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Commit | Line | Data |
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9cc50fc6 SL |
1 | #![allow(non_snake_case)] |
2 | ||
dfeec247 | 3 | use crate::{LateContext, LateLintPass, LintContext}; |
3dfed10e | 4 | use rustc_ast as ast; |
74b04a01 | 5 | use rustc_attr as attr; |
dfeec247 XL |
6 | use rustc_data_structures::fx::FxHashSet; |
7 | use rustc_errors::Applicability; | |
8 | use rustc_hir as hir; | |
dfeec247 | 9 | use rustc_hir::{is_range_literal, ExprKind, Node}; |
e74abb32 | 10 | use rustc_index::vec::Idx; |
ba9703b0 XL |
11 | use rustc_middle::mir::interpret::{sign_extend, truncate}; |
12 | use rustc_middle::ty::layout::{IntegerExt, SizeSkeleton}; | |
13 | use rustc_middle::ty::subst::SubstsRef; | |
f035d41b | 14 | use rustc_middle::ty::{self, AdtKind, Ty, TypeFoldable}; |
dfeec247 XL |
15 | use rustc_span::source_map; |
16 | use rustc_span::symbol::sym; | |
f035d41b | 17 | use rustc_span::{Span, DUMMY_SP}; |
3dfed10e | 18 | use rustc_target::abi::Abi; |
f035d41b | 19 | use rustc_target::abi::{Integer, LayoutOf, TagEncoding, VariantIdx, Variants}; |
3dfed10e | 20 | use rustc_target::spec::abi::Abi as SpecAbi; |
9fa01778 | 21 | |
dfeec247 | 22 | use std::cmp; |
3dfed10e | 23 | use tracing::debug; |
9fa01778 | 24 | |
b039eaaf SL |
25 | declare_lint! { |
26 | UNUSED_COMPARISONS, | |
27 | Warn, | |
28 | "comparisons made useless by limits of the types involved" | |
29 | } | |
30 | ||
31 | declare_lint! { | |
32 | OVERFLOWING_LITERALS, | |
9fa01778 XL |
33 | Deny, |
34 | "literal out of range for its type" | |
b039eaaf SL |
35 | } |
36 | ||
5bcae85e SL |
37 | declare_lint! { |
38 | VARIANT_SIZE_DIFFERENCES, | |
39 | Allow, | |
40 | "detects enums with widely varying variant sizes" | |
41 | } | |
42 | ||
b039eaaf SL |
43 | #[derive(Copy, Clone)] |
44 | pub struct TypeLimits { | |
45 | /// Id of the last visited negated expression | |
ba9703b0 | 46 | negated_expr_id: Option<hir::HirId>, |
b039eaaf SL |
47 | } |
48 | ||
532ac7d7 XL |
49 | impl_lint_pass!(TypeLimits => [UNUSED_COMPARISONS, OVERFLOWING_LITERALS]); |
50 | ||
b039eaaf SL |
51 | impl TypeLimits { |
52 | pub fn new() -> TypeLimits { | |
ba9703b0 | 53 | TypeLimits { negated_expr_id: None } |
b039eaaf SL |
54 | } |
55 | } | |
56 | ||
48663c56 XL |
57 | /// Attempts to special-case the overflowing literal lint when it occurs as a range endpoint. |
58 | /// Returns `true` iff the lint was overridden. | |
f035d41b XL |
59 | fn lint_overflowing_range_endpoint<'tcx>( |
60 | cx: &LateContext<'tcx>, | |
48663c56 XL |
61 | lit: &hir::Lit, |
62 | lit_val: u128, | |
63 | max: u128, | |
dfeec247 XL |
64 | expr: &'tcx hir::Expr<'tcx>, |
65 | parent_expr: &'tcx hir::Expr<'tcx>, | |
60c5eb7d | 66 | ty: &str, |
48663c56 XL |
67 | ) -> bool { |
68 | // We only want to handle exclusive (`..`) ranges, | |
69 | // which are represented as `ExprKind::Struct`. | |
74b04a01 | 70 | let mut overwritten = false; |
