]>
Commit | Line | Data |
---|---|---|
041b39d2 XL |
1 | //! This module implements some validity checks for attributes. |
2 | //! In particular it verifies that `#[inline]` and `#[repr]` attributes are | |
3 | //! attached to items that actually support them and if there are | |
4 | //! conflicts between multiple such attributes attached to the same | |
5 | //! item. | |
6 | ||
ba9703b0 XL |
7 | use rustc_middle::hir::map::Map; |
8 | use rustc_middle::ty::query::Providers; | |
9 | use rustc_middle::ty::TyCtxt; | |
e1599b0c | 10 | |
74b04a01 XL |
11 | use rustc_ast::ast::{Attribute, NestedMetaItem}; |
12 | use rustc_ast::attr; | |
dfeec247 XL |
13 | use rustc_errors::struct_span_err; |
14 | use rustc_hir as hir; | |
15 | use rustc_hir::def_id::DefId; | |
16 | use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor}; | |
74b04a01 XL |
17 | use rustc_hir::{self, HirId, Item, ItemKind, TraitItem}; |
18 | use rustc_hir::{MethodKind, Target}; | |
dfeec247 | 19 | use rustc_session::lint::builtin::{CONFLICTING_REPR_HINTS, UNUSED_ATTRIBUTES}; |
74b04a01 | 20 | use rustc_session::parse::feature_err; |
dfeec247 XL |
21 | use rustc_span::symbol::sym; |
22 | use rustc_span::Span; | |
b039eaaf | 23 | |
74b04a01 XL |
24 | fn target_from_impl_item<'tcx>(tcx: TyCtxt<'tcx>, impl_item: &hir::ImplItem<'_>) -> Target { |
25 | match impl_item.kind { | |
26 | hir::ImplItemKind::Const(..) => Target::AssocConst, | |
ba9703b0 | 27 | hir::ImplItemKind::Fn(..) => { |
74b04a01 XL |
28 | let parent_hir_id = tcx.hir().get_parent_item(impl_item.hir_id); |
29 | let containing_item = tcx.hir().expect_item(parent_hir_id); | |
30 | let containing_impl_is_for_trait = match &containing_item.kind { | |
31 | hir::ItemKind::Impl { ref of_trait, .. } => of_trait.is_some(), | |
32 | _ => bug!("parent of an ImplItem must be an Impl"), | |
33 | }; | |
34 | if containing_impl_is_for_trait { | |
e74abb32 | 35 | Target::Method(MethodKind::Trait { body: true }) |
74b04a01 XL |
36 | } else { |
37 | Target::Method(MethodKind::Inherent) | |
e74abb32 | 38 | } |
b039eaaf | 39 | } |
74b04a01 | 40 | hir::ImplItemKind::TyAlias(..) | hir::ImplItemKind::OpaqueTy(..) => Target::AssocTy, |
b039eaaf SL |
41 | } |
42 | } | |
43 | ||
dc9dc135 XL |
44 | struct CheckAttrVisitor<'tcx> { |
45 | tcx: TyCtxt<'tcx>, | |
b039eaaf SL |
46 | } |
47 | ||
dc9dc135 | 48 | impl CheckAttrVisitor<'tcx> { |
9fa01778 | 49 | /// Checks any attribute. |
e74abb32 XL |
50 | fn check_attributes( |
51 | &self, | |
52 | hir_id: HirId, | |
dfeec247 | 53 | attrs: &'hir [Attribute], |
e74abb32 XL |
54 | span: &Span, |
55 | target: Target, | |
dfeec247 | 56 | item: Option<&Item<'_>>, |
e74abb32 XL |
57 | ) { |
58 | let mut is_valid = true; | |
59 | for attr in attrs { | |
60 | is_valid &= if attr.check_name(sym::inline) { | |
61 | self.check_inline(hir_id, attr, span, target) | |
48663c56 | 62 | } else if attr.check_name(sym::non_exhaustive) { |
e74abb32 | 63 | self.check_non_exhaustive(attr, span, target) |
48663c56 | 64 | } else if attr.check_name(sym::marker) { |
e74abb32 XL |
65 | self.check_marker(attr, span, target) |
66 | } else if attr.check_name(sym::target_feature) { | |
