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Commit | Line | Data |
---|---|---|
dfeec247 | 1 | use crate::{LateContext, LateLintPass, LintContext}; |
3dfed10e | 2 | use rustc_ast as ast; |
74b04a01 | 3 | use rustc_attr as attr; |
dfeec247 XL |
4 | use rustc_data_structures::fx::FxHashSet; |
5 | use rustc_errors::Applicability; | |
6 | use rustc_hir as hir; | |
94222f64 XL |
7 | use rustc_hir::def_id::DefId; |
8 | use rustc_hir::{is_range_literal, Expr, ExprKind, Node}; | |
c295e0f8 | 9 | use rustc_middle::ty::layout::{IntegerExt, LayoutOf, SizeSkeleton}; |
ba9703b0 | 10 | use rustc_middle::ty::subst::SubstsRef; |
923072b8 | 11 | use rustc_middle::ty::{self, AdtKind, DefIdTree, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable}; |
dfeec247 XL |
12 | use rustc_span::source_map; |
13 | use rustc_span::symbol::sym; | |
94222f64 | 14 | use rustc_span::{Span, Symbol, DUMMY_SP}; |
04454e1e | 15 | use rustc_target::abi::{Abi, WrappingRange}; |
c295e0f8 | 16 | use rustc_target::abi::{Integer, TagEncoding, Variants}; |
3dfed10e | 17 | use rustc_target::spec::abi::Abi as SpecAbi; |
9fa01778 | 18 | |
dfeec247 | 19 | use std::cmp; |
cdc7bbd5 | 20 | use std::iter; |
29967ef6 | 21 | use std::ops::ControlFlow; |
3dfed10e | 22 | use tracing::debug; |
9fa01778 | 23 | |
b039eaaf | 24 | declare_lint! { |
1b1a35ee XL |
25 | /// The `unused_comparisons` lint detects comparisons made useless by |
26 | /// limits of the types involved. | |
27 | /// | |
28 | /// ### Example | |
29 | /// | |
30 | /// ```rust | |
31 | /// fn foo(x: u8) { | |
32 | /// x >= 0; | |
33 | /// } | |
34 | /// ``` | |
35 | /// | |
36 | /// {{produces}} | |
37 | /// | |
38 | /// ### Explanation | |
39 | /// | |
40 | /// A useless comparison may indicate a mistake, and should be fixed or | |
41 | /// removed. | |
b039eaaf SL |
42 | UNUSED_COMPARISONS, |
43 | Warn, | |
44 | "comparisons made useless by limits of the types involved" | |
45 | } | |
46 | ||
47 | declare_lint! { | |
1b1a35ee XL |
48 | /// The `overflowing_literals` lint detects literal out of range for its |
49 | /// type. | |
50 | /// | |
51 | /// ### Example | |
52 | /// | |
53 | /// ```rust,compile_fail | |
54 | /// let x: u8 = 1000; | |
55 | /// ``` | |
56 | /// | |
57 | /// {{produces}} | |
58 | /// | |
59 | /// ### Explanation | |
60 | /// | |
61 | /// It is usually a mistake to use a literal that overflows the type where | |
62 | /// it is used. Either use a literal that is within range, or change the | |
63 | /// type to be within the range of the literal. | |
b039eaaf | 64 | OVERFLOWING_LITERALS, |
9fa01778 XL |
65 | Deny, |
66 | "literal out of range for its type" | |
b039eaaf SL |
67 | } |
68 | ||
5bcae85e | 69 | declare_lint! { |
1b1a35ee XL |
70 | /// The `variant_size_differences` lint detects enums with widely varying |
71 | /// variant sizes. | |
72 | /// | |
73 | /// ### Example | |
74 | /// | |
75 | /// ```rust,compile_fail | |
76 | /// #![deny(variant_size_differences)] | |
77 | /// enum En { | |
78 | /// V0(u8), | |
79 | /// VBig([u8; 1024]), | |
80 | /// } | |
81 | /// ``` | |
82 | /// | |
83 | /// {{produces}} | |
84 | /// | |
85 | /// ### Explanation | |
86 | /// | |
87 | /// It can be a mistake to add a variant to an enum that is much larger | |
88 | /// than the other variants, bloating the overall size required for all | |
89 | /// variants. This can impact performance and memory usage. This is | |
90 | /// triggered if one variant is more than 3 times larger than the | |
91 | /// second-largest variant. | |
92 | /// | |
93 | /// Consider placing the large variant's contents on the heap (for example | |
94 | /// via [`Box`]) to keep the overall size of the enum itself down. | |
95 | /// | |
96 | /// This lint is "allow" by default because it can be noisy, and may not be | |
97 | /// an actual problem. Decisions about this should be guided with | |
98 | /// profiling and benchmarking. | |
99 | /// | |
100 | /// [`Box`]: https://doc.rust-lang.org/std/boxed/index.html | |
5bcae85e SL |
101 | VARIANT_SIZE_DIFFERENCES, |
102 | Allow, | |
103 | "detects enums with widely varying variant sizes" | |
104 | } | |
105 | ||
b039eaaf SL |
106 | #[derive(Copy, Clone)] |
107 | pub struct TypeLimits { | |
108 | /// Id of the last visited negated expression | |
ba9703b0 | 109 | negated_expr_id: Option<hir::HirId>, |
b039eaaf SL |
110 | } |
111 | ||
532ac7d7 XL |
112 | impl_lint_pass!(TypeLimits => [UNUSED_COMPARISONS, OVERFLOWING_LITERALS]); |
113 | ||
b039eaaf SL |
114 | impl TypeLimits { |
115 | pub fn new() -> TypeLimits { | |
ba9703b0 | 116 | TypeLimits { negated_expr_id: None } |
b039eaaf SL |
117 | } |
118 | } | |
119 | ||
48663c56 XL |
120 | /// Attempts to special-case the overflowing literal lint when it occurs as a range endpoint. |
121 | /// Returns `true` iff the lint was overridden. | |
f035d41b XL |
122 | fn lint_overflowing_range_endpoint<'tcx>( |
123 | cx: &LateContext<'tcx>, | |
48663c56 XL |
124 | lit: &hir::Lit, |
125 | lit_val: u128, | |
126 | max: u128, | |
dfeec247 XL |
127 | expr: &'tcx hir::Expr<'tcx>, |
128 | parent_expr: &'tcx hir::Expr<'tcx>, | |
60c5eb7d | 129 | ty: &str, |
48663c56 XL |
130 | ) -> bool { |
131 | // We only want to handle exclusive (`..`) ranges, | |
132 | // which are represented as `ExprKind::Struct`. | |
74b04a01 | 133 | let mut overwritten = false; |
e74abb32 | 134 | if let ExprKind::Struct(_, eps, _) = &parent_expr.kind { |
416331ca XL |
135 | if eps.len() != 2 { |
136 | return false; | |
137 | } | |
48663c56 XL |
138 | // We can suggest using an inclusive range |
139 | // (`..=`) instead only if it is the `end` that is | |
140 | // overflowing and only by 1. | |
141 | if eps[1].expr.hir_id == expr.hir_id && lit_val - 1 == max { | |
74b04a01 XL |
142 | cx.struct_span_lint(OVERFLOWING_LITERALS, parent_expr.span, |lint| { |
143 | let mut err = lint.build(&format!("range endpoint is out of range for `{}`", ty)); | |
144 | if let Ok(start) = cx.sess().source_map().span_to_snippet(eps[0].span) { | |
145 | use ast::{LitIntType, LitKind}; | |
146 | // We need to preserve the literal's suffix, | |
147 | // as it may determine typing information. | |
148 | let suffix = match lit.node { | |
29967ef6 XL |
149 | LitKind::Int(_, LitIntType::Signed(s)) => s.name_str(), |
150 | LitKind::Int(_, LitIntType::Unsigned(s)) => s.name_str(), | |
151 | LitKind::Int(_, LitIntType::Unsuffixed) => "", | |
74b04a01 XL |
152 | _ => bug!(), |
153 | }; | |
154 | let suggestion = format!("{}..={}{}", start, lit_val - 1, suffix); | |
155 | err.span_suggestion( | |
156 | parent_expr.span, | |
04454e1e | 157 | "use an inclusive range instead", |
74b04a01 XL |
158 | suggestion, |
159 | Applicability::MachineApplicable, | |
160 | ); | |
161 | err.emit(); | |
162 | overwritten = true; | |
163 | } | |
164 | }); | |
48663c56 XL |
165 | } |
166 | } | |
74b04a01 | 167 | overwritten |
48663c56 XL |
168 | } |
169 | ||
170 | // For `isize` & `usize`, be conservative with the warnings, so that the | |
171 | // warnings are consistent between 32- and 64-bit platforms. | |
5869c6ff | 172 | fn int_ty_range(int_ty: ty::IntTy) -> (i128, i128) { |
48663c56 | 173 | match int_ty { |
5869c6ff XL |
174 | ty::IntTy::Isize => (i64::MIN.into(), i64::MAX.into()), |
175 | ty::IntTy::I8 => (i8::MIN.into(), i8::MAX.into()), | |
176 | ty::IntTy::I16 => (i16::MIN.into(), i16::MAX.into()), | |
177 | ty::IntTy::I32 => (i32::MIN.into(), i32::MAX.into()), | |
178 | ty::IntTy::I64 => (i64::MIN.into(), i64::MAX.into()), | |
179 | ty::IntTy::I128 => (i128::MIN, i128::MAX), | |
48663c56 XL |
180 | } |
181 | } | |
182 | ||
5869c6ff | 183 | fn uint_ty_range(uint_ty: ty::UintTy) -> (u128, u128) { |
29967ef6 | 184 | let max = match uint_ty { |
5869c6ff XL |
185 | ty::UintTy::Usize => u64::MAX.into(), |
186 | ty::UintTy::U8 => u8::MAX.into(), | |
187 | ty::UintTy::U16 => u16::MAX.into(), | |
188 | ty::UintTy::U32 => u32::MAX.into(), | |
189 | ty::UintTy::U64 => u64::MAX.into(), | |
190 | ty::UintTy::U128 => u128::MAX, | |
29967ef6 XL |
191 | }; |
192 | (0, max) | |
48663c56 XL |
193 | } |
194 | ||
f035d41b | 195 | fn get_bin_hex_repr(cx: &LateContext<'_>, lit: &hir::Lit) -> Option<String> { |
48663c56 XL |
196 | let src = cx.sess().source_map().span_to_snippet(lit.span).ok()?; |
197 | let firstch = src.chars().next()?; | |
198 | ||
199 | if firstch == '0' { | |
200 | match src.chars().nth(1) { | |
ba9703b0 | 201 | Some('x' | 'b') => return Some(src), |
48663c56 XL |