e74abb32 | 71 | if let ExprKind::Struct(_, eps, _) = &parent_expr.kind { |
416331ca XL |
72 | if eps.len() != 2 { |
73 | return false; | |
74 | } | |
48663c56 XL |
75 | // We can suggest using an inclusive range |
76 | // (`..=`) instead only if it is the `end` that is | |
77 | // overflowing and only by 1. | |
78 | if eps[1].expr.hir_id == expr.hir_id && lit_val - 1 == max { | |
74b04a01 XL |
79 | cx.struct_span_lint(OVERFLOWING_LITERALS, parent_expr.span, |lint| { |
80 | let mut err = lint.build(&format!("range endpoint is out of range for `{}`", ty)); | |
81 | if let Ok(start) = cx.sess().source_map().span_to_snippet(eps[0].span) { | |
82 | use ast::{LitIntType, LitKind}; | |
83 | // We need to preserve the literal's suffix, | |
84 | // as it may determine typing information. | |
85 | let suffix = match lit.node { | |
86 | LitKind::Int(_, LitIntType::Signed(s)) => s.name_str().to_string(), | |
87 | LitKind::Int(_, LitIntType::Unsigned(s)) => s.name_str().to_string(), | |
88 | LitKind::Int(_, LitIntType::Unsuffixed) => "".to_string(), | |
89 | _ => bug!(), | |
90 | }; | |
91 | let suggestion = format!("{}..={}{}", start, lit_val - 1, suffix); | |
92 | err.span_suggestion( | |
93 | parent_expr.span, | |
94 | &"use an inclusive range instead", | |
95 | suggestion, | |
96 | Applicability::MachineApplicable, | |
97 | ); | |
98 | err.emit(); | |
99 | overwritten = true; | |
100 | } | |
101 | }); | |
48663c56 XL |
102 | } |
103 | } | |
74b04a01 | 104 | overwritten |
48663c56 XL |
105 | } |
106 | ||
107 | // For `isize` & `usize`, be conservative with the warnings, so that the | |
108 | // warnings are consistent between 32- and 64-bit platforms. | |
109 | fn int_ty_range(int_ty: ast::IntTy) -> (i128, i128) { | |
110 | match int_ty { | |
f035d41b XL |
111 | ast::IntTy::Isize => (i64::MIN as i128, i64::MAX as i128), |
112 | ast::IntTy::I8 => (i8::MIN as i64 as i128, i8::MAX as i128), | |
113 | ast::IntTy::I16 => (i16::MIN as i64 as i128, i16::MAX as i128), | |
114 | ast::IntTy::I32 => (i32::MIN as i64 as i128, i32::MAX as i128), | |
115 | ast::IntTy::I64 => (i64::MIN as i128, i64::MAX as i128), | |
116 | ast::IntTy::I128 => (i128::MIN as i128, i128::MAX), | |
48663c56 XL |
117 | } |
118 | } | |
119 | ||
120 | fn uint_ty_range(uint_ty: ast::UintTy) -> (u128, u128) { | |
121 | match uint_ty { | |
f035d41b XL |
122 | ast::UintTy::Usize => (u64::MIN as u128, u64::MAX as u128), |
123 | ast::UintTy::U8 => (u8::MIN as u128, u8::MAX as u128), | |
124 | ast::UintTy::U16 => (u16::MIN as u128, u16::MAX as u128), | |
125 | ast::UintTy::U32 => (u32::MIN as u128, u32::MAX as u128), | |
126 | ast::UintTy::U64 => (u64::MIN as u128, u64::MAX as u128), | |
127 | ast::UintTy::U128 => (u128::MIN, u128::MAX), | |
48663c56 XL |
128 | } |
129 | } | |
130 | ||
f035d41b | 131 | fn get_bin_hex_repr(cx: &LateContext<'_>, lit: &hir::Lit) -> Option<String> { |
48663c56 XL |
132 | let src = cx.sess().source_map().span_to_snippet(lit.span).ok()?; |