67 | self.check_target_feature(attr, span, target) | |
68 | } else if attr.check_name(sym::track_caller) { | |
69 | self.check_track_caller(&attr.span, attrs, span, target) | |
70 | } else { | |
71 | true | |
72 | }; | |
041b39d2 | 73 | } |
2c00a5a8 | 74 | |
e74abb32 XL |
75 | if !is_valid { |
76 | return; | |
77 | } | |
78 | ||
f9f354fc XL |
79 | if matches!(target, Target::Fn | Target::Method(_) | Target::ForeignFn) { |
80 | self.tcx.ensure().codegen_fn_attrs(self.tcx.hir().local_def_id(hir_id)); | |
e74abb32 XL |
81 | } |
82 | ||
dfeec247 | 83 | self.check_repr(attrs, span, target, item, hir_id); |
e74abb32 XL |
84 | self.check_used(attrs, target); |
85 | } | |
86 | ||
87 | /// Checks if an `#[inline]` is applied to a function or a closure. Returns `true` if valid. | |
88 | fn check_inline(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) -> bool { | |
89 | match target { | |
dfeec247 XL |
90 | Target::Fn |
91 | | Target::Closure | |
ba9703b0 | 92 | | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true, |
e74abb32 | 93 | Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => { |
74b04a01 XL |
94 | self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
95 | lint.build("`#[inline]` is ignored on function prototypes").emit() | |
96 | }); | |
e74abb32 XL |
97 | true |
98 | } | |
99 | // FIXME(#65833): We permit associated consts to have an `#[inline]` attribute with | |
100 | // just a lint, because we previously erroneously allowed it and some crates used it | |
101 | // accidentally, to to be compatible with crates depending on them, we can't throw an | |
102 | // error here. | |
103 | Target::AssocConst => { | |
74b04a01 XL |
104 | self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
105 | lint.build("`#[inline]` is ignored on constants") | |
106 | .warn( | |
107 | "this was previously accepted by the compiler but is \ | |
108 | being phased out; it will become a hard error in \ | |
109 | a future release!", | |
110 | ) | |
111 | .note( | |
112 | "see issue #65833 <https://github.com/rust-lang/rust/issues/65833> \ | |
113 | for more information", | |
114 | ) | |
115 | .emit(); | |
116 | }); | |
e74abb32 XL |
117 | true |
118 | } | |
119 | _ => { | |
120 | struct_span_err!( | |
121 | self.tcx.sess, | |
122 | attr.span, | |
123 | E0518, | |
124 | "attribute should be applied to function or closure", | |
dfeec247 XL |
125 | ) |
126 | .span_label(*span, "not a function or closure") | |
127 | .emit(); | |
e74abb32 XL |
128 | false |
129 | } | |
130 | } | |
041b39d2 XL |
131 | } |
132 | ||
e74abb32 XL |
133 | /// Checks if a `#[track_caller]` is applied to a non-naked function. Returns `true` if valid. |
134 | fn check_track_caller( | |
135 | &self, | |
136 | attr_span: &Span, | |
dfeec247 | 137 | attrs: &'hir [Attribute], |
e74abb32 XL |
138 | span: &Span, |
139 | target: Target, | |
140 | ) -> bool { | |
141 | match target { | |
ba9703b0 | 142 | _ if attr::contains_name(attrs, sym::naked) => { |
e74abb32 XL |
143 | struct_span_err!( |
144 | self.tcx.sess, | |
145 | *attr_span, | |
146 | E0736, | |
147 | "cannot use `#[track_caller]` with `#[naked]`", | |
dfeec247 XL |
148 | ) |
