]>
Commit | Line | Data |
---|---|---|
ea8adc8c XL |
1 | //! checks for attributes |
2 | ||
3 | use reexport::*; | |
4 | use rustc::lint::*; | |
5 | use rustc::hir::*; | |
6 | use rustc::ty::{self, TyCtxt}; | |
7 | use semver::Version; | |
2c00a5a8 | 8 | use syntax::ast::{Attribute, AttrStyle, Lit, LitKind, MetaItemKind, NestedMetaItem, NestedMetaItemKind}; |
ea8adc8c | 9 | use syntax::codemap::Span; |
abe05a73 | 10 | use utils::{in_macro, match_def_path, opt_def_id, paths, snippet_opt, span_lint, span_lint_and_then}; |
ea8adc8c XL |
11 | |
12 | /// **What it does:** Checks for items annotated with `#[inline(always)]`, | |
13 | /// unless the annotated function is empty or simply panics. | |
14 | /// | |
15 | /// **Why is this bad?** While there are valid uses of this annotation (and once | |
16 | /// you know when to use it, by all means `allow` this lint), it's a common | |
17 | /// newbie-mistake to pepper one's code with it. | |
18 | /// | |
19 | /// As a rule of thumb, before slapping `#[inline(always)]` on a function, | |
20 | /// measure if that additional function call really affects your runtime profile | |
21 | /// sufficiently to make up for the increase in compile time. | |
22 | /// | |
23 | /// **Known problems:** False positives, big time. This lint is meant to be | |
24 | /// deactivated by everyone doing serious performance work. This means having | |
25 | /// done the measurement. | |
26 | /// | |
27 | /// **Example:** | |
28 | /// ```rust | |
29 | /// #[inline(always)] | |
30 | /// fn not_quite_hot_code(..) { ... } | |
31 | /// ``` | |
32 | declare_lint! { | |
33 | pub INLINE_ALWAYS, | |
34 | Warn, | |
35 | "use of `#[inline(always)]`" | |
36 | } | |
37 | ||
38 | /// **What it does:** Checks for `extern crate` and `use` items annotated with | |
39 | /// lint attributes | |
40 | /// | |
41 | /// **Why is this bad?** Lint attributes have no effect on crate imports. Most | |
42 | /// likely a `!` was | |
43 | /// forgotten | |
44 | /// | |
45 | /// **Known problems:** Technically one might allow `unused_import` on a `use` | |
46 | /// item, | |
47 | /// but it's easier to remove the unused item. | |
48 | /// | |
49 | /// **Example:** | |
50 | /// ```rust | |
51 | /// #[deny(dead_code)] | |
52 | /// extern crate foo; | |
53 | /// #[allow(unused_import)] | |
54 | /// use foo::bar; | |
55 | /// ``` | |
56 | declare_lint! { | |
57 | pub USELESS_ATTRIBUTE, | |
58 | Warn, | |
59 | "use of lint attributes on `extern crate` items" | |
60 | } | |
61 | ||
62 | /// **What it does:** Checks for `#[deprecated]` annotations with a `since` | |
63 | /// field that is not a valid semantic version. | |
64 | /// | |
65 | /// **Why is this bad?** For checking the version of the deprecation, it must be | |
66 | /// a valid semver. Failing that, the contained information is useless. | |
67 | /// | |
68 | /// **Known problems:** None. | |
69 | /// | |
70 | /// **Example:** | |
71 | /// ```rust | |
72 | /// #[deprecated(since = "forever")] | |
73 | /// fn something_else(..) { ... } | |
74 | /// ``` | |
75 | declare_lint! { | |
76 | pub DEPRECATED_SEMVER, | |
77 | Warn, | |
78 | "use of `#[deprecated(since = \"x\")]` where x is not semver" | |
79 | } | |
80 | ||
2c00a5a8 XL |
81 | /// **What it does:** Checks for empty lines after outer attributes |
82 | /// | |
83 | /// **Why is this bad?** | |
84 | /// Most likely the attribute was meant to be an inner attribute using a '!'. | |
85 | /// If it was meant to be an outer attribute, then the following item | |
86 | /// should not be separated by empty lines. | |
87 | /// | |
88 | /// **Known problems:** None | |
89 | /// | |
90 | /// **Example:** | |
91 | /// ```rust | |
92 | /// // Bad | |
93 | /// #[inline(always)] | |
94 | /// | |
95 | /// fn not_quite_good_code(..) { ... } | |
96 | /// | |
97 | /// // Good (as inner attribute) | |
98 | /// #![inline(always)] | |
99 | /// | |
100 | /// fn this_is_fine(..) { ... } | |
101 | /// | |
102 | /// // Good (as outer attribute) | |
103 | /// #[inline(always)] | |