133 | let firstch = src.chars().next()?; | |
134 | ||
135 | if firstch == '0' { | |
136 | match src.chars().nth(1) { | |
ba9703b0 | 137 | Some('x' | 'b') => return Some(src), |
48663c56 XL |
138 | _ => return None, |
139 | } | |
140 | } | |
141 | ||
142 | None | |
143 | } | |
144 | ||
145 | fn report_bin_hex_error( | |
f035d41b | 146 | cx: &LateContext<'_>, |
dfeec247 | 147 | expr: &hir::Expr<'_>, |
48663c56 XL |
148 | ty: attr::IntType, |
149 | repr_str: String, | |
150 | val: u128, | |
151 | negative: bool, | |
152 | ) { | |
ba9703b0 | 153 | let size = Integer::from_attr(&cx.tcx, ty).size(); |
74b04a01 XL |
154 | cx.struct_span_lint(OVERFLOWING_LITERALS, expr.span, |lint| { |
155 | let (t, actually) = match ty { | |
156 | attr::IntType::SignedInt(t) => { | |
157 | let actually = sign_extend(val, size) as i128; | |
158 | (t.name_str(), actually.to_string()) | |
159 | } | |
160 | attr::IntType::UnsignedInt(t) => { | |
161 | let actually = truncate(val, size); | |
162 | (t.name_str(), actually.to_string()) | |
163 | } | |
164 | }; | |
165 | let mut err = lint.build(&format!("literal out of range for {}", t)); | |
166 | err.note(&format!( | |
167 | "the literal `{}` (decimal `{}`) does not fit into \ | |
ba9703b0 | 168 | the type `{}` and will become `{}{}`", |
74b04a01 XL |
169 | repr_str, val, t, actually, t |
170 | )); | |
f035d41b | 171 | if let Some(sugg_ty) = |
3dfed10e | 172 | get_type_suggestion(&cx.typeck_results().node_type(expr.hir_id), val, negative) |
74b04a01 XL |
173 | { |
174 | if let Some(pos) = repr_str.chars().position(|c| c == 'i' || c == 'u') { | |
175 | let (sans_suffix, _) = repr_str.split_at(pos); | |
176 | err.span_suggestion( | |
177 | expr.span, | |
178 | &format!("consider using `{}` instead", sugg_ty), | |
179 | format!("{}{}", sans_suffix, sugg_ty), | |
180 | Applicability::MachineApplicable, | |
181 | ); | |
182 | } else { | |
183 | err.help(&format!("consider using `{}` instead", sugg_ty)); | |
184 | } | |
48663c56 | 185 | } |
74b04a01 XL |
186 | err.emit(); |
187 | }); | |
48663c56 XL |
188 | } |
189 | ||
190 | // This function finds the next fitting type and generates a suggestion string. | |
191 | // It searches for fitting types in the following way (`X < Y`): | |
192 | // - `iX`: if literal fits in `uX` => `uX`, else => `iY` | |
193 | // - `-iX` => `iY` | |
194 | // - `uX` => `uY` | |
195 | // | |
196 | // No suggestion for: `isize`, `usize`. | |
60c5eb7d | 197 | fn get_type_suggestion(t: Ty<'_>, val: u128, negative: bool) -> Option<&'static str> { |
3dfed10e XL |
198 | use rustc_ast::IntTy::*; |
199 | use rustc_ast::UintTy::*; | |
48663c56 XL |
200 | macro_rules! find_fit { |
201 | ($ty:expr, $val:expr, $negative:expr, | |
202 | $($type:ident => [$($utypes:expr),*] => [$($itypes:expr),*]),+) => { | |
203 | { | |
204 | let _neg = if negative { 1 } else { 0 }; | |
205 | match $ty { | |
206 | $($type => { | |