202 | _ => return None, |
203 | } | |
204 | } | |
205 | ||
206 | None | |
207 | } | |
208 | ||
209 | fn report_bin_hex_error( | |
f035d41b | 210 | cx: &LateContext<'_>, |
dfeec247 | 211 | expr: &hir::Expr<'_>, |
48663c56 XL |
212 | ty: attr::IntType, |
213 | repr_str: String, | |
214 | val: u128, | |
215 | negative: bool, | |
216 | ) { | |
ba9703b0 | 217 | let size = Integer::from_attr(&cx.tcx, ty).size(); |
74b04a01 XL |
218 | cx.struct_span_lint(OVERFLOWING_LITERALS, expr.span, |lint| { |
219 | let (t, actually) = match ty { | |
220 | attr::IntType::SignedInt(t) => { | |
6a06907d XL |
221 | let actually = if negative { |
222 | -(size.sign_extend(val) as i128) | |
223 | } else { | |
224 | size.sign_extend(val) as i128 | |
225 | }; | |
74b04a01 XL |
226 | (t.name_str(), actually.to_string()) |
227 | } | |
228 | attr::IntType::UnsignedInt(t) => { | |
29967ef6 | 229 | let actually = size.truncate(val); |
74b04a01 XL |
230 | (t.name_str(), actually.to_string()) |
231 | } | |
232 | }; | |
6a06907d XL |
233 | let mut err = lint.build(&format!("literal out of range for `{}`", t)); |
234 | if negative { | |
235 | // If the value is negative, | |
236 | // emits a note about the value itself, apart from the literal. | |
237 | err.note(&format!( | |
238 | "the literal `{}` (decimal `{}`) does not fit into \ | |
239 | the type `{}`", | |
240 | repr_str, val, t | |
241 | )); | |
242 | err.note(&format!("and the value `-{}` will become `{}{}`", repr_str, actually, t)); | |
243 | } else { | |
244 | err.note(&format!( | |
245 | "the literal `{}` (decimal `{}`) does not fit into \ | |
246 | the type `{}` and will become `{}{}`", | |
247 | repr_str, val, t, actually, t | |
248 | )); | |
249 | } | |
f035d41b | 250 | if let Some(sugg_ty) = |
5099ac24 | 251 | get_type_suggestion(cx.typeck_results().node_type(expr.hir_id), val, negative) |
74b04a01 XL |
252 | { |
253 | if let Some(pos) = repr_str.chars().position(|c| c == 'i' || c == 'u') { | |
254 | let (sans_suffix, _) = repr_str.split_at(pos); | |
255 | err.span_suggestion( | |
256 | expr.span, | |
6a06907d | 257 | &format!("consider using the type `{}` instead", sugg_ty), |
74b04a01 XL |
258 | format!("{}{}", sans_suffix, sugg_ty), |
259 | Applicability::MachineApplicable, | |
260 | ); | |
261 | } else { | |
6a06907d | 262 | err.help(&format!("consider using the type `{}` instead", sugg_ty)); |
74b04a01 | 263 | } |
48663c56 | 264 | } |
74b04a01 XL |
265 | err.emit(); |
266 | }); | |
48663c56 XL |
267 | } |
268 | ||
269 | // This function finds the next fitting type and generates a suggestion string. | |
270 | // It searches for fitting types in the following way (`X < Y`): | |
271 | // - `iX`: if literal fits in `uX` => `uX`, else => `iY` | |
272 | // - `-iX` => `iY` | |
273 | // - `uX` => `uY` | |
274 | // | |
275 | // No suggestion for: `isize`, `usize`. | |
60c5eb7d | 276 | fn get_type_suggestion(t: Ty<'_>, val: u128, negative: bool) -> Option<&'static str> { |
5869c6ff XL |
277 | use ty::IntTy::*; |
278 | use ty::UintTy::*; | |
48663c56 XL |
279 | macro_rules! find_fit { |
280 | ($ty:expr, $val:expr, $negative:expr, | |
281 | $($type:ident => [$($utypes:expr),*] => [$($itypes:expr),*]),+) => { | |
282 | { | |
283 | let _neg = if negative { 1 } else { 0 }; | |
284 | match $ty { | |
285 | $($type => { | |
286 | $(if !negative && val <= uint_ty_range($utypes).1 { | |
60c5eb7d | 287 | return Some($utypes.name_str()) |
48663c56 XL |
288 | })* |
289 | $(if val <= int_ty_range($itypes).1 as u128 + _neg { | |
60c5eb7d | 290 | return Some($itypes.name_str()) |
48663c56 XL |
291 | })* |
292 | None | |
dc9dc135 | 293 | },)+ |
48663c56 XL |
294 | _ => None |
295 | } | |
296 | } | |
297 | } | |
298 | } | |
1b1a35ee | 299 | match t.kind() { |
48663c56 XL |
300 | ty::Int(i) => find_fit!(i, val, negative, |
301 | I8 => [U8] => [I16, I32, I64, I128], | |
302 | I16 => [U16] => [I32, I64, I128], | |
303 | I32 => [U32] => [I64, I128], | |
304 | I64 => [U64] => [I128], | |
305 | I128 => [U128] => []), | |
306 | ty::Uint(u) => find_fit!(u, val, negative, | |
307 | U8 => [U8, U16, U32, U64, U128] => [], | |
308 | U16 => [U16, U32, U64, U128] => [], | |
309 | U32 => [U32, U64, U128] => [], | |
310 | U64 => [U64, U128] => [], | |
311 | U128 => [U128] => []), | |
312 | _ => None, | |
313 | } | |
314 | } | |
315 | ||
f035d41b XL |
316 | fn lint_int_literal<'tcx>( |
317 | cx: &LateContext<'tcx>, | |
48663c56 | 318 | type_limits: &TypeLimits, |
dfeec247 | 319 | e: &'tcx hir::Expr<'tcx>, |
48663c56 | 320 | lit: &hir::Lit, |
5869c6ff | 321 | t: ty::IntTy, |
48663c56 XL |
322 | v: u128, |
323 | ) { | |
29967ef6 | 324 | let int_type = t.normalize(cx.sess().target.pointer_width); |
ba9703b0 | 325 | let (min, max) = int_ty_range(int_type); |
48663c56 | 326 | let max = max as u128; |
ba9703b0 | 327 | let negative = type_limits.negated_expr_id == Some(e.hir_id); |
48663c56 XL |
328 | |
329 | // Detect literal value out of range [min, max] inclusive | |
330 | // avoiding use of -min to prevent overflow/panic | |
331 | if (negative && v > max + 1) || (!negative && v > max) { | |
332 | if let Some(repr_str) = get_bin_hex_repr(cx, lit) { | |
5869c6ff XL |
333 | report_bin_hex_error( |
334 | cx, | |
335 | e, | |
336 | attr::IntType::SignedInt(ty::ast_int_ty(t)), | |
337 | repr_str, | |
338 | v, | |
339 | negative, | |
340 | ); | |
48663c56 XL |
341 | return; |
342 | } | |
343 | ||
dc9dc135 XL |
344 | let par_id = cx.tcx.hir().get_parent_node(e.hir_id); |
345 | if let Node::Expr(par_e) = cx.tcx.hir().get(par_id) { | |
e74abb32 | 346 | if let hir::ExprKind::Struct(..) = par_e.kind { |
3dfed10e | 347 | if is_range_literal(par_e) |
60c5eb7d | 348 | && lint_overflowing_range_endpoint(cx, lit, v, max, e, par_e, t.name_str()) |
48663c56 XL |
349 | { |
350 | // The overflowing literal lint was overridden. | |
351 | return; | |
352 | } | |
353 | } | |
354 | } | |
355 | ||
74b04a01 | 356 | cx.struct_span_lint(OVERFLOWING_LITERALS, e.span, |lint| { |
6a06907d XL |
357 | let mut err = lint.build(&format!("literal out of range for `{}`", t.name_str())); |
358 | err.note(&format!( | |
359 | "the literal `{}` does not fit into the type `{}` whose range is `{}..={}`", | |
360 | cx.sess() | |
361 | .source_map() | |
362 | .span_to_snippet(lit.span) | |
363 | .expect("must get snippet from literal"), | |
364 | t.name_str(), | |
365 | min, | |
366 | max, | |
367 | )); | |
368 | if let Some(sugg_ty) = | |
5099ac24 | 369 | get_type_suggestion(cx.typeck_results().node_type(e.hir_id), v, negative) |
6a06907d XL |
370 | { |
371 | err.help(&format!("consider using the type `{}` instead", sugg_ty)); | |
372 | } | |
373 | err.emit(); | |
74b04a01 | 374 | }); |
48663c56 XL |
375 | } |
376 | } | |
377 | ||
f035d41b XL |
378 | fn lint_uint_literal<'tcx>( |
379 | cx: &LateContext<'tcx>, | |
dfeec247 | 380 | e: &'tcx hir::Expr<'tcx>, |
48663c56 | 381 | lit: &hir::Lit, |
5869c6ff | 382 | t: ty::UintTy, |
48663c56 | 383 | ) { |
29967ef6 | 384 | let uint_type = t.normalize(cx.sess().target.pointer_width); |
48663c56 XL |
385 | let (min, max) = uint_ty_range(uint_type); |
386 | let lit_val: u128 = match lit.node { | |
387 | // _v is u8, within range by definition | |
388 | ast::LitKind::Byte(_v) => return, | |
389 | ast::LitKind::Int(v, _) => v, | |
390 | _ => bug!(), | |
391 | }; | |
392 | if lit_val < min || lit_val > max { | |
dc9dc135 XL |
393 | let parent_id = cx.tcx.hir().get_parent_node(e.hir_id); |
394 | if let Node::Expr(par_e) = cx.tcx.hir().get(parent_id) { | |
e74abb32 | 395 | match par_e.kind { |
48663c56 | 396 | hir::ExprKind::Cast(..) => { |
1b1a35ee | 397 | if let ty::Char = cx.typeck_results().expr_ty(par_e).kind() { |
74b04a01 XL |
398 | cx.struct_span_lint(OVERFLOWING_LITERALS, par_e.span, |lint| { |
399 | lint.build("only `u8` can be cast into `char`") | |
400 | .span_suggestion( | |
401 | par_e.span, | |
04454e1e | 402 | "use a `char` literal instead", |
74b04a01 XL |
403 | format!("'\\u{{{:X}}}'", lit_val), |
404 | Applicability::MachineApplicable, | |
405 | ) | |
406 | .emit(); | |
407 | }); | |
48663c56 XL |
408 | return; |
409 | } | |
410 | } | |
3dfed10e | 411 | hir::ExprKind::Struct(..) if is_range_literal(par_e) => { |
dfeec247 XL |
412 | let t = t.name_str(); |
413 | if lint_overflowing_range_endpoint(cx, lit, lit_val, max, e, par_e, t) { | |
414 | // The overflowing literal lint was overridden. | |
415 | return; | |
48663c56 | 416 | } |
dfeec247 | 417 | } |
48663c56 XL |
418 | _ => {} |