104 | /// fn this_is_fine_too(..) { ... } | |
105 | /// ``` | |
106 | declare_lint! { | |
107 | pub EMPTY_LINE_AFTER_OUTER_ATTR, | |
108 | Warn, | |
109 | "empty line after outer attribute" | |
110 | } | |
111 | ||
ea8adc8c XL |
112 | #[derive(Copy, Clone)] |
113 | pub struct AttrPass; | |
114 | ||
115 | impl LintPass for AttrPass { | |
116 | fn get_lints(&self) -> LintArray { | |
2c00a5a8 | 117 | lint_array!(INLINE_ALWAYS, DEPRECATED_SEMVER, USELESS_ATTRIBUTE, EMPTY_LINE_AFTER_OUTER_ATTR) |
ea8adc8c XL |
118 | } |
119 | } | |
120 | ||
121 | impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AttrPass { | |
122 | fn check_attribute(&mut self, cx: &LateContext<'a, 'tcx>, attr: &'tcx Attribute) { | |
123 | if let Some(ref items) = attr.meta_item_list() { | |
124 | if items.is_empty() || attr.name().map_or(true, |n| n != "deprecated") { | |
125 | return; | |
126 | } | |
127 | for item in items { | |
abe05a73 XL |
128 | if_chain! { |
129 | if let NestedMetaItemKind::MetaItem(ref mi) = item.node; | |
130 | if let MetaItemKind::NameValue(ref lit) = mi.node; | |
131 | if mi.name() == "since"; | |
132 | then { | |
133 | check_semver(cx, item.span, lit); | |
134 | } | |
135 | } | |
ea8adc8c XL |
136 | } |
137 | } | |
138 | } | |
139 | ||
140 | fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) { | |
141 | if is_relevant_item(cx.tcx, item) { | |
142 | check_attrs(cx, item.span, &item.name, &item.attrs) | |
143 | } | |
144 | match item.node { | |
abe05a73 | 145 | ItemExternCrate(_) | ItemUse(_, _) => { |
ea8adc8c XL |
146 | for attr in &item.attrs { |
147 | if let Some(ref lint_list) = attr.meta_item_list() { | |
148 | if let Some(name) = attr.name() { | |
149 | match &*name.as_str() { | |
150 | "allow" | "warn" | "deny" | "forbid" => { | |
151 | // whitelist `unused_imports` and `deprecated` | |
152 | for lint in lint_list { | |
153 | if is_word(lint, "unused_imports") || is_word(lint, "deprecated") { | |
154 | if let ItemUse(_, _) = item.node { | |
155 | return; | |
156 | } | |
157 | } | |
158 | } | |
159 | if let Some(mut sugg) = snippet_opt(cx, attr.span) { | |
160 | if sugg.len() > 1 { | |
161 | span_lint_and_then( | |
162 | cx, | |
163 | USELESS_ATTRIBUTE, | |
164 | attr.span, | |
165 | "useless lint attribute", | |
166 | |db| { | |
167 | sugg.insert(1, '!'); | |
168 | db.span_suggestion( | |
169 | attr.span, | |
170 | "if you just forgot a `!`, use", | |
171 | sugg, | |
172 | ); | |
173 | }, | |
174 | ); | |
175 | } | |
176 | } | |
177 | }, | |
178 | _ => {}, | |
179 | } | |
180 | } | |
181 | } | |
182 | } | |
183 | }, | |
184 | _ => {}, | |
185 | } | |
186 | } | |
187 | ||
188 | fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx ImplItem) { | |
189 | if is_relevant_impl(cx.tcx, item) { | |
190 | check_attrs(cx, item.span, &item.name, &item.attrs) | |
191 | } | |
192 | } | |
193 | ||
194 | fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx TraitItem) { | |
195 | if is_relevant_trait(cx.tcx, item) { | |
196 | check_attrs(cx, item.span, &item.name, &item.attrs) | |
197 | } | |
198 | } | |
199 | } | |
200 | ||
201 | fn is_relevant_item(tcx: TyCtxt, item: &Item) -> bool { | |
202 | if let ItemFn(_, _, _, _, _, eid) = item.node { | |
203 | is_relevant_expr(tcx, tcx.body_tables(eid), &tcx.hir.body(eid).value) | |
204 | } else { | |
2c00a5a8 | 205 | true |
ea8adc8c XL |
206 | } |
207 | } | |
208 | ||
209 | fn is_relevant_impl(tcx: TyCtxt, item: &ImplItem) -> bool { | |
210 | match item.node { | |
211 | ImplItemKind::Method(_, eid) => is_relevant_expr(tcx, tcx.body_tables(eid), &tcx.hir.body(eid).value), | |
212 | _ => false, | |
213 | } | |
214 | } | |
215 | ||
216 | fn is_relevant_trait(tcx: TyCtxt, item: &TraitItem) -> bool { | |
217 | match item.node { | |
218 | TraitItemKind::Method(_, TraitMethod::Required(_)) => true, | |
219 | TraitItemKind::Method(_, TraitMethod::Provided(eid)) => { | |
220 | is_relevant_expr(tcx, tcx.body_tables(eid), &tcx.hir.body(eid).value) | |
221 | }, | |
222 | _ => false, | |
223 | } | |
224 | } | |
225 | ||