207 | $(if !negative && val <= uint_ty_range($utypes).1 { | |
60c5eb7d | 208 | return Some($utypes.name_str()) |
48663c56 XL |
209 | })* |
210 | $(if val <= int_ty_range($itypes).1 as u128 + _neg { | |
60c5eb7d | 211 | return Some($itypes.name_str()) |
48663c56 XL |
212 | })* |
213 | None | |
dc9dc135 | 214 | },)+ |
48663c56 XL |
215 | _ => None |
216 | } | |
217 | } | |
218 | } | |
219 | } | |
e74abb32 | 220 | match t.kind { |
48663c56 XL |
221 | ty::Int(i) => find_fit!(i, val, negative, |
222 | I8 => [U8] => [I16, I32, I64, I128], | |
223 | I16 => [U16] => [I32, I64, I128], | |
224 | I32 => [U32] => [I64, I128], | |
225 | I64 => [U64] => [I128], | |
226 | I128 => [U128] => []), | |
227 | ty::Uint(u) => find_fit!(u, val, negative, | |
228 | U8 => [U8, U16, U32, U64, U128] => [], | |
229 | U16 => [U16, U32, U64, U128] => [], | |
230 | U32 => [U32, U64, U128] => [], | |
231 | U64 => [U64, U128] => [], | |
232 | U128 => [U128] => []), | |
233 | _ => None, | |
234 | } | |
235 | } | |
236 | ||
f035d41b XL |
237 | fn lint_int_literal<'tcx>( |
238 | cx: &LateContext<'tcx>, | |
48663c56 | 239 | type_limits: &TypeLimits, |
dfeec247 | 240 | e: &'tcx hir::Expr<'tcx>, |
48663c56 XL |
241 | lit: &hir::Lit, |
242 | t: ast::IntTy, | |
243 | v: u128, | |
244 | ) { | |
60c5eb7d | 245 | let int_type = t.normalize(cx.sess().target.ptr_width); |
ba9703b0 | 246 | let (min, max) = int_ty_range(int_type); |
48663c56 | 247 | let max = max as u128; |
ba9703b0 | 248 | let negative = type_limits.negated_expr_id == Some(e.hir_id); |
48663c56 XL |
249 | |
250 | // Detect literal value out of range [min, max] inclusive | |
251 | // avoiding use of -min to prevent overflow/panic | |
252 | if (negative && v > max + 1) || (!negative && v > max) { | |
253 | if let Some(repr_str) = get_bin_hex_repr(cx, lit) { | |
dfeec247 | 254 | report_bin_hex_error(cx, e, attr::IntType::SignedInt(t), repr_str, v, negative); |
48663c56 XL |
255 | return; |
256 | } | |
257 | ||
dc9dc135 XL |
258 | let par_id = cx.tcx.hir().get_parent_node(e.hir_id); |
259 | if let Node::Expr(par_e) = cx.tcx.hir().get(par_id) { | |
e74abb32 | 260 | if let hir::ExprKind::Struct(..) = par_e.kind { |
3dfed10e | 261 | if is_range_literal(par_e) |
60c5eb7d | 262 | && lint_overflowing_range_endpoint(cx, lit, v, max, e, par_e, t.name_str()) |
48663c56 XL |
263 | { |
264 | // The overflowing literal lint was overridden. | |
265 | return; | |
266 | } | |
267 | } | |
268 | } | |
269 | ||
74b04a01 | 270 | cx.struct_span_lint(OVERFLOWING_LITERALS, e.span, |lint| { |
ba9703b0 XL |
271 | lint.build(&format!("literal out of range for `{}`", t.name_str())) |
272 | .note(&format!( | |
273 | "the literal `{}` does not fit into the type `{}` whose range is `{}..={}`", | |
274 | cx.sess() | |
275 | .source_map() | |
276 | .span_to_snippet(lit.span) | |
277 | .expect("must get snippet from literal"), | |
278 | t.name_str(), | |
279 | min, | |
280 | max, | |
281 | )) | |
282 | .emit(); | |
74b04a01 | 283 | }); |