419 | } | |
420 | } | |
421 | if let Some(repr_str) = get_bin_hex_repr(cx, lit) { | |
5869c6ff XL |
422 | report_bin_hex_error( |
423 | cx, | |
424 | e, | |
425 | attr::IntType::UnsignedInt(ty::ast_uint_ty(t)), | |
426 | repr_str, | |
427 | lit_val, | |
428 | false, | |
429 | ); | |
48663c56 XL |
430 | return; |
431 | } | |
74b04a01 | 432 | cx.struct_span_lint(OVERFLOWING_LITERALS, e.span, |lint| { |
ba9703b0 XL |
433 | lint.build(&format!("literal out of range for `{}`", t.name_str())) |
434 | .note(&format!( | |
435 | "the literal `{}` does not fit into the type `{}` whose range is `{}..={}`", | |
436 | cx.sess() | |
437 | .source_map() | |
438 | .span_to_snippet(lit.span) | |
439 | .expect("must get snippet from literal"), | |
440 | t.name_str(), | |
441 | min, | |
442 | max, | |
443 | )) | |
5e7ed085 | 444 | .emit(); |
74b04a01 | 445 | }); |
48663c56 XL |
446 | } |
447 | } | |
448 | ||
f035d41b XL |
449 | fn lint_literal<'tcx>( |
450 | cx: &LateContext<'tcx>, | |
48663c56 | 451 | type_limits: &TypeLimits, |
dfeec247 | 452 | e: &'tcx hir::Expr<'tcx>, |
48663c56 XL |
453 | lit: &hir::Lit, |
454 | ) { | |
1b1a35ee | 455 | match *cx.typeck_results().node_type(e.hir_id).kind() { |
48663c56 XL |
456 | ty::Int(t) => { |
457 | match lit.node { | |
ba9703b0 | 458 | ast::LitKind::Int(v, ast::LitIntType::Signed(_) | ast::LitIntType::Unsuffixed) => { |
48663c56 XL |
459 | lint_int_literal(cx, type_limits, e, lit, t, v) |
460 | } | |
461 | _ => bug!(), | |
462 | }; | |
463 | } | |
dfeec247 | 464 | ty::Uint(t) => lint_uint_literal(cx, e, lit, t), |
48663c56 XL |
465 | ty::Float(t) => { |
466 | let is_infinite = match lit.node { | |
dfeec247 | 467 | ast::LitKind::Float(v, _) => match t { |
5869c6ff XL |
468 | ty::FloatTy::F32 => v.as_str().parse().map(f32::is_infinite), |
469 | ty::FloatTy::F64 => v.as_str().parse().map(f64::is_infinite), | |
dfeec247 | 470 | }, |
48663c56 XL |
471 | _ => bug!(), |
472 | }; | |
473 | if is_infinite == Ok(true) { | |
74b04a01 | 474 | cx.struct_span_lint(OVERFLOWING_LITERALS, e.span, |lint| { |
ba9703b0 XL |
475 | lint.build(&format!("literal out of range for `{}`", t.name_str())) |
476 | .note(&format!( | |
29967ef6 | 477 | "the literal `{}` does not fit into the type `{}` and will be converted to `{}::INFINITY`", |
ba9703b0 XL |
478 | cx.sess() |
479 | .source_map() | |
480 | .span_to_snippet(lit.span) | |
481 | .expect("must get snippet from literal"), | |
482 | t.name_str(), | |
483 | t.name_str(), | |
484 | )) | |
485 | .emit(); | |
74b04a01 | 486 | }); |
48663c56 XL |
487 | } |
488 | } | |
489 | _ => {} | |
490 | } | |
491 | } | |
492 | ||
f035d41b XL |
493 | impl<'tcx> LateLintPass<'tcx> for TypeLimits { |
494 | fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx hir::Expr<'tcx>) { | |
e74abb32 | 495 | match e.kind { |
6a06907d | 496 | hir::ExprKind::Unary(hir::UnOp::Neg, ref expr) => { |
b039eaaf | 497 | // propagate negation, if the negation itself isn't negated |
ba9703b0 XL |
498 | if self.negated_expr_id != Some(e.hir_id) { |
499 | self.negated_expr_id = Some(expr.hir_id); | |
b039eaaf | 500 | } |
c30ab7b3 | 501 | } |
8faf50e0 | 502 | hir::ExprKind::Binary(binop, ref l, ref r) => { |
32a655c1 | 503 | if is_comparison(binop) && !check_limits(cx, binop, &l, &r) { |
74b04a01 | 504 | cx.struct_span_lint(UNUSED_COMPARISONS, e.span, |lint| { |
5e7ed085 | 505 | lint.build("comparison is useless due to type limits").emit(); |
74b04a01 | 506 | }); |
b039eaaf | 507 | } |
c30ab7b3 | 508 | } |
48663c56 XL |
509 | hir::ExprKind::Lit(ref lit) => lint_literal(cx, self, e, lit), |
510 | _ => {} | |
b039eaaf SL |
511 | }; |
512 | ||
c30ab7b3 | 513 | fn is_valid<T: cmp::PartialOrd>(binop: hir::BinOp, v: T, min: T, max: T) -> bool { |
b039eaaf | 514 | match binop.node { |
8faf50e0 XL |
515 | hir::BinOpKind::Lt => v > min && v <= max, |
516 | hir::BinOpKind::Le => v >= min && v < max, | |
517 | hir::BinOpKind::Gt => v >= min && v < max, | |
518 | hir::BinOpKind::Ge => v > min && v <= max, | |
519 | hir::BinOpKind::Eq | hir::BinOpKind::Ne => v >= min && v <= max, | |
c30ab7b3 | 520 | _ => bug!(), |
b039eaaf SL |
521 | } |
522 | } | |
523 | ||
524 | fn rev_binop(binop: hir::BinOp) -> hir::BinOp { | |
dfeec247 XL |
525 | source_map::respan( |
526 | binop.span, | |
527 | match binop.node { | |
528 | hir::BinOpKind::Lt => hir::BinOpKind::Gt, | |
529 | hir::BinOpKind::Le => hir::BinOpKind::Ge, | |
530 | hir::BinOpKind::Gt => hir::BinOpKind::Lt, | |
531 | hir::BinOpKind::Ge => hir::BinOpKind::Le, | |
532 | _ => return binop, | |
533 | }, | |
534 | ) | |
b039eaaf SL |
535 | } |
536 | ||
dfeec247 | 537 | fn check_limits( |
f035d41b | 538 | cx: &LateContext<'_>, |
dfeec247 XL |
539 | binop: hir::BinOp, |
540 | l: &hir::Expr<'_>, | |
541 | r: &hir::Expr<'_>, | |
542 | ) -> bool { | |
e74abb32 | 543 | let (lit, expr, swap) = match (&l.kind, &r.kind) { |
8faf50e0 XL |
544 | (&hir::ExprKind::Lit(_), _) => (l, r, true), |
545 | (_, &hir::ExprKind::Lit(_)) => (r, l, false), | |
c30ab7b3 | 546 | _ => return true, |
b039eaaf SL |
547 | }; |
548 | // Normalize the binop so that the literal is always on the RHS in | |
549 | // the comparison | |
c30ab7b3 | 550 | let norm_binop = if swap { rev_binop(binop) } else { binop }; |
1b1a35ee | 551 | match *cx.typeck_results().node_type(expr.hir_id).kind() { |
b7449926 | 552 | ty::Int(int_ty) => { |
b039eaaf | 553 | let (min, max) = int_ty_range(int_ty); |
e74abb32 | 554 | let lit_val: i128 = match lit.kind { |
dfeec247 | 555 | hir::ExprKind::Lit(ref li) => match li.node { |
ba9703b0 XL |
556 | ast::LitKind::Int( |
557 | v, | |
558 | ast::LitIntType::Signed(_) | ast::LitIntType::Unsuffixed, | |
559 | ) => v as i128, | |
dfeec247 | 560 | _ => return true, |
32a655c1 | 561 | }, |
dfeec247 | 562 | _ => bug!(), |
b039eaaf SL |
563 | }; |
564 | is_valid(norm_binop, lit_val, min, max) | |
565 | } | |
b7449926 | 566 | ty::Uint(uint_ty) => { |
dfeec247 | 567 | let (min, max): (u128, u128) = uint_ty_range(uint_ty); |
e74abb32 | 568 | let lit_val: u128 = match lit.kind { |
dfeec247 XL |
569 | hir::ExprKind::Lit(ref li) => match li.node { |
570 | ast::LitKind::Int(v, _) => v, | |
571 | _ => return true, | |
32a655c1 | 572 | }, |
dfeec247 | 573 | _ => bug!(), |
b039eaaf SL |
574 | }; |
575 | is_valid(norm_binop, lit_val, min, max) | |
576 | } | |
c30ab7b3 | 577 | _ => true, |
b039eaaf SL |
578 | } |
579 | } | |
580 | ||
581 | fn is_comparison(binop: hir::BinOp) -> bool { | |
29967ef6 XL |
582 | matches!( |
583 | binop.node, | |
dfeec247 | 584 | hir::BinOpKind::Eq |
29967ef6 XL |
585 | | hir::BinOpKind::Lt |
586 | | hir::BinOpKind::Le | |
587 | | hir::BinOpKind::Ne | |
588 | | hir::BinOpKind::Ge | |
589 | | hir::BinOpKind::Gt | |
590 | ) | |
b039eaaf | 591 | } |
b039eaaf SL |
592 | } |
593 | } | |
594 | ||
595 | declare_lint! { | |
1b1a35ee XL |
596 | /// The `improper_ctypes` lint detects incorrect use of types in foreign |
597 | /// modules. | |
598 | /// | |
599 | /// ### Example | |
600 | /// | |
601 | /// ```rust | |
602 | /// extern "C" { | |
603 | /// static STATIC: String; | |
604 | /// } | |
605 | /// ``` | |
606 | /// | |
607 | /// {{produces}} | |
608 | /// | |
609 | /// ### Explanation | |
610 | /// | |
611 | /// The compiler has several checks to verify that types used in `extern` | |
612 | /// blocks are safe and follow certain rules to ensure proper | |
613 | /// compatibility with the foreign interfaces. This lint is issued when it | |
614 | /// detects a probable mistake in a definition. The lint usually should | |
615 | /// provide a description of the issue, along with possibly a hint on how | |
616 | /// to resolve it. | |
b039eaaf SL |
617 | IMPROPER_CTYPES, |
618 | Warn, | |
619 | "proper use of libc types in foreign modules" | |
620 | } | |
621 | ||
f035d41b XL |
622 | declare_lint_pass!(ImproperCTypesDeclarations => [IMPROPER_CTYPES]); |
623 | ||
624 | declare_lint! { | |
1b1a35ee XL |
625 | /// The `improper_ctypes_definitions` lint detects incorrect use of |
626 | /// [`extern` function] definitions. | |
627 | /// | |
628 | /// [`extern` function]: https://doc.rust-lang.org/reference/items/functions.html#extern-function-qualifier | |
629 | /// | |
630 | /// ### Example | |
631 | /// | |
632 | /// ```rust | |
633 | /// # #![allow(unused)] | |
634 | /// pub extern "C" fn str_type(p: &str) { } | |
635 | /// ``` | |
636 | /// | |
637 | /// {{produces}} | |
638 | /// | |
639 | /// ### Explanation | |
640 | /// | |