149 | .emit(); | |
e74abb32 XL |
150 | false |
151 | } | |
ba9703b0 | 152 | Target::Fn | Target::Method(..) | Target::ForeignFn => true, |
e74abb32 XL |
153 | _ => { |
154 | struct_span_err!( | |
155 | self.tcx.sess, | |
156 | *attr_span, | |
157 | E0739, | |
158 | "attribute should be applied to function" | |
159 | ) | |
160 | .span_label(*span, "not a function") | |
83c7162d | 161 | .emit(); |
e74abb32 XL |
162 | false |
163 | } | |
83c7162d XL |
164 | } |
165 | } | |
166 | ||
e74abb32 | 167 | /// Checks if the `#[non_exhaustive]` attribute on an `item` is valid. Returns `true` if valid. |
dfeec247 | 168 | fn check_non_exhaustive(&self, attr: &Attribute, span: &Span, target: Target) -> bool { |
83c7162d | 169 | match target { |
e74abb32 | 170 | Target::Struct | Target::Enum => true, |
83c7162d | 171 | _ => { |
dfeec247 XL |
172 | struct_span_err!( |
173 | self.tcx.sess, | |
174 | attr.span, | |
175 | E0701, | |
176 | "attribute can only be applied to a struct or enum" | |
177 | ) | |
178 | .span_label(*span, "not a struct or enum") | |
179 | .emit(); | |
e74abb32 | 180 | false |
83c7162d XL |
181 | } |
182 | } | |
b039eaaf SL |
183 | } |
184 | ||
e74abb32 XL |
185 | /// Checks if the `#[marker]` attribute on an `item` is valid. Returns `true` if valid. |
186 | fn check_marker(&self, attr: &Attribute, span: &Span, target: Target) -> bool { | |
0bf4aa26 | 187 | match target { |
e74abb32 | 188 | Target::Trait => true, |
0bf4aa26 | 189 | _ => { |
dfeec247 XL |
190 | self.tcx |
191 | .sess | |
0bf4aa26 | 192 | .struct_span_err(attr.span, "attribute can only be applied to a trait") |
e74abb32 | 193 | .span_label(*span, "not a trait") |
0bf4aa26 | 194 | .emit(); |
e74abb32 | 195 | false |
0bf4aa26 XL |
196 | } |
197 | } | |
0bf4aa26 XL |
198 | } |
199 | ||
e74abb32 XL |
200 | /// Checks if the `#[target_feature]` attribute on `item` is valid. Returns `true` if valid. |
201 | fn check_target_feature(&self, attr: &Attribute, span: &Span, target: Target) -> bool { | |
202 | match target { | |
dfeec247 | 203 | Target::Fn |
ba9703b0 | 204 | | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true, |
e74abb32 | 205 | _ => { |
dfeec247 XL |
206 | self.tcx |
207 | .sess | |
e74abb32 XL |
208 | .struct_span_err(attr.span, "attribute should be applied to a function") |
209 | .span_label(*span, "not a function") | |
210 | .emit(); | |
211 | false | |
dfeec247 | 212 | } |
e74abb32 XL |
213 | } |
214 | } | |
215 | ||
9fa01778 | 216 | /// Checks if the `#[repr]` attributes on `item` are valid. |
e74abb32 XL |
217 | fn check_repr( |
218 | &self, | |
dfeec247 | 219 | attrs: &'hir [Attribute], |
e74abb32 XL |
220 | span: &Span, |
221 | target: Target, | |
dfeec247 XL |
222 | item: Option<&Item<'_>>, |
223 | hir_id: HirId, | |
e74abb32 | 224 | ) { |
2c00a5a8 XL |
225 | // Extract the names of all repr hints, e.g., [foo, bar, align] for: |
226 | // ``` | |
227 | // #[repr(foo)] | |
228 | // #[repr(bar, align(8))] | |
229 | // ``` | |
e74abb32 | 230 | let hints: Vec<_> = attrs |
2c00a5a8 | 231 | .iter() |
48663c56 | 232 | .filter(|attr| attr.check_name(sym::repr)) |
2c00a5a8 | 233 | .filter_map(|attr| attr.meta_item_list()) |