48663c56 XL |
284 | } |
285 | } | |
286 | ||
f035d41b XL |
287 | fn lint_uint_literal<'tcx>( |
288 | cx: &LateContext<'tcx>, | |
dfeec247 | 289 | e: &'tcx hir::Expr<'tcx>, |
48663c56 XL |
290 | lit: &hir::Lit, |
291 | t: ast::UintTy, | |
292 | ) { | |
60c5eb7d | 293 | let uint_type = t.normalize(cx.sess().target.ptr_width); |
48663c56 XL |
294 | let (min, max) = uint_ty_range(uint_type); |
295 | let lit_val: u128 = match lit.node { | |
296 | // _v is u8, within range by definition | |
297 | ast::LitKind::Byte(_v) => return, | |
298 | ast::LitKind::Int(v, _) => v, | |
299 | _ => bug!(), | |
300 | }; | |
301 | if lit_val < min || lit_val > max { | |
dc9dc135 XL |
302 | let parent_id = cx.tcx.hir().get_parent_node(e.hir_id); |
303 | if let Node::Expr(par_e) = cx.tcx.hir().get(parent_id) { | |
e74abb32 | 304 | match par_e.kind { |
48663c56 | 305 | hir::ExprKind::Cast(..) => { |
3dfed10e | 306 | if let ty::Char = cx.typeck_results().expr_ty(par_e).kind { |
74b04a01 XL |
307 | cx.struct_span_lint(OVERFLOWING_LITERALS, par_e.span, |lint| { |
308 | lint.build("only `u8` can be cast into `char`") | |
309 | .span_suggestion( | |
310 | par_e.span, | |
311 | &"use a `char` literal instead", | |
312 | format!("'\\u{{{:X}}}'", lit_val), | |
313 | Applicability::MachineApplicable, | |
314 | ) | |
315 | .emit(); | |
316 | }); | |
48663c56 XL |
317 | return; |
318 | } | |
319 | } | |
3dfed10e | 320 | hir::ExprKind::Struct(..) if is_range_literal(par_e) => { |
dfeec247 XL |
321 | let t = t.name_str(); |
322 | if lint_overflowing_range_endpoint(cx, lit, lit_val, max, e, par_e, t) { | |
323 | // The overflowing literal lint was overridden. | |
324 | return; | |
48663c56 | 325 | } |
dfeec247 | 326 | } |
48663c56 XL |
327 | _ => {} |
328 | } | |
329 | } | |
330 | if let Some(repr_str) = get_bin_hex_repr(cx, lit) { | |
331 | report_bin_hex_error(cx, e, attr::IntType::UnsignedInt(t), repr_str, lit_val, false); | |
332 | return; | |
333 | } | |
74b04a01 | 334 | cx.struct_span_lint(OVERFLOWING_LITERALS, e.span, |lint| { |
ba9703b0 XL |
335 | lint.build(&format!("literal out of range for `{}`", t.name_str())) |
336 | .note(&format!( | |
337 | "the literal `{}` does not fit into the type `{}` whose range is `{}..={}`", | |
338 | cx.sess() | |
339 | .source_map() | |
340 | .span_to_snippet(lit.span) | |
341 | .expect("must get snippet from literal"), | |
342 | t.name_str(), | |
343 | min, | |
344 | max, | |
345 | )) | |
346 | .emit() | |
74b04a01 | 347 | }); |
48663c56 XL |
348 | } |
349 | } | |
350 | ||
f035d41b XL |
351 | fn lint_literal<'tcx>( |
352 | cx: &LateContext<'tcx>, | |
48663c56 | 353 | type_limits: &TypeLimits, |
dfeec247 | 354 | e: &'tcx hir::Expr<'tcx>, |
48663c56 XL |
355 | lit: &hir::Lit, |
356 | ) { | |
3dfed10e | 357 | match cx.typeck_results().node_type(e.hir_id).kind { |
48663c56 XL |
358 | ty::Int(t) => { |
359 | match lit.node { | |
ba9703b0 | 360 | ast::LitKind::Int(v, ast::LitIntType::Signed(_) | ast::LitIntType::Unsuffixed) => { |