226 | fn is_relevant_block(tcx: TyCtxt, tables: &ty::TypeckTables, block: &Block) -> bool { | |
227 | if let Some(stmt) = block.stmts.first() { | |
228 | match stmt.node { | |
229 | StmtDecl(_, _) => true, | |
abe05a73 | 230 | StmtExpr(ref expr, _) | StmtSemi(ref expr, _) => is_relevant_expr(tcx, tables, expr), |
ea8adc8c XL |
231 | } |
232 | } else { | |
abe05a73 XL |
233 | block |
234 | .expr | |
235 | .as_ref() | |
236 | .map_or(false, |e| is_relevant_expr(tcx, tables, e)) | |
ea8adc8c XL |
237 | } |
238 | } | |
239 | ||
240 | fn is_relevant_expr(tcx: TyCtxt, tables: &ty::TypeckTables, expr: &Expr) -> bool { | |
241 | match expr.node { | |
242 | ExprBlock(ref block) => is_relevant_block(tcx, tables, block), | |
243 | ExprRet(Some(ref e)) => is_relevant_expr(tcx, tables, e), | |
abe05a73 XL |
244 | ExprRet(None) | ExprBreak(_, None) => false, |
245 | ExprCall(ref path_expr, _) => if let ExprPath(ref qpath) = path_expr.node { | |
246 | if let Some(fun_id) = opt_def_id(tables.qpath_def(qpath, path_expr.hir_id)) { | |
ea8adc8c XL |
247 | !match_def_path(tcx, fun_id, &paths::BEGIN_PANIC) |
248 | } else { | |
249 | true | |
250 | } | |
abe05a73 XL |
251 | } else { |
252 | true | |
ea8adc8c XL |
253 | }, |
254 | _ => true, | |
255 | } | |
256 | } | |
257 | ||
258 | fn check_attrs(cx: &LateContext, span: Span, name: &Name, attrs: &[Attribute]) { | |
259 | if in_macro(span) { | |
260 | return; | |
261 | } | |
262 | ||
263 | for attr in attrs { | |
2c00a5a8 XL |
264 | if attr.is_sugared_doc { |
265 | return; | |
266 | } | |
267 | if attr.style == AttrStyle::Outer { | |
268 | if !is_present_in_source(cx, attr.span) { | |
269 | return; | |
270 | } | |
271 | ||
272 | let attr_to_item_span = Span::new(attr.span.lo(), span.lo(), span.ctxt()); | |
273 | ||
274 | if let Some(snippet) = snippet_opt(cx, attr_to_item_span) { | |
275 | let lines = snippet.split('\n').collect::<Vec<_>>(); | |
276 | if lines.iter().filter(|l| l.trim().is_empty()).count() > 1 { | |
277 | span_lint( | |
278 | cx, | |
279 | EMPTY_LINE_AFTER_OUTER_ATTR, | |
280 | attr_to_item_span, | |
281 | "Found an empty line after an outer attribute. Perhaps you forgot to add a '!' to make it an inner attribute?" | |
282 | ); | |
283 | ||
284 | } | |
285 | } | |
286 | } | |
287 | ||
ea8adc8c XL |
288 | if let Some(ref values) = attr.meta_item_list() { |
289 | if values.len() != 1 || attr.name().map_or(true, |n| n != "inline") { | |
290 | continue; | |
291 | } | |
292 | if is_word(&values[0], "always") { | |
293 | span_lint( | |
294 | cx, | |
295 | INLINE_ALWAYS, | |
296 | attr.span, | |
297 | &format!( | |
298 | "you have declared `#[inline(always)]` on `{}`. This is usually a bad idea", | |
299 | name | |
300 | ), | |
301 | ); | |
302 | } | |
303 | } | |
304 | } | |
305 | } | |
306 | ||
307 | fn check_semver(cx: &LateContext, span: Span, lit: &Lit) { | |
308 | if let LitKind::Str(ref is, _) = lit.node { | |
309 | if Version::parse(&is.as_str()).is_ok() { | |
310 | return; | |
311 | } | |
312 | } | |
313 | span_lint( | |
314 | cx, | |
315 | DEPRECATED_SEMVER, | |
316 | span, | |
317 | "the since field must contain a semver-compliant version", | |
318 | ); | |
319 | } | |
320 | ||
321 | fn is_word(nmi: &NestedMetaItem, expected: &str) -> bool { | |
322 | if let NestedMetaItemKind::MetaItem(ref mi) = nmi.node { | |
323 | mi.is_word() && mi.name() == expected | |
324 | } else { | |
325 | false | |
326 | } | |
327 | } | |
2c00a5a8 XL |
328 | |
329 | // If the snippet is empty, it's an attribute that was inserted during macro | |
330 | // expansion and we want to ignore those, because they could come from external | |
331 | // sources that the user has no control over. | |
332 | // For some reason these attributes don't have any expansion info on them, so | |
333 | // we have to check it this way until there is a better way. | |
334 | fn is_present_in_source(cx: &LateContext, span: Span) -> bool { | |
335 | if let Some(snippet) = snippet_opt(cx, span) { | |
336 | if snippet.is_empty() { | |
337 | return false; | |
338 | } | |
339 | } | |
340 | true | |
341 | } |