641 | /// There are many parameter and return types that may be specified in an | |
642 | /// `extern` function that are not compatible with the given ABI. This | |
643 | /// lint is an alert that these types should not be used. The lint usually | |
644 | /// should provide a description of the issue, along with possibly a hint | |
645 | /// on how to resolve it. | |
f035d41b XL |
646 | IMPROPER_CTYPES_DEFINITIONS, |
647 | Warn, | |
648 | "proper use of libc types in foreign item definitions" | |
649 | } | |
650 | ||
651 | declare_lint_pass!(ImproperCTypesDefinitions => [IMPROPER_CTYPES_DEFINITIONS]); | |
652 | ||
3dfed10e | 653 | #[derive(Clone, Copy)] |
923072b8 | 654 | pub(crate) enum CItemKind { |
3dfed10e XL |
655 | Declaration, |
656 | Definition, | |
f035d41b | 657 | } |
532ac7d7 | 658 | |
dc9dc135 | 659 | struct ImproperCTypesVisitor<'a, 'tcx> { |
f035d41b | 660 | cx: &'a LateContext<'tcx>, |
3dfed10e | 661 | mode: CItemKind, |
b039eaaf SL |
662 | } |
663 | ||
0531ce1d | 664 | enum FfiResult<'tcx> { |
b039eaaf | 665 | FfiSafe, |
0531ce1d | 666 | FfiPhantom(Ty<'tcx>), |
f035d41b | 667 | FfiUnsafe { ty: Ty<'tcx>, reason: String, help: Option<String> }, |
b039eaaf SL |
668 | } |
669 | ||
923072b8 FG |
670 | pub(crate) fn nonnull_optimization_guaranteed<'tcx>( |
671 | tcx: TyCtxt<'tcx>, | |
672 | def: ty::AdtDef<'tcx>, | |
673 | ) -> bool { | |
04454e1e | 674 | tcx.has_attr(def.did(), sym::rustc_nonnull_optimization_guaranteed) |
1b1a35ee XL |
675 | } |
676 | ||
677 | /// `repr(transparent)` structs can have a single non-ZST field, this function returns that | |
678 | /// field. | |
679 | pub fn transparent_newtype_field<'a, 'tcx>( | |
680 | tcx: TyCtxt<'tcx>, | |
681 | variant: &'a ty::VariantDef, | |
682 | ) -> Option<&'a ty::FieldDef> { | |
683 | let param_env = tcx.param_env(variant.def_id); | |
17df50a5 | 684 | variant.fields.iter().find(|field| { |
1b1a35ee | 685 | let field_ty = tcx.type_of(field.did); |
5869c6ff | 686 | let is_zst = tcx.layout_of(param_env.and(field_ty)).map_or(false, |layout| layout.is_zst()); |
17df50a5 XL |
687 | !is_zst |
688 | }) | |
1b1a35ee XL |
689 | } |
690 | ||
3dfed10e | 691 | /// Is type known to be non-null? |
6a06907d | 692 | fn ty_is_known_nonnull<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, mode: CItemKind) -> bool { |
3dfed10e | 693 | let tcx = cx.tcx; |
1b1a35ee | 694 | match ty.kind() { |
3dfed10e XL |
695 | ty::FnPtr(_) => true, |
696 | ty::Ref(..) => true, | |
697 | ty::Adt(def, _) if def.is_box() && matches!(mode, CItemKind::Definition) => true, | |
5e7ed085 FG |
698 | ty::Adt(def, substs) if def.repr().transparent() && !def.is_union() => { |
699 | let marked_non_null = nonnull_optimization_guaranteed(tcx, *def); | |
3dfed10e | 700 | |
1b1a35ee | 701 | if marked_non_null { |
3dfed10e | 702 | return true; |
f9652781 | 703 | } |
1b1a35ee | 704 | |
6a06907d XL |
705 | // Types with a `#[repr(no_niche)]` attribute have their niche hidden. |
706 | // The attribute is used by the UnsafeCell for example (the only use so far). | |
5e7ed085 | 707 | if def.repr().hide_niche() { |
6a06907d XL |
708 | return false; |
709 | } | |
710 | ||
5e7ed085 | 711 | def.variants() |
17df50a5 XL |
712 | .iter() |
713 | .filter_map(|variant| transparent_newtype_field(cx.tcx, variant)) | |
714 | .any(|field| ty_is_known_nonnull(cx, field.ty(tcx, substs), mode)) | |
b039eaaf | 715 | } |
3dfed10e | 716 | _ => false, |
b039eaaf | 717 | } |
3dfed10e | 718 | } |
dc9dc135 | 719 | |
3dfed10e XL |
720 | /// Given a non-null scalar (or transparent) type `ty`, return the nullable version of that type. |
721 | /// If the type passed in was not scalar, returns None. | |
722 | fn get_nullable_type<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'tcx>> { | |
723 | let tcx = cx.tcx; | |
1b1a35ee | 724 | Some(match *ty.kind() { |
3dfed10e XL |
725 | ty::Adt(field_def, field_substs) => { |
726 | let inner_field_ty = { | |
5e7ed085 FG |
727 | let first_non_zst_ty = field_def |
728 | .variants() | |
729 | .iter() | |
730 | .filter_map(|v| transparent_newtype_field(cx.tcx, v)); | |
3dfed10e XL |
731 | debug_assert_eq!( |
732 | first_non_zst_ty.clone().count(), | |
733 | 1, | |
734 | "Wrong number of fields for transparent type" | |
735 | ); | |
736 | first_non_zst_ty | |
737 | .last() | |
738 | .expect("No non-zst fields in transparent type.") | |
739 | .ty(tcx, field_substs) | |
740 | }; | |
741 | return get_nullable_type(cx, inner_field_ty); | |
742 | } | |
743 | ty::Int(ty) => tcx.mk_mach_int(ty), | |
744 | ty::Uint(ty) => tcx.mk_mach_uint(ty), | |
745 | ty::RawPtr(ty_mut) => tcx.mk_ptr(ty_mut), | |
746 | // As these types are always non-null, the nullable equivalent of | |
747 | // Option<T> of these types are their raw pointer counterparts. | |
748 | ty::Ref(_region, ty, mutbl) => tcx.mk_ptr(ty::TypeAndMut { ty, mutbl }), | |
749 | ty::FnPtr(..) => { | |
750 | // There is no nullable equivalent for Rust's function pointers -- you | |
751 | // must use an Option<fn(..) -> _> to represent it. | |
752 | ty | |
753 | } | |
754 | ||
755 | // We should only ever reach this case if ty_is_known_nonnull is extended | |
756 | // to other types. | |
757 | ref unhandled => { | |
758 | debug!( | |
759 | "get_nullable_type: Unhandled scalar kind: {:?} while checking {:?}", | |
760 | unhandled, ty | |
761 | ); | |
762 | return None; | |
763 | } | |
764 | }) | |
765 | } | |
766 | ||
767 | /// Check if this enum can be safely exported based on the "nullable pointer optimization". If it | |
1b1a35ee | 768 | /// can, return the type that `ty` can be safely converted to, otherwise return `None`. |
3dfed10e XL |
769 | /// Currently restricted to function pointers, boxes, references, `core::num::NonZero*`, |
770 | /// `core::ptr::NonNull`, and `#[repr(transparent)]` newtypes. | |
771 | /// FIXME: This duplicates code in codegen. | |
923072b8 | 772 | pub(crate) fn repr_nullable_ptr<'tcx>( |
3dfed10e XL |
773 | cx: &LateContext<'tcx>, |
774 | ty: Ty<'tcx>, | |
775 | ckind: CItemKind, | |
776 | ) -> Option<Ty<'tcx>> { | |
777 | debug!("is_repr_nullable_ptr(cx, ty = {:?})", ty); | |
1b1a35ee | 778 | if let ty::Adt(ty_def, substs) = ty.kind() { |
5e7ed085 | 779 | let field_ty = match &ty_def.variants().raw[..] { |
17df50a5 XL |
780 | [var_one, var_two] => match (&var_one.fields[..], &var_two.fields[..]) { |
781 | ([], [field]) | ([field], []) => field.ty(cx.tcx, substs), | |
782 | _ => return None, | |
783 | }, | |
784 | _ => return None, | |
f035d41b | 785 | }; |
dc9dc135 | 786 | |
3dfed10e XL |
787 | if !ty_is_known_nonnull(cx, field_ty, ckind) { |
788 | return None; | |
f035d41b | 789 | } |
dc9dc135 | 790 | |
3dfed10e XL |
791 | // At this point, the field's type is known to be nonnull and the parent enum is Option-like. |
792 | // If the computed size for the field and the enum are different, the nonnull optimization isn't | |
793 | // being applied (and we've got a problem somewhere). | |
794 | let compute_size_skeleton = |t| SizeSkeleton::compute(t, cx.tcx, cx.param_env).unwrap(); | |
f035d41b XL |
795 | if !compute_size_skeleton(ty).same_size(compute_size_skeleton(field_ty)) { |
796 | bug!("improper_ctypes: Option nonnull optimization not applied?"); | |
797 | } | |
dc9dc135 | 798 | |
3dfed10e XL |
799 | // Return the nullable type this Option-like enum can be safely represented with. |
800 | let field_ty_abi = &cx.layout_of(field_ty).unwrap().abi; | |
801 | if let Abi::Scalar(field_ty_scalar) = field_ty_abi { | |
04454e1e FG |
802 | match field_ty_scalar.valid_range(cx) { |
803 | WrappingRange { start: 0, end } | |
804 | if end == field_ty_scalar.size(&cx.tcx).unsigned_int_max() - 1 => | |
805 | { | |
5e7ed085 FG |
806 | return Some(get_nullable_type(cx, field_ty).unwrap()); |
807 | } | |
04454e1e | 808 | WrappingRange { start: 1, .. } => { |
3dfed10e XL |
809 | return Some(get_nullable_type(cx, field_ty).unwrap()); |
810 | } | |
04454e1e FG |
811 | WrappingRange { start, end } => { |
812 | unreachable!("Unhandled start and end range: ({}, {})", start, end) | |
813 | } | |
3dfed10e XL |
814 | }; |
815 | } | |
f035d41b | 816 | } |
3dfed10e XL |
817 | None |
818 | } | |
b039eaaf | 819 | |
3dfed10e | 820 | impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> { |
60c5eb7d XL |
821 | /// Check if the type is array and emit an unsafe type lint. |
822 | fn check_for_array_ty(&mut self, sp: Span, ty: Ty<'tcx>) -> bool { | |
1b1a35ee | 823 | if let ty::Array(..) = ty.kind() { |
60c5eb7d XL |