48663c56 XL |
361 | lint_int_literal(cx, type_limits, e, lit, t, v) |
362 | } | |
363 | _ => bug!(), | |
364 | }; | |
365 | } | |
dfeec247 | 366 | ty::Uint(t) => lint_uint_literal(cx, e, lit, t), |
48663c56 XL |
367 | ty::Float(t) => { |
368 | let is_infinite = match lit.node { | |
dfeec247 XL |
369 | ast::LitKind::Float(v, _) => match t { |
370 | ast::FloatTy::F32 => v.as_str().parse().map(f32::is_infinite), | |
371 | ast::FloatTy::F64 => v.as_str().parse().map(f64::is_infinite), | |
372 | }, | |
48663c56 XL |
373 | _ => bug!(), |
374 | }; | |
375 | if is_infinite == Ok(true) { | |
74b04a01 | 376 | cx.struct_span_lint(OVERFLOWING_LITERALS, e.span, |lint| { |
ba9703b0 XL |
377 | lint.build(&format!("literal out of range for `{}`", t.name_str())) |
378 | .note(&format!( | |
379 | "the literal `{}` does not fit into the type `{}` and will be converted to `std::{}::INFINITY`", | |
380 | cx.sess() | |
381 | .source_map() | |
382 | .span_to_snippet(lit.span) | |
383 | .expect("must get snippet from literal"), | |
384 | t.name_str(), | |
385 | t.name_str(), | |
386 | )) | |
387 | .emit(); | |
74b04a01 | 388 | }); |
48663c56 XL |
389 | } |
390 | } | |
391 | _ => {} | |
392 | } | |
393 | } | |
394 | ||
f035d41b XL |
395 | impl<'tcx> LateLintPass<'tcx> for TypeLimits { |
396 | fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx hir::Expr<'tcx>) { | |
e74abb32 | 397 | match e.kind { |
dfeec247 | 398 | hir::ExprKind::Unary(hir::UnOp::UnNeg, ref expr) => { |
b039eaaf | 399 | // propagate negation, if the negation itself isn't negated |
ba9703b0 XL |
400 | if self.negated_expr_id != Some(e.hir_id) { |
401 | self.negated_expr_id = Some(expr.hir_id); | |
b039eaaf | 402 | } |
c30ab7b3 | 403 | } |
8faf50e0 | 404 | hir::ExprKind::Binary(binop, ref l, ref r) => { |
32a655c1 | 405 | if is_comparison(binop) && !check_limits(cx, binop, &l, &r) { |
74b04a01 XL |
406 | cx.struct_span_lint(UNUSED_COMPARISONS, e.span, |lint| { |
407 | lint.build("comparison is useless due to type limits").emit() | |
408 | }); | |
b039eaaf | 409 | } |
c30ab7b3 | 410 | } |
48663c56 XL |
411 | hir::ExprKind::Lit(ref lit) => lint_literal(cx, self, e, lit), |
412 | _ => {} | |
b039eaaf SL |
413 | }; |
414 | ||
c30ab7b3 | 415 | fn is_valid<T: cmp::PartialOrd>(binop: hir::BinOp, v: T, min: T, max: T) -> bool { |
b039eaaf | 416 | match binop.node { |
8faf50e0 XL |
417 | hir::BinOpKind::Lt => v > min && v <= max, |
418 | hir::BinOpKind::Le => v >= min && v < max, | |
419 | hir::BinOpKind::Gt => v >= min && v < max, | |
420 | hir::BinOpKind::Ge => v > min && v <= max, | |
421 | hir::BinOpKind::Eq | hir::BinOpKind::Ne => v >= min && v <= max, | |
c30ab7b3 | 422 | _ => bug!(), |
b039eaaf SL |
423 | } |
424 | } | |
425 | ||
426 | fn rev_binop(binop: hir::BinOp) -> hir::BinOp { | |
dfeec247 XL |
427 | source_map::respan( |
428 | binop.span, | |
429 | match binop.node { | |
430 | hir::BinOpKind::Lt => hir::BinOpKind::Gt, | |
