_source;
6 use rustc_ast::ast::{EnumDef, Item, ItemKind, VisibilityKind};
7 use rustc_lint::{EarlyContext, EarlyLintPass, Lint};
8 use rustc_session::{declare_tool_lint, impl_lint_pass};
9 use rustc_span::source_map::Span;
10 use rustc_span::symbol::Symbol;
12 declare_clippy_lint! {
13 /// **What it does:** Detects enumeration variants that are prefixed or suffixed
14 /// by the same characters.
16 /// **Why is this bad?** Enumeration variant names should specify their variant,
17 /// not repeat the enumeration name.
19 /// **Known problems:** None.
29 /// Could be written as:
37 pub ENUM_VARIANT_NAMES,
39 "enums where all variants share a prefix/postfix"
42 declare_clippy_lint! {
43 /// **What it does:** Detects public enumeration variants that are
44 /// prefixed or suffixed by the same characters.
46 /// **Why is this bad?** Public enumeration variant names should specify their variant,
47 /// not repeat the enumeration name.
49 /// **Known problems:** None.
59 /// Could be written as:
67 pub PUB_ENUM_VARIANT_NAMES,
69 "public enums where all variants share a prefix/postfix"
72 declare_clippy_lint! {
73 /// **What it does:** Detects type names that are prefixed or suffixed by the
74 /// containing module's name.
76 /// **Why is this bad?** It requires the user to type the module name twice.
78 /// **Known problems:** None.
83 /// struct BlackForestCake;
86 /// Could be written as:
89 /// struct BlackForest;
92 pub MODULE_NAME_REPETITIONS,
94 "type names prefixed/postfixed with their containing module's name"
97 declare_clippy_lint! {
98 /// **What it does:** Checks for modules that have the same name as their
101 /// **Why is this bad?** A typical beginner mistake is to have `mod foo;` and
102 /// again `mod foo { ..
104 /// The expectation is that items inside the inner `mod foo { .. }` are then
106 /// through `foo::x`, but they are only available through
108 /// If this is done on purpose, it would be better to choose a more
109 /// representative module name.
111 /// **Known problems:** None.
122 pub MODULE_INCEPTION,
124 "modules that have the same name as their parent module"
127 pub struct EnumVariantNames {
128 modules: Vec<(Symbol, String)>,
132 impl EnumVariantNames {
134 pub fn new(threshold: u64) -> Self {
142 impl_lint_pass!(EnumVariantNames => [
144 PUB_ENUM_VARIANT_NAMES,
145 MODULE_NAME_REPETITIONS,
149 /// Returns the number of chars that match from the start
151 fn partial_match(pre: &str, name: &str) -> usize {
152 let mut name_iter = name.chars();
153 let _ = name_iter.next_back(); // make sure the name is never fully matched
154 pre.chars().zip(name_iter).take_while(|&(l, r)| l == r).count()
157 /// Returns the number of chars that match from the end
159 fn partial_rmatch(post: &str, name: &str) -> usize {
160 let mut name_iter = name.chars();
161 let _ = name_iter.next(); // make sure the name is never fully matched
164 .zip(name_iter.rev())
165 .take_while(|&(l, r)| l == r)
170 cx: &EarlyContext<'_>,
174 item_name_chars: usize,
178 if (def.variants.len() as u64) < threshold {
181 for var in &def.variants {
182 let name = var.ident.name.as_str();
183 if partial_match(item_name, &name) == item_name_chars
184 && name.chars().nth(item_name_chars).map_or(false, |c| !c.is_lowercase())
185 && name.chars().nth(item_name_chars + 1).map_or(false, |c| !c.is_numeric())
187 span_lint(cx, lint, var.span, "variant name starts with the enum's name");
189 if partial_rmatch(item_name, &name) == item_name_chars {
190 span_lint(cx, lint, var.span, "variant name ends with the enum's name");
193 let first = &def.variants[0].ident.name.as_str();
194 let mut pre = &first[..camel_case::until(&*first)];
195 let mut post = &first[camel_case::from(&*first)..];
196 for var in &def.variants {
197 let name = var.ident.name.as_str();
199 let pre_match = partial_match(pre, &name);
200 pre = &pre[..pre_match];
201 let pre_camel = camel_case::until(pre);
202 pre = &pre[..pre_camel];
203 while let Some((next, last)) = name[pre.len()..].chars().zip(pre.chars().rev()).next() {
204 if next.is_numeric() {
207 if next.is_lowercase() {
208 let last = pre.len() - last.len_utf8();
209 let last_camel = camel_case::until(&pre[..last]);
210 pre = &pre[..last_camel];
216 let post_match = partial_rmatch(post, &name);
217 let post_end = post.len() - post_match;
218 post = &post[post_end..];
219 let post_camel = camel_case::from(post);
220 post = &post[post_camel..];
222 let (what, value) = match (pre.is_empty(), post.is_empty()) {
223 (true, true) => return,
224 (false, _) => ("pre", pre),
225 (true, false) => ("post", post),
231 &format!("all variants have the same {}fix: `{}`", what, value),
234 "remove the {}fixes and use full paths to \
235 the variants instead of glob imports",
242 fn to_camel_case(item_name: &str) -> String {
243 let mut s = String::new();
245 for c in item_name.chars() {
246 if c.is_uppercase() {
247 // we only turn snake case text into CamelCase
248 return item_name.to_string();
256 s.extend(c.to_uppercase());
264 impl EarlyLintPass for EnumVariantNames {
265 fn check_item_post(&mut self, _cx: &EarlyContext<'_>, _item: &Item) {
266 let last = self.modules.pop();
267 assert!(last.is_some());
270 #[allow(clippy::similar_names)]
271 fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
272 let item_name = item.ident.name.as_str();
273 let item_name_chars = item_name.chars().count();
274 let item_camel = to_camel_case(&item_name);
275 if !item.span.from_expansion() && is_present_in_source(cx, item.span) {
276 if let Some(&(ref mod_name, ref mod_camel)) = self.modules.last() {
277 // constants don't have surrounding modules
278 if !mod_camel.is_empty() {
279 if mod_name == &item.ident.name {
280 if let ItemKind::Mod(..) = item.kind {
285 "module has the same name as its containing module",
289 if item.vis.kind.is_pub() {
290 let matching = partial_match(mod_camel, &item_camel);
291 let rmatching = partial_rmatch(mod_camel, &item_camel);
292 let nchars = mod_camel.chars().count();
294 let is_word_beginning = |c: char| c == '_' || c.is_uppercase() || c.is_numeric();
296 if matching == nchars {
297 match item_camel.chars().nth(nchars) {
298 Some(c) if is_word_beginning(c) => span_lint(
300 MODULE_NAME_REPETITIONS,
302 "item name starts with its containing module's name",
307 if rmatching == nchars {
310 MODULE_NAME_REPETITIONS,
312 "item name ends with its containing module's name",
319 if let ItemKind::Enum(ref def, _) = item.kind {
320 let lint = match item.vis.kind {
321 VisibilityKind::Public => PUB_ENUM_VARIANT_NAMES,
322 _ => ENUM_VARIANT_NAMES,
324 check_variant(cx, self.threshold, def, &item_name, item_name_chars, item.span, lint);
326 self.modules.push((item.ident.name, item_camel));