b7449926 | 234 | .flatten() |
2c00a5a8 | 235 | .collect(); |
9e0c209e | 236 | |
ff7c6d11 XL |
237 | let mut int_reprs = 0; |
238 | let mut is_c = false; | |
239 | let mut is_simd = false; | |
2c00a5a8 XL |
240 | let mut is_transparent = false; |
241 | ||
242 | for hint in &hints { | |
48663c56 XL |
243 | let (article, allowed_targets) = match hint.name_or_empty() { |
244 | name @ sym::C | name @ sym::align => { | |
245 | is_c |= name == sym::C; | |
dc9dc135 XL |
246 | match target { |
247 | Target::Struct | Target::Union | Target::Enum => continue, | |
248 | _ => ("a", "struct, enum, or union"), | |
9e0c209e SL |
249 | } |
250 | } | |
48663c56 | 251 | sym::packed => { |
dfeec247 XL |
252 | if target != Target::Struct && target != Target::Union { |
253 | ("a", "struct or union") | |
92a42be0 | 254 | } else { |
dfeec247 | 255 | continue; |
b039eaaf SL |
256 | } |
257 | } | |
48663c56 | 258 | sym::simd => { |
ff7c6d11 | 259 | is_simd = true; |
dfeec247 | 260 | if target != Target::Struct { ("a", "struct") } else { continue } |
b039eaaf | 261 | } |
48663c56 | 262 | sym::transparent => { |
2c00a5a8 | 263 | is_transparent = true; |
dc9dc135 XL |
264 | match target { |
265 | Target::Struct | Target::Union | Target::Enum => continue, | |
266 | _ => ("a", "struct, enum, or union"), | |
cc61c64b XL |
267 | } |
268 | } | |
74b04a01 XL |
269 | sym::no_niche => { |
270 | if !self.tcx.features().enabled(sym::no_niche) { | |
271 | feature_err( | |
272 | &self.tcx.sess.parse_sess, | |
273 | sym::no_niche, | |
274 | hint.span(), | |
275 | "the attribute `repr(no_niche)` is currently unstable", | |
276 | ) | |
277 | .emit(); | |
278 | } | |
279 | match target { | |
280 | Target::Struct | Target::Enum => continue, | |
281 | _ => ("a", "struct or enum"), | |
282 | } | |
283 | } | |
dfeec247 XL |
284 | sym::i8 |
285 | | sym::u8 | |
286 | | sym::i16 | |
287 | | sym::u16 | |
288 | | sym::i32 | |
289 | | sym::u32 | |
290 | | sym::i64 | |
291 | | sym::u64 | |
292 | | sym::isize | |
293 | | sym::usize => { | |
ff7c6d11 | 294 | int_reprs += 1; |
dfeec247 | 295 | if target != Target::Enum { ("an", "enum") } else { continue } |
b039eaaf | 296 | } |
92a42be0 SL |
297 | _ => continue, |
298 | }; | |
0531ce1d | 299 | self.emit_repr_error( |
532ac7d7 | 300 | hint.span(), |
e74abb32 | 301 | *span, |
0531ce1d XL |
302 | &format!("attribute should be applied to {}", allowed_targets), |
303 | &format!("not {} {}", article, allowed_targets), | |
304 | ) | |
9e0c209e | 305 | } |
ff7c6d11 | 306 | |
2c00a5a8 XL |
307 | // Just point at all repr hints if there are any incompatibilities. |
308 | // This is not ideal, but tracking precisely which ones are at fault is a huge hassle. | |
532ac7d7 | 309 | let hint_spans = hints.iter().map(|hint| hint.span()); |
2c00a5a8 | 310 | |
74b04a01 XL |
311 | // Error on repr(transparent, <anything else apart from no_niche>). |
312 | let non_no_niche = |hint: &&NestedMetaItem| hint.name_or_empty() != sym::no_niche; | |
313 | let non_no_niche_count = hints.iter().filter(non_no_niche).count(); | |
314 | if is_transparent && non_no_niche_count > 1 { | |
2c00a5a8 | 315 | let hint_spans: Vec<_> = hint_spans.clone().collect(); |