431 | hir::BinOpKind::Le => hir::BinOpKind::Ge, | |
432 | hir::BinOpKind::Gt => hir::BinOpKind::Lt, | |
433 | hir::BinOpKind::Ge => hir::BinOpKind::Le, | |
434 | _ => return binop, | |
435 | }, | |
436 | ) | |
b039eaaf SL |
437 | } |
438 | ||
dfeec247 | 439 | fn check_limits( |
f035d41b | 440 | cx: &LateContext<'_>, |
dfeec247 XL |
441 | binop: hir::BinOp, |
442 | l: &hir::Expr<'_>, | |
443 | r: &hir::Expr<'_>, | |
444 | ) -> bool { | |
e74abb32 | 445 | let (lit, expr, swap) = match (&l.kind, &r.kind) { |
8faf50e0 XL |
446 | (&hir::ExprKind::Lit(_), _) => (l, r, true), |
447 | (_, &hir::ExprKind::Lit(_)) => (r, l, false), | |
c30ab7b3 | 448 | _ => return true, |
b039eaaf SL |
449 | }; |
450 | // Normalize the binop so that the literal is always on the RHS in | |
451 | // the comparison | |
c30ab7b3 | 452 | let norm_binop = if swap { rev_binop(binop) } else { binop }; |
3dfed10e | 453 | match cx.typeck_results().node_type(expr.hir_id).kind { |
b7449926 | 454 | ty::Int(int_ty) => { |
b039eaaf | 455 | let (min, max) = int_ty_range(int_ty); |
e74abb32 | 456 | let lit_val: i128 = match lit.kind { |
dfeec247 | 457 | hir::ExprKind::Lit(ref li) => match li.node { |
ba9703b0 XL |
458 | ast::LitKind::Int( |
459 | v, | |
460 | ast::LitIntType::Signed(_) | ast::LitIntType::Unsuffixed, | |
461 | ) => v as i128, | |
dfeec247 | 462 | _ => return true, |
32a655c1 | 463 | }, |
dfeec247 | 464 | _ => bug!(), |
b039eaaf SL |
465 | }; |
466 | is_valid(norm_binop, lit_val, min, max) | |
467 | } | |
b7449926 | 468 | ty::Uint(uint_ty) => { |
dfeec247 | 469 | let (min, max): (u128, u128) = uint_ty_range(uint_ty); |
e74abb32 | 470 | let lit_val: u128 = match lit.kind { |
dfeec247 XL |
471 | hir::ExprKind::Lit(ref li) => match li.node { |
472 | ast::LitKind::Int(v, _) => v, | |
473 | _ => return true, | |
32a655c1 | 474 | }, |
dfeec247 | 475 | _ => bug!(), |
b039eaaf SL |
476 | }; |
477 | is_valid(norm_binop, lit_val, min, max) | |
478 | } | |
c30ab7b3 | 479 | _ => true, |
b039eaaf SL |
480 | } |
481 | } | |
482 | ||
483 | fn is_comparison(binop: hir::BinOp) -> bool { | |
484 | match binop.node { | |
dfeec247 XL |
485 | hir::BinOpKind::Eq |
486 | | hir::BinOpKind::Lt | |
487 | | hir::BinOpKind::Le | |
488 | | hir::BinOpKind::Ne | |
489 | | hir::BinOpKind::Ge | |
490 | | hir::BinOpKind::Gt => true, | |
c30ab7b3 | 491 | _ => false, |
b039eaaf SL |
492 | } |
493 | } | |
b039eaaf SL |
494 | } |
495 | } | |
496 | ||
497 | declare_lint! { | |
498 | IMPROPER_CTYPES, | |
499 | Warn, | |
500 | "proper use of libc types in foreign modules" | |
501 | } | |
502 | ||
f035d41b XL |
503 | declare_lint_pass!(ImproperCTypesDeclarations => [IMPROPER_CTYPES]); |
504 | ||
505 | declare_lint! { | |
506 | IMPROPER_CTYPES_DEFINITIONS, | |
507 | Warn, | |
508 | "proper use of libc types in foreign item definitions" | |
509 | } | |
510 | ||
511 | declare_lint_pass!(ImproperCTypesDefinitions => [IMPROPER_CTYPES_DEFINITIONS]); | |
512 | ||
3