824 | self.emit_ffi_unsafe_type_lint( |
825 | ty, | |
826 | sp, | |
827 | "passing raw arrays by value is not FFI-safe", | |
828 | Some("consider passing a pointer to the array"), | |
829 | ); | |
830 | true | |
831 | } else { | |
832 | false | |
833 | } | |
834 | } | |
835 | ||
f035d41b XL |
836 | /// Checks if the given field's type is "ffi-safe". |
837 | fn check_field_type_for_ffi( | |
838 | &self, | |
839 | cache: &mut FxHashSet<Ty<'tcx>>, | |
840 | field: &ty::FieldDef, | |
841 | substs: SubstsRef<'tcx>, | |
842 | ) -> FfiResult<'tcx> { | |
843 | let field_ty = field.ty(self.cx.tcx, substs); | |
844 | if field_ty.has_opaque_types() { | |
845 | self.check_type_for_ffi(cache, field_ty) | |
846 | } else { | |
847 | let field_ty = self.cx.tcx.normalize_erasing_regions(self.cx.param_env, field_ty); | |
848 | self.check_type_for_ffi(cache, field_ty) | |
849 | } | |
850 | } | |
851 | ||
852 | /// Checks if the given `VariantDef`'s field types are "ffi-safe". | |
853 | fn check_variant_for_ffi( | |
854 | &self, | |
855 | cache: &mut FxHashSet<Ty<'tcx>>, | |
856 | ty: Ty<'tcx>, | |
5e7ed085 | 857 | def: ty::AdtDef<'tcx>, |
f035d41b XL |
858 | variant: &ty::VariantDef, |
859 | substs: SubstsRef<'tcx>, | |
860 | ) -> FfiResult<'tcx> { | |
861 | use FfiResult::*; | |
862 | ||
5e7ed085 | 863 | if def.repr().transparent() { |
c295e0f8 | 864 | // Can assume that at most one field is not a ZST, so only check |
f035d41b | 865 | // that field's type for FFI-safety. |
1b1a35ee | 866 | if let Some(field) = transparent_newtype_field(self.cx.tcx, variant) { |
f035d41b XL |
867 | self.check_field_type_for_ffi(cache, field, substs) |
868 | } else { | |
c295e0f8 XL |
869 | // All fields are ZSTs; this means that the type should behave |
870 | // like (), which is FFI-unsafe | |
871 | FfiUnsafe { | |
872 | ty, | |
873 | reason: "this struct contains only zero-sized fields".into(), | |
874 | help: None, | |
875 | } | |
f035d41b XL |
876 | } |
877 | } else { | |
878 | // We can't completely trust repr(C) markings; make sure the fields are | |
879 | // actually safe. | |
880 | let mut all_phantom = !variant.fields.is_empty(); | |
881 | for field in &variant.fields { | |
882 | match self.check_field_type_for_ffi(cache, &field, substs) { | |
883 | FfiSafe => { | |
884 | all_phantom = false; | |
885 | } | |
886 | FfiPhantom(..) if def.is_enum() => { | |
887 | return FfiUnsafe { | |
888 | ty, | |
889 | reason: "this enum contains a PhantomData field".into(), | |
890 | help: None, | |
891 | }; | |
892 | } | |
893 | FfiPhantom(..) => {} | |
894 | r => return r, | |
895 | } | |
896 | } | |
897 | ||
898 | if all_phantom { FfiPhantom(ty) } else { FfiSafe } | |
899 | } | |
900 | } | |
901 | ||
9fa01778 | 902 | /// Checks if the given type is "ffi-safe" (has a stable, well-defined |
b039eaaf | 903 | /// representation which can be exported to C code). |
dfeec247 | 904 | fn check_type_for_ffi(&self, cache: &mut FxHashSet<Ty<'tcx>>, ty: Ty<'tcx>) -> FfiResult<'tcx> { |
9fa01778 | 905 | use FfiResult::*; |
8bb4bdeb | 906 | |
3dfed10e | 907 | let tcx = self.cx.tcx; |
b039eaaf SL |
908 | |
909 | // Protect against infinite recursion, for example | |
910 | // `struct S(*mut S);`. | |
911 | // FIXME: A recursion limit is necessary as well, for irregular | |
b7449926 | 912 | // recursive types. |
b039eaaf SL |
913 | if !cache.insert(ty) { |
914 | return FfiSafe; | |
915 | } | |
916 | ||
fc512014 | 917 | match *ty.kind() { |
b7449926 | 918 | ty::Adt(def, substs) => { |
17df50a5 XL |
919 | if def.is_box() && matches!(self.mode, CItemKind::Definition) { |
920 | if ty.boxed_ty().is_sized(tcx.at(DUMMY_SP), self.cx.param_env) { | |
921 | return FfiSafe; | |
922 | } else { | |
923 | return FfiUnsafe { | |
924 | ty, | |
94222f64 | 925 | reason: "box cannot be represented as a single pointer".to_string(), |
17df50a5 XL |
926 | help: None, |
927 | }; | |
928 | } | |
929 | } | |
8bb4bdeb | 930 | if def.is_phantom_data() { |
0531ce1d | 931 | return FfiPhantom(ty); |
8bb4bdeb | 932 | } |
c30ab7b3 | 933 | match def.adt_kind() { |
f035d41b XL |
934 | AdtKind::Struct | AdtKind::Union => { |
935 | let kind = if def.is_struct() { "struct" } else { "union" }; | |
936 | ||
5e7ed085 | 937 | if !def.repr().c() && !def.repr().transparent() { |
0531ce1d | 938 | return FfiUnsafe { |
e1599b0c | 939 | ty, |
f035d41b XL |
940 | reason: format!("this {} has unspecified layout", kind), |
941 | help: Some(format!( | |
dfeec247 | 942 | "consider adding a `#[repr(C)]` or \ |
f035d41b XL |
943 | `#[repr(transparent)]` attribute to this {}", |
944 | kind | |
945 | )), | |
0531ce1d | 946 | }; |
c30ab7b3 | 947 | } |
b039eaaf | 948 | |
e74abb32 XL |
949 | let is_non_exhaustive = |
950 | def.non_enum_variant().is_field_list_non_exhaustive(); | |
5e7ed085 | 951 | if is_non_exhaustive && !def.did().is_local() { |
e74abb32 XL |
952 | return FfiUnsafe { |
953 | ty, | |
f035d41b | 954 | reason: format!("this {} is non-exhaustive", kind), |
e74abb32 XL |
955 | help: None, |
956 | }; | |
957 | } | |
958 | ||
2c00a5a8 | 959 | if def.non_enum_variant().fields.is_empty() { |
0531ce1d | 960 | return FfiUnsafe { |
e1599b0c | 961 | ty, |
f035d41b XL |
962 | reason: format!("this {} has no fields", kind), |
963 | help: Some(format!("consider adding a member to this {}", kind)), | |
0531ce1d | 964 | }; |
8bb4bdeb XL |
965 | } |
966 | ||
f035d41b | 967 | self.check_variant_for_ffi(cache, ty, def, def.non_enum_variant(), substs) |
b039eaaf | 968 | } |
c30ab7b3 | 969 | AdtKind::Enum => { |
5e7ed085 | 970 | if def.variants().is_empty() { |
c30ab7b3 SL |
971 | // Empty enums are okay... although sort of useless. |
972 | return FfiSafe; | |
973 | } | |
9e0c209e | 974 | |
c30ab7b3 SL |
975 | // Check for a repr() attribute to specify the size of the |
976 | // discriminant. | |
5e7ed085 FG |
977 | if !def.repr().c() && !def.repr().transparent() && def.repr().int.is_none() |
978 | { | |
8bb4bdeb | 979 | // Special-case types like `Option<extern fn()>`. |
3dfed10e | 980 | if repr_nullable_ptr(self.cx, ty, self.mode).is_none() { |
0531ce1d | 981 | return FfiUnsafe { |
e1599b0c | 982 | ty, |
f035d41b | 983 | reason: "enum has no representation hint".into(), |
dfeec247 XL |
984 | help: Some( |
985 | "consider adding a `#[repr(C)]`, \ | |
dc9dc135 | 986 | `#[repr(transparent)]`, or integer `#[repr(...)]` \ |
f035d41b XL |
987 | attribute to this enum" |
988 | .into(), | |
dfeec247 | 989 | ), |
0531ce1d | 990 | }; |
9e0c209e | 991 | } |
8bb4bdeb | 992 | } |
c30ab7b3 | 993 | |
5e7ed085 | 994 | if def.is_variant_list_non_exhaustive() && !def.did().is_local() { |
e74abb32 XL |
995 | return FfiUnsafe { |
996 | ty, | |
f035d41b | 997 | reason: "this enum is non-exhaustive".into(), |
e74abb32 XL |
998 | help: None, |
999 | }; | |
1000 | } | |
1001 | ||
c30ab7b3 | 1002 | // Check the contained variants. |
5e7ed085 | 1003 | for variant in def.variants() { |
e74abb32 XL |
1004 | let is_non_exhaustive = variant.is_field_list_non_exhaustive(); |
1005 | if is_non_exhaustive && !variant.def_id.is_local() { | |
1006 | return FfiUnsafe { | |
1007 | ty, | |
f035d41b | 1008 | reason: "this enum has non-exhaustive variants".into(), |
e74abb32 XL |
1009 | help: None, |
1010 | }; | |
1011 | } | |
1012 | ||
f035d41b XL |
1013 | match self.check_variant_for_ffi(cache, ty, def, variant, substs) { |
1014 | FfiSafe => (), | |
1015 | r => return r, | |
9e0c209e | 1016 | } |
b039eaaf | 1017 | } |
f035d41b | 1018 | |
c30ab7b3 | 1019 | FfiSafe |
b039eaaf SL |
1020 | } |
1021 | } | |
c30ab7b3 | 1022 | } |
b039eaaf | 1023 | |
b7449926 | 1024 | ty::Char => FfiUnsafe { |
e1599b0c | 1025 | ty, |
f035d41b XL |
1026 | reason: "the `char` type has no C equivalent".into(), |
1027 | help: Some("consider using `u32` or `libc::wchar_t` instead".into()), | |
0531ce1d | 1028 | }, |
b039eaaf | 1029 | |
5869c6ff | 1030 | ty::Int(ty::IntTy::I128) | ty::Uint(ty::UintTy::U128) => FfiUnsafe { |
e1599b0c | 1031 | ty, |
f035d41b | 1032 | reason: "128-bit integers don't currently have a known stable ABI".into(), |
0531ce1d XL |
1033 | help: None, |
1034 | }, | |
ea8adc8c | 1035 | |
b039eaaf | 1036 | // Primitive types with a stable representation. |
b7449926 | 1037 | ty::Bool | ty::Int(..) | ty::Uint(..) | ty::Float(..) | ty::Never => FfiSafe, |
b039eaaf | 1038 | |
b7449926 | 1039 | ty::Slice(_) => FfiUnsafe { |
e1599b0c | 1040 | ty, |
f035d41b XL |
1041 | reason: "slices have no C equivalent".into(), |