dfeec247 XL |
316 | struct_span_err!( |
317 | self.tcx.sess, | |
318 | hint_spans, | |
319 | E0692, | |
320 | "transparent {} cannot have other repr hints", | |
321 | target | |
322 | ) | |
323 | .emit(); | |
2c00a5a8 | 324 | } |
ff7c6d11 XL |
325 | // Warn on repr(u8, u16), repr(C, simd), and c-like-enum-repr(C, u8) |
326 | if (int_reprs > 1) | |
dfeec247 XL |
327 | || (is_simd && is_c) |
328 | || (int_reprs == 1 && is_c && item.map_or(false, |item| is_c_like_enum(item))) | |
329 | { | |
74b04a01 XL |
330 | self.tcx.struct_span_lint_hir( |
331 | CONFLICTING_REPR_HINTS, | |
332 | hir_id, | |
333 | hint_spans.collect::<Vec<Span>>(), | |
334 | |lint| { | |
335 | lint.build("conflicting representation hints") | |
336 | .code(rustc_errors::error_code!(E0566)) | |
337 | .emit(); | |
338 | }, | |
339 | ); | |
b039eaaf SL |
340 | } |
341 | } | |
0531ce1d XL |
342 | |
343 | fn emit_repr_error( | |
344 | &self, | |
345 | hint_span: Span, | |
346 | label_span: Span, | |
347 | hint_message: &str, | |
348 | label_message: &str, | |
349 | ) { | |
350 | struct_span_err!(self.tcx.sess, hint_span, E0517, "{}", hint_message) | |
351 | .span_label(label_span, label_message) | |
352 | .emit(); | |
353 | } | |
354 | ||
dfeec247 | 355 | fn check_stmt_attributes(&self, stmt: &hir::Stmt<'_>) { |
0531ce1d | 356 | // When checking statements ignore expressions, they will be checked later |
e74abb32 | 357 | if let hir::StmtKind::Local(ref l) = stmt.kind { |
9fa01778 | 358 | for attr in l.attrs.iter() { |
48663c56 | 359 | if attr.check_name(sym::inline) { |
ba9703b0 | 360 | self.check_inline(l.hir_id, attr, &stmt.span, Target::Statement); |
0531ce1d | 361 | } |
48663c56 | 362 | if attr.check_name(sym::repr) { |
0531ce1d XL |
363 | self.emit_repr_error( |
364 | attr.span, | |
365 | stmt.span, | |
8faf50e0 | 366 | "attribute should not be applied to a statement", |
dc9dc135 | 367 | "not a struct, enum, or union", |
0531ce1d XL |
368 | ); |
369 | } | |
370 | } | |
371 | } | |
372 | } | |
373 | ||
dfeec247 | 374 | fn check_expr_attributes(&self, expr: &hir::Expr<'_>) { |
e74abb32 | 375 | let target = match expr.kind { |
8faf50e0 | 376 | hir::ExprKind::Closure(..) => Target::Closure, |
83c7162d XL |
377 | _ => Target::Expression, |
378 | }; | |
0531ce1d | 379 | for attr in expr.attrs.iter() { |
48663c56 | 380 | if attr.check_name(sym::inline) { |
ba9703b0 | 381 | self.check_inline(expr.hir_id, attr, &expr.span, target); |
0531ce1d | 382 | } |
48663c56 | 383 | if attr.check_name(sym::repr) { |
0531ce1d XL |
384 | self.emit_repr_error( |
385 | attr.span, | |
386 | expr.span, | |
8faf50e0 | 387 | "attribute should not be applied to an expression", |
dc9dc135 | 388 | "not defining a struct, enum, or union", |
0531ce1d XL |
389 | ); |
390 | } | |
391 | } | |
f9f354fc XL |
392 | if target == Target::Closure { |
393 | self.tcx.ensure().codegen_fn_attrs(self.tcx.hir().local_def_id(expr.hir_id)); | |
394 | } | |
0531ce1d | 395 | } |
83c7162d | 396 | |
dfeec247 | 397 | fn check_used(&self, attrs: &'hir [Attribute], target: Target) { |
e74abb32 | 398 | for attr in attrs { |