1042 | help: Some("consider using a raw pointer instead".into()), | |
0531ce1d XL |
1043 | }, |
1044 | ||
dfeec247 | 1045 | ty::Dynamic(..) => { |
f035d41b | 1046 | FfiUnsafe { ty, reason: "trait objects have no C equivalent".into(), help: None } |
dfeec247 | 1047 | } |
0531ce1d | 1048 | |
b7449926 | 1049 | ty::Str => FfiUnsafe { |
e1599b0c | 1050 | ty, |
f035d41b XL |
1051 | reason: "string slices have no C equivalent".into(), |
1052 | help: Some("consider using `*const u8` and a length instead".into()), | |
0531ce1d XL |
1053 | }, |
1054 | ||
b7449926 | 1055 | ty::Tuple(..) => FfiUnsafe { |
e1599b0c | 1056 | ty, |
f035d41b XL |
1057 | reason: "tuples have unspecified layout".into(), |
1058 | help: Some("consider using a struct instead".into()), | |
0531ce1d | 1059 | }, |
b039eaaf | 1060 | |
f035d41b XL |
1061 | ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) |
1062 | if { | |
3dfed10e | 1063 | matches!(self.mode, CItemKind::Definition) |
f035d41b XL |
1064 | && ty.is_sized(self.cx.tcx.at(DUMMY_SP), self.cx.param_env) |
1065 | } => | |
1066 | { | |
1067 | FfiSafe | |
1068 | } | |
1069 | ||
c295e0f8 XL |
1070 | ty::RawPtr(ty::TypeAndMut { ty, .. }) |
1071 | if match ty.kind() { | |
1072 | ty::Tuple(tuple) => tuple.is_empty(), | |
1073 | _ => false, | |
1074 | } => | |
1075 | { | |
1076 | FfiSafe | |
1077 | } | |
1078 | ||
dfeec247 XL |
1079 | ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) => { |
1080 | self.check_type_for_ffi(cache, ty) | |
1081 | } | |
b039eaaf | 1082 | |
60c5eb7d | 1083 | ty::Array(inner_ty, _) => self.check_type_for_ffi(cache, inner_ty), |
b039eaaf | 1084 | |
b7449926 | 1085 | ty::FnPtr(sig) => { |
f035d41b XL |
1086 | if self.is_internal_abi(sig.abi()) { |
1087 | return FfiUnsafe { | |
1088 | ty, | |
1089 | reason: "this function pointer has Rust-specific calling convention".into(), | |
1090 | help: Some( | |
1091 | "consider using an `extern fn(...) -> ...` \ | |
1092 | function pointer instead" | |
1093 | .into(), | |
1094 | ), | |
1095 | }; | |
b039eaaf SL |
1096 | } |
1097 | ||
fc512014 | 1098 | let sig = tcx.erase_late_bound_regions(sig); |
b7449926 | 1099 | if !sig.output().is_unit() { |
476ff2be | 1100 | let r = self.check_type_for_ffi(cache, sig.output()); |
5bcae85e SL |
1101 | match r { |
1102 | FfiSafe => {} | |
c30ab7b3 SL |
1103 | _ => { |
1104 | return r; | |
1105 | } | |
b039eaaf SL |
1106 | } |
1107 | } | |
476ff2be | 1108 | for arg in sig.inputs() { |
5099ac24 | 1109 | let r = self.check_type_for_ffi(cache, *arg); |
b039eaaf SL |
1110 | match r { |
1111 | FfiSafe => {} | |
c30ab7b3 SL |
1112 | _ => { |
1113 | return r; | |
1114 | } | |
b039eaaf SL |
1115 | } |
1116 | } | |
1117 | FfiSafe | |
1118 | } | |
1119 | ||
b7449926 XL |
1120 | ty::Foreign(..) => FfiSafe, |
1121 | ||
f035d41b XL |
1122 | // While opaque types are checked for earlier, if a projection in a struct field |
1123 | // normalizes to an opaque type, then it will reach this branch. | |
1124 | ty::Opaque(..) => { | |
1125 | FfiUnsafe { ty, reason: "opaque types have no C equivalent".into(), help: None } | |
1126 | } | |
1127 | ||
1128 | // `extern "C" fn` functions can have type parameters, which may or may not be FFI-safe, | |
1129 | // so they are currently ignored for the purposes of this lint. | |
3dfed10e | 1130 | ty::Param(..) | ty::Projection(..) if matches!(self.mode, CItemKind::Definition) => { |
f035d41b XL |
1131 | FfiSafe |
1132 | } | |
1133 | ||
dfeec247 | 1134 | ty::Param(..) |
f035d41b | 1135 | | ty::Projection(..) |
dfeec247 XL |
1136 | | ty::Infer(..) |
1137 | | ty::Bound(..) | |
f035d41b | 1138 | | ty::Error(_) |
dfeec247 XL |
1139 | | ty::Closure(..) |
1140 | | ty::Generator(..) | |
1141 | | ty::GeneratorWitness(..) | |
1142 | | ty::Placeholder(..) | |
dfeec247 | 1143 | | ty::FnDef(..) => bug!("unexpected type in foreign function: {:?}", ty), |
e1599b0c XL |
1144 | } |
1145 | } | |
1146 | ||
1147 | fn emit_ffi_unsafe_type_lint( | |
1148 | &mut self, | |
1149 | ty: Ty<'tcx>, | |
1150 | sp: Span, | |
1151 | note: &str, | |
1152 | help: Option<&str>, | |
1153 | ) { | |
f035d41b | 1154 | let lint = match self.mode { |
3dfed10e XL |
1155 | CItemKind::Declaration => IMPROPER_CTYPES, |
1156 | CItemKind::Definition => IMPROPER_CTYPES_DEFINITIONS, | |
f035d41b XL |
1157 | }; |
1158 | ||
1159 | self.cx.struct_span_lint(lint, sp, |lint| { | |
1160 | let item_description = match self.mode { | |
3dfed10e XL |
1161 | CItemKind::Declaration => "block", |
1162 | CItemKind::Definition => "fn", | |
f035d41b XL |
1163 | }; |
1164 | let mut diag = lint.build(&format!( | |
1165 | "`extern` {} uses type `{}`, which is not FFI-safe", | |
1166 | item_description, ty | |
1167 | )); | |
74b04a01 XL |
1168 | diag.span_label(sp, "not FFI-safe"); |
1169 | if let Some(help) = help { | |
1170 | diag.help(help); | |
e1599b0c | 1171 | } |
74b04a01 | 1172 | diag.note(note); |
1b1a35ee | 1173 | if let ty::Adt(def, _) = ty.kind() { |
5e7ed085 | 1174 | if let Some(sp) = self.cx.tcx.hir().span_if_local(def.did()) { |
74b04a01 XL |
1175 | diag.span_note(sp, "the type is defined here"); |
1176 | } | |
1177 | } | |
1178 | diag.emit(); | |
1179 | }); | |
e1599b0c XL |
1180 | } |
1181 | ||
1182 | fn check_for_opaque_ty(&mut self, sp: Span, ty: Ty<'tcx>) -> bool { | |
f035d41b XL |
1183 | struct ProhibitOpaqueTypes<'a, 'tcx> { |
1184 | cx: &'a LateContext<'tcx>, | |
fc512014 | 1185 | } |
e1599b0c | 1186 | |
f035d41b | 1187 | impl<'a, 'tcx> ty::fold::TypeVisitor<'tcx> for ProhibitOpaqueTypes<'a, 'tcx> { |
fc512014 XL |
1188 | type BreakTy = Ty<'tcx>; |
1189 | ||
1190 | fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> { | |
1b1a35ee | 1191 | match ty.kind() { |
fc512014 | 1192 | ty::Opaque(..) => ControlFlow::Break(ty), |
f035d41b XL |
1193 | // Consider opaque types within projections FFI-safe if they do not normalize |
1194 | // to more opaque types. | |
1195 | ty::Projection(..) => { | |
1196 | let ty = self.cx.tcx.normalize_erasing_regions(self.cx.param_env, ty); | |
1197 | ||
94222f64 | 1198 | // If `ty` is an opaque type directly then `super_visit_with` won't invoke |
f035d41b | 1199 | // this function again. |
29967ef6 XL |
1200 | if ty.has_opaque_types() { |
1201 | self.visit_ty(ty) | |
1202 | } else { | |
1203 | ControlFlow::CONTINUE | |
1204 | } | |
f035d41b XL |
1205 | } |
1206 | _ => ty.super_visit_with(self), | |
e1599b0c XL |
1207 | } |
1208 | } | |
1209 | } | |
1210 | ||
fc512014 | 1211 | if let Some(ty) = ty.visit_with(&mut ProhibitOpaqueTypes { cx: self.cx }).break_value() { |
dfeec247 | 1212 | self.emit_ffi_unsafe_type_lint(ty, sp, "opaque types have no C equivalent", None); |
e1599b0c XL |
1213 | true |
1214 | } else { | |
1215 | false | |
b039eaaf SL |
1216 | } |
1217 | } | |
1218 | ||
f035d41b XL |
1219 | fn check_type_for_ffi_and_report_errors( |
1220 | &mut self, | |
1221 | sp: Span, | |
1222 | ty: Ty<'tcx>, | |
1223 | is_static: bool, | |
1224 | is_return_type: bool, | |
1225 | ) { | |
e1599b0c XL |
1226 | // We have to check for opaque types before `normalize_erasing_regions`, |
1227 | // which will replace opaque types with their underlying concrete type. | |
1228 | if self.check_for_opaque_ty(sp, ty) { | |
1229 | // We've already emitted an error due to an opaque type. | |
1230 | return; | |
1231 | } | |
1232 | ||
54a0048b SL |
1233 | // it is only OK to use this function because extern fns cannot have |
1234 | // any generic types right now: | |
f035d41b XL |
1235 | let ty = self.cx.tcx.normalize_erasing_regions(self.cx.param_env, ty); |
1236 | ||
1237 | // C doesn't really support passing arrays by value - the only way to pass an array by value | |
1238 | // is through a struct. So, first test that the top level isn't an array, and then | |
1239 | // recursively check the types inside. | |
60c5eb7d XL |
1240 | if !is_static && self.check_for_array_ty(sp, ty) { |
1241 | return; | |
1242 | } | |
b039eaaf | 1243 | |
f035d41b XL |
1244 | // Don't report FFI errors for unit return types. This check exists here, and not in |
1245 | // `check_foreign_fn` (where it would make more sense) so that normalization has definitely | |
1246 | // happened. | |
1247 | if is_return_type && ty.is_unit() { | |
1248 | return; | |
1249 | } | |
1250 | ||
0bf4aa26 | 1251 | match self.check_type_for_ffi(&mut FxHashSet::default(), ty) { |
b039eaaf | 1252 | FfiResult::FfiSafe => {} |
0531ce1d | 1253 | FfiResult::FfiPhantom(ty) => { |
e1599b0c | 1254 | self.emit_ffi_unsafe_type_lint(ty, sp, "composed only of `PhantomData`", None); |