48663c56 | 399 | if attr.check_name(sym::used) && target != Target::Static { |
dfeec247 XL |
400 | self.tcx |
401 | .sess | |
83c7162d XL |
402 | .span_err(attr.span, "attribute must be applied to a `static` variable"); |
403 | } | |
404 | } | |
405 | } | |
b039eaaf SL |
406 | } |
407 | ||
dc9dc135 | 408 | impl Visitor<'tcx> for CheckAttrVisitor<'tcx> { |
dfeec247 XL |
409 | type Map = Map<'tcx>; |
410 | ||
ba9703b0 XL |
411 | fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { |
412 | NestedVisitorMap::OnlyBodies(self.tcx.hir()) | |
2c00a5a8 XL |
413 | } |
414 | ||
dfeec247 | 415 | fn visit_item(&mut self, item: &'tcx Item<'tcx>) { |
b039eaaf | 416 | let target = Target::from_item(item); |
dfeec247 | 417 | self.check_attributes(item.hir_id, item.attrs, &item.span, target, Some(item)); |
0531ce1d XL |
418 | intravisit::walk_item(self, item) |
419 | } | |
420 | ||
dfeec247 | 421 | fn visit_trait_item(&mut self, trait_item: &'tcx TraitItem<'tcx>) { |
e74abb32 XL |
422 | let target = Target::from_trait_item(trait_item); |
423 | self.check_attributes(trait_item.hir_id, &trait_item.attrs, &trait_item.span, target, None); | |
424 | intravisit::walk_trait_item(self, trait_item) | |
425 | } | |
426 | ||
dfeec247 | 427 | fn visit_foreign_item(&mut self, f_item: &'tcx hir::ForeignItem<'tcx>) { |
e74abb32 XL |
428 | let target = Target::from_foreign_item(f_item); |
429 | self.check_attributes(f_item.hir_id, &f_item.attrs, &f_item.span, target, None); | |
430 | intravisit::walk_foreign_item(self, f_item) | |
431 | } | |
432 | ||
dfeec247 | 433 | fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) { |
74b04a01 | 434 | let target = target_from_impl_item(self.tcx, impl_item); |
e74abb32 XL |
435 | self.check_attributes(impl_item.hir_id, &impl_item.attrs, &impl_item.span, target, None); |
436 | intravisit::walk_impl_item(self, impl_item) | |
437 | } | |
0531ce1d | 438 | |
dfeec247 | 439 | fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) { |
0531ce1d XL |
440 | self.check_stmt_attributes(stmt); |
441 | intravisit::walk_stmt(self, stmt) | |
442 | } | |
443 | ||
dfeec247 | 444 | fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) { |
0531ce1d XL |
445 | self.check_expr_attributes(expr); |
446 | intravisit::walk_expr(self, expr) | |
b039eaaf SL |
447 | } |
448 | } | |
449 | ||
dfeec247 | 450 | fn is_c_like_enum(item: &Item<'_>) -> bool { |
e74abb32 | 451 | if let ItemKind::Enum(ref def, _) = item.kind { |
dfeec247 | 452 | for variant in def.variants { |
e1599b0c | 453 | match variant.data { |
9fa01778 | 454 | hir::VariantData::Unit(..) => { /* continue */ } |
e74abb32 | 455 | _ => return false, |
ff7c6d11 XL |
456 | } |
457 | } | |
458 | true | |
459 | } else { | |
460 | false | |
461 | } | |
462 | } | |
0731742a | 463 | |
416331ca | 464 | fn check_mod_attrs(tcx: TyCtxt<'_>, module_def_id: DefId) { |
dfeec247 XL |
465 | tcx.hir() |
466 | .visit_item_likes_in_module(module_def_id, &mut CheckAttrVisitor { tcx }.as_deep_visitor()); | |
0731742a XL |
467 | } |
468 | ||
469 | pub(crate) fn provide(providers: &mut Providers<'_>) { | |
dfeec247 | 470 | *providers = Providers { check_mod_attrs, ..*providers }; |
0731742a | 471 | } |