9e0c209e | 1255 | } |
f035d41b XL |
1256 | // If `ty` is a `repr(transparent)` newtype, and the non-zero-sized type is a generic |
1257 | // argument, which after substitution, is `()`, then this branch can be hit. | |
3dfed10e | 1258 | FfiResult::FfiUnsafe { ty, .. } if is_return_type && ty.is_unit() => {} |
e1599b0c | 1259 | FfiResult::FfiUnsafe { ty, reason, help } => { |
f035d41b | 1260 | self.emit_ffi_unsafe_type_lint(ty, sp, &reason, help.as_deref()); |
b039eaaf SL |
1261 | } |
1262 | } | |
1263 | } | |
b039eaaf | 1264 | |
dfeec247 | 1265 | fn check_foreign_fn(&mut self, id: hir::HirId, decl: &hir::FnDecl<'_>) { |
416331ca | 1266 | let def_id = self.cx.tcx.hir().local_def_id(id); |
041b39d2 | 1267 | let sig = self.cx.tcx.fn_sig(def_id); |
fc512014 | 1268 | let sig = self.cx.tcx.erase_late_bound_regions(sig); |
54a0048b | 1269 | |
cdc7bbd5 | 1270 | for (input_ty, input_hir) in iter::zip(sig.inputs(), decl.inputs) { |
5099ac24 | 1271 | self.check_type_for_ffi_and_report_errors(input_hir.span, *input_ty, false, false); |
54a0048b SL |
1272 | } |
1273 | ||
74b04a01 | 1274 | if let hir::FnRetTy::Return(ref ret_hir) = decl.output { |
476ff2be | 1275 | let ret_ty = sig.output(); |
f035d41b | 1276 | self.check_type_for_ffi_and_report_errors(ret_hir.span, ret_ty, false, true); |
b039eaaf SL |
1277 | } |
1278 | } | |
54a0048b | 1279 | |
532ac7d7 | 1280 | fn check_foreign_static(&mut self, id: hir::HirId, span: Span) { |
416331ca | 1281 | let def_id = self.cx.tcx.hir().local_def_id(id); |
7cac9316 | 1282 | let ty = self.cx.tcx.type_of(def_id); |
f035d41b | 1283 | self.check_type_for_ffi_and_report_errors(span, ty, true, false); |
54a0048b | 1284 | } |
b039eaaf | 1285 | |
3dfed10e | 1286 | fn is_internal_abi(&self, abi: SpecAbi) -> bool { |
29967ef6 XL |
1287 | matches!( |
1288 | abi, | |
1289 | SpecAbi::Rust | SpecAbi::RustCall | SpecAbi::RustIntrinsic | SpecAbi::PlatformIntrinsic | |
1290 | ) | |
f035d41b XL |
1291 | } |
1292 | } | |
1293 | ||
1294 | impl<'tcx> LateLintPass<'tcx> for ImproperCTypesDeclarations { | |
1295 | fn check_foreign_item(&mut self, cx: &LateContext<'_>, it: &hir::ForeignItem<'_>) { | |
3dfed10e | 1296 | let mut vis = ImproperCTypesVisitor { cx, mode: CItemKind::Declaration }; |
6a06907d | 1297 | let abi = cx.tcx.hir().get_foreign_abi(it.hir_id()); |
f035d41b XL |
1298 | |
1299 | if !vis.is_internal_abi(abi) { | |
e74abb32 | 1300 | match it.kind { |
b7449926 | 1301 | hir::ForeignItemKind::Fn(ref decl, _, _) => { |
6a06907d | 1302 | vis.check_foreign_fn(it.hir_id(), decl); |
b7449926 XL |
1303 | } |
1304 | hir::ForeignItemKind::Static(ref ty, _) => { | |
6a06907d | 1305 | vis.check_foreign_static(it.hir_id(), ty.span); |
b039eaaf | 1306 | } |
dfeec247 | 1307 | hir::ForeignItemKind::Type => (), |
b039eaaf | 1308 | } |
b039eaaf SL |
1309 | } |
1310 | } | |
1311 | } | |
5bcae85e | 1312 | |
f035d41b XL |
1313 | impl<'tcx> LateLintPass<'tcx> for ImproperCTypesDefinitions { |
1314 | fn check_fn( | |
1315 | &mut self, | |
1316 | cx: &LateContext<'tcx>, | |
1317 | kind: hir::intravisit::FnKind<'tcx>, | |
1318 | decl: &'tcx hir::FnDecl<'_>, | |
1319 | _: &'tcx hir::Body<'_>, | |
1320 | _: Span, | |
1321 | hir_id: hir::HirId, | |
1322 | ) { | |
1323 | use hir::intravisit::FnKind; | |
1324 | ||
1325 | let abi = match kind { | |
1326 | FnKind::ItemFn(_, _, header, ..) => header.abi, | |
1327 | FnKind::Method(_, sig, ..) => sig.header.abi, | |
1328 | _ => return, | |
1329 | }; | |
1330 | ||
3dfed10e | 1331 | let mut vis = ImproperCTypesVisitor { cx, mode: CItemKind::Definition }; |
f035d41b XL |
1332 | if !vis.is_internal_abi(abi) { |
1333 | vis.check_foreign_fn(hir_id, decl); | |
1334 | } | |
1335 | } | |
1336 | } | |
1337 | ||
532ac7d7 | 1338 | declare_lint_pass!(VariantSizeDifferences => [VARIANT_SIZE_DIFFERENCES]); |
5bcae85e | 1339 | |
f035d41b XL |
1340 | impl<'tcx> LateLintPass<'tcx> for VariantSizeDifferences { |
1341 | fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) { | |
e74abb32 | 1342 | if let hir::ItemKind::Enum(ref enum_definition, _) = it.kind { |
6a06907d | 1343 | let t = cx.tcx.type_of(it.def_id); |
fc512014 | 1344 | let ty = cx.tcx.erase_regions(t); |
5e7ed085 | 1345 | let Ok(layout) = cx.layout_of(ty) else { return }; |
a2a8927a | 1346 | let Variants::Multiple { |
c295e0f8 | 1347 | tag_encoding: TagEncoding::Direct, tag, ref variants, .. |
a2a8927a XL |
1348 | } = &layout.variants else { |
1349 | return | |
532ac7d7 XL |
1350 | }; |
1351 | ||
04454e1e | 1352 | let tag_size = tag.size(&cx.tcx).bytes(); |
532ac7d7 | 1353 | |
dfeec247 XL |
1354 | debug!( |
1355 | "enum `{}` is {} bytes large with layout:\n{:#?}", | |
1356 | t, | |
1357 | layout.size.bytes(), | |
1358 | layout | |
1359 | ); | |
532ac7d7 | 1360 | |
cdc7bbd5 | 1361 | let (largest, slargest, largest_index) = iter::zip(enum_definition.variants, variants) |
532ac7d7 | 1362 | .map(|(variant, variant_layout)| { |
f035d41b | 1363 | // Subtract the size of the enum tag. |
5e7ed085 | 1364 | let bytes = variant_layout.size().bytes().saturating_sub(tag_size); |
532ac7d7 | 1365 | |
dfeec247 | 1366 | debug!("- variant `{}` is {} bytes large", variant.ident, bytes); |
532ac7d7 XL |
1367 | bytes |
1368 | }) | |
1369 | .enumerate() | |
dfeec247 XL |
1370 | .fold((0, 0, 0), |(l, s, li), (idx, size)| { |
1371 | if size > l { | |
1372 | (size, l, idx) | |
1373 | } else if size > s { | |
1374 | (l, size, li) | |
1375 | } else { | |
1376 | (l, s, li) | |
1377 | } | |
532ac7d7 XL |
1378 | }); |
1379 | ||
1380 | // We only warn if the largest variant is at least thrice as large as | |
1381 | // the second-largest. | |
1382 | if largest > slargest * 3 && slargest > 0 { | |
74b04a01 | 1383 | cx.struct_span_lint( |
dfeec247 XL |
1384 | VARIANT_SIZE_DIFFERENCES, |
1385 | enum_definition.variants[largest_index].span, | |
74b04a01 XL |
1386 | |lint| { |
1387 | lint.build(&format!( | |
1388 | "enum variant is more than three times \ | |
532ac7d7 | 1389 | larger ({} bytes) than the next largest", |
74b04a01 XL |
1390 | largest |
1391 | )) | |
5e7ed085 | 1392 | .emit(); |
74b04a01 | 1393 | }, |
dfeec247 | 1394 | ); |
5bcae85e SL |
1395 | } |
1396 | } | |
1397 | } | |
1398 | } | |
94222f64 XL |
1399 | |
1400 | declare_lint! { | |
1401 | /// The `invalid_atomic_ordering` lint detects passing an `Ordering` | |
1402 | /// to an atomic operation that does not support that ordering. | |
1403 | /// | |
1404 | /// ### Example | |
1405 | /// | |
1406 | /// ```rust,compile_fail | |
1407 | /// # use core::sync::atomic::{AtomicU8, Ordering}; | |
1408 | /// let atom = AtomicU8::new(0); | |
1409 | /// let value = atom.load(Ordering::Release); | |
1410 | /// # let _ = value; | |
1411 | /// ``` | |
1412 | /// | |
1413 | /// {{produces}} | |
1414 | /// | |
1415 | /// ### Explanation | |
1416 | /// | |
1417 | /// Some atomic operations are only supported for a subset of the | |
1418 | /// `atomic::Ordering` variants. Passing an unsupported variant will cause | |
1419 | /// an unconditional panic at runtime, which is detected by this lint. | |
1420 | /// | |
1421 | /// This lint will trigger in the following cases: (where `AtomicType` is an | |
1422 | /// atomic type from `core::sync::atomic`, such as `AtomicBool`, | |
1423 | /// `AtomicPtr`, `AtomicUsize`, or any of the other integer atomics). | |
1424 | /// | |
1425 | /// - Passing `Ordering::Acquire` or `Ordering::AcqRel` to | |
1426 | /// `AtomicType::store`. | |
1427 | /// | |
1428 | /// - Passing `Ordering::Release` or `Ordering::AcqRel` to | |
1429 | /// `AtomicType::load`. | |
1430 | /// | |
1431 | /// - Passing `Ordering::Relaxed` to `core::sync::atomic::fence` or | |
1432 | /// `core::sync::atomic::compiler_fence`. | |
1433 | /// | |
1434 | /// - Passing `Ordering::Release` or `Ordering::AcqRel` as the failure | |
1435 | /// ordering for any of `AtomicType::compare_exchange`, | |
1436 | /// `AtomicType::compare_exchange_weak`, or `AtomicType::fetch_update`. | |
1437 | /// | |
1438 | /// - Passing in a pair of orderings to `AtomicType::compare_exchange`, | |
1439 | /// `AtomicType::compare_exchange_weak`, or `AtomicType::fetch_update` | |
1440 | /// where the failure ordering is stronger than the success ordering. | |
1441 | INVALID_ATOMIC_ORDERING, | |
1442 | Deny, | |
1443 | "usage of invalid atomic ordering in atomic operations and memory fences" | |
1444 | } | |
1445 | ||
1446 | declare_lint_pass!(InvalidAtomicOrdering => [INVALID_ATOMIC_ORDERING]); | |
1447 | ||
1448 | impl InvalidAtomicOrdering { | |
1449 | fn inherent_atomic_method_call<'hir>( | |
1450 | cx: &LateContext<'_>, | |
1451 | expr: &Expr<'hir>, | |
1452 | recognized_names: &[Symbol], // used for fast path calculation | |
1453 | ) -> Option<(Symbol, &'hir [Expr<'hir>])> { | |
1454 | const ATOMIC_TYPES: &[Symbol] = &[ | |
1455 | sym::AtomicBool, | |
1456 | sym::AtomicPtr, | |
1457 | sym::AtomicUsize, | |
1458 | sym::AtomicU8, | |
1459 | sym::AtomicU16, | |
1460 | sym::AtomicU32, | |
1461 | sym::AtomicU64, | |
1462 | sym::AtomicU128, | |
1463 | sym::AtomicIsize, | |
1464 | sym::AtomicI8, | |
1465 | sym::AtomicI16, | |
1466 | sym::AtomicI32, | |
1467 | sym::AtomicI64, | |
1468 | sym::AtomicI128, | |
1469 | ]; | |
5e7ed085 FG |
1470 | if let ExprKind::MethodCall(ref method_path, args, _) = &expr.kind |
1471 | && recognized_names.contains(&method_path.ident.name) | |
1472 | && let Some(m_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id) | |
1473 | && let Some(impl_did) = cx.tcx.impl_of_method(m_def_id) | |
1474 | && let Some(adt) = cx.tcx.type_of(impl_did).ty_adt_def() | |
94222f64 | 1475 | // skip extension traits, only lint functions from the standard library |
5e7ed085 | 1476 | && cx.tcx.trait_id_of_impl(impl_did).is_none() |
04454e1e | 1477 | && let parent = cx.tcx.parent(adt.did()) |
5e7ed085 FG |
1478 | && cx.tcx.is_diagnostic_item(sym::atomic_mod, parent) |
1479 | && ATOMIC_TYPES.contains(&cx.tcx.item_name(adt.did())) | |
1480 | { | |
1481 | return Some((method_path.ident.name, args)); | |
94222f64 XL |
1482 | } |
1483 | None | |
1484 | } | |
1485 | ||
1486 | fn matches_ordering(cx: &LateContext<'_>, did: DefId, orderings: &[Symbol]) -> bool { | |
1487 | let tcx = cx.tcx; | |
1488 | let atomic_ordering = tcx.get_diagnostic_item(sym::Ordering); | |
1489 | orderings.iter().any(|ordering| { | |
1490 | tcx.item_name(did) == *ordering && { | |
1491 | let parent = tcx.parent(did); | |
04454e1e | 1492 | Some(parent) == atomic_ordering |
94222f64 | 1493 | // needed in case this is a ctor, not a variant |
04454e1e | 1494 | || tcx.opt_parent(parent) == atomic_ordering |
94222f64 XL |
1495 | } |
1496 | }) | |
1497 | } | |
1498 | ||
1499 | fn opt_ordering_defid(cx: &LateContext<'_>, ord_arg: &Expr<'_>) -> Option<DefId> { | |
1500 | if let ExprKind::Path(ref ord_qpath) = ord_arg.kind { | |
1501 | cx.qpath_res(ord_qpath, ord_arg.hir_id).opt_def_id() | |
1502 | } else { | |
1503 | None | |
1504 | } | |
1505 | } | |
1506 | ||
1507 | fn check_atomic_load_store(cx: &LateContext<'_>, expr: &Expr<'_>) { | |
1508 | use rustc_hir::def::{DefKind, Res}; | |
1509 | use rustc_hir::QPath; | |
5e7ed085 FG |
1510 | if let Some((method, args)) = Self::inherent_atomic_method_call(cx, expr, &[sym::load, sym::store]) |
1511 | && let Some((ordering_arg, invalid_ordering)) = match method { | |
94222f64 XL |
1512 | sym::load => Some((&args[1], sym::Release)), |
1513 | sym::store => Some((&args[2], sym::Acquire)), | |
1514 | _ => None, | |
94222f64 | 1515 | } |
5e7ed085 FG |
1516 | && let ExprKind::Path(QPath::Resolved(_, path)) = ordering_arg.kind |
1517 | && let Res::Def(DefKind::Ctor(..), ctor_id) = path.res | |
1518 | && Self::matches_ordering(cx, ctor_id, &[invalid_ordering, sym::AcqRel]) | |
1519 | { | |
1520 | cx.struct_span_lint(INVALID_ATOMIC_ORDERING, ordering_arg.span, |diag| { | |
1521 | if method == sym::load { | |
1522 | diag.build("atomic loads cannot have `Release` or `AcqRel` ordering") | |
1523 | .help("consider using ordering modes `Acquire`, `SeqCst` or `Relaxed`") | |
1524 | .emit() | |
1525 | } else { | |
1526 | debug_assert_eq!(method, sym::store); | |
1527 | diag.build("atomic stores cannot have `Acquire` or `AcqRel` ordering") | |
1528 | .help("consider using ordering modes `Release`, `SeqCst` or `Relaxed`") | |
1529 | .emit(); | |
1530 | } | |
1531 | }); | |
94222f64 XL |
1532 | } |
1533 | } | |
1534 | ||
1535 | fn check_memory_fence(cx: &LateContext<'_>, expr: &Expr<'_>) { | |
5e7ed085 FG |
1536 | if let ExprKind::Call(ref func, ref args) = expr.kind |
1537 | && let ExprKind::Path(ref func_qpath) = func.kind | |
1538 | && let Some(def_id) = cx.qpath_res(func_qpath, func.hir_id).opt_def_id() | |
1539 | && matches!(cx.tcx.get_diagnostic_name(def_id), Some(sym::fence | sym::compiler_fence)) | |
1540 | && let ExprKind::Path(ref ordering_qpath) = &args[0].kind | |
1541 | && let Some(ordering_def_id) = cx.qpath_res(ordering_qpath, args[0].hir_id).opt_def_id() | |
1542 | && Self::matches_ordering(cx, ordering_def_id, &[sym::Relaxed]) | |
1543 | { | |
1544 | cx.struct_span_lint(INVALID_ATOMIC_ORDERING, args[0].span, |diag| { | |
1545 | diag.build("memory fences cannot have `Relaxed` ordering") | |
1546 | .help("consider using ordering modes `Acquire`, `Release`, `AcqRel` or `SeqCst`") | |
1547 | .emit(); | |
1548 | }); | |
94222f64 XL |
1549 | } |
1550 | } | |
1551 | ||
1552 | fn check_atomic_compare_exchange(cx: &LateContext<'_>, expr: &Expr<'_>) { | |
5e7ed085 FG |
1553 | if let Some((method, args)) = Self::inherent_atomic_method_call(cx, expr, &[sym::fetch_update, sym::compare_exchange, sym::compare_exchange_weak]) |
1554 | && let Some((success_order_arg, failure_order_arg)) = match method { | |
94222f64 XL |
1555 | sym::fetch_update => Some((&args[1], &args[2])), |
1556 | sym::compare_exchange | sym::compare_exchange_weak => Some((&args[3], &args[4])), | |
1557 | _ => None, | |
5e7ed085 FG |
1558 | } |
1559 | && let Some(fail_ordering_def_id) = Self::opt_ordering_defid(cx, failure_order_arg) | |
1560 | { | |
1561 | // Helper type holding on to some checking and error reporting data. Has | |
1562 | // - (success ordering, | |
1563 | // - list of failure orderings forbidden by the success order, | |
1564 | // - suggestion message) | |
1565 | type OrdLintInfo = (Symbol, &'static [Symbol], &'static str); | |
1566 | const RELAXED: OrdLintInfo = (sym::Relaxed, &[sym::SeqCst, sym::Acquire], "ordering mode `Relaxed`"); | |
1567 | const ACQUIRE: OrdLintInfo = (sym::Acquire, &[sym::SeqCst], "ordering modes `Acquire` or `Relaxed`"); | |
1568 | const SEQ_CST: OrdLintInfo = (sym::SeqCst, &[], "ordering modes `Acquire`, `SeqCst` or `Relaxed`"); | |
1569 | const RELEASE: OrdLintInfo = (sym::Release, RELAXED.1, RELAXED.2); | |
1570 | const ACQREL: OrdLintInfo = (sym::AcqRel, ACQUIRE.1, ACQUIRE.2); | |
1571 | const SEARCH: [OrdLintInfo; 5] = [RELAXED, ACQUIRE, SEQ_CST, RELEASE, ACQREL]; | |
1572 | ||
1573 | let success_lint_info = Self::opt_ordering_defid(cx, success_order_arg) | |
1574 | .and_then(|success_ord_def_id| -> Option<OrdLintInfo> { | |
1575 | SEARCH | |
1576 | .iter() | |
1577 | .copied() | |
1578 | .find(|(ordering, ..)| { | |
1579 | Self::matches_ordering(cx, success_ord_def_id, &[*ordering]) | |
1580 | }) | |
1581 | }); | |
1582 | if Self::matches_ordering(cx, fail_ordering_def_id, &[sym::Release, sym::AcqRel]) { | |
1583 | // If we don't know the success order is, use what we'd suggest | |
1584 | // if it were maximally permissive. | |
1585 | let suggested = success_lint_info.unwrap_or(SEQ_CST).2; | |
1586 | cx.struct_span_lint(INVALID_ATOMIC_ORDERING, failure_order_arg.span, |diag| { | |
1587 | let msg = format!( | |
1588 | "{}'s failure ordering may not be `Release` or `AcqRel`", | |
1589 | method, | |
1590 | ); | |
1591 | diag.build(&msg) | |
1592 | .help(&format!("consider using {} instead", suggested)) | |
1593 | .emit(); | |
1594 | }); | |
1595 | } else if let Some((success_ord, bad_ords_given_success, suggested)) = success_lint_info { | |
1596 | if Self::matches_ordering(cx, fail_ordering_def_id, bad_ords_given_success) { | |
94222f64 XL |
1597 | cx.struct_span_lint(INVALID_ATOMIC_ORDERING, failure_order_arg.span, |diag| { |
1598 | let msg = format!( | |
5e7ed085 | 1599 | "{}'s failure ordering may not be stronger than the success ordering of `{}`", |
94222f64 | 1600 | method, |
5e7ed085 | 1601 | success_ord, |
94222f64 XL |
1602 | ); |
1603 | diag.build(&msg) | |
1604 | .help(&format!("consider using {} instead", suggested)) | |
1605 | .emit(); | |
1606 | }); | |
94222f64 XL |
1607 | } |
1608 | } | |
1609 | } | |
1610 | } | |
1611 | } | |
1612 | ||
1613 | impl<'tcx> LateLintPass<'tcx> for InvalidAtomicOrdering { | |
1614 | fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { | |
1615 | Self::check_atomic_load_store(cx, expr); | |
1616 | Self::check_memory_fence(cx, expr); | |
1617 | Self::check_atomic_compare_exchange(cx, expr); | |
1618 | } | |
1619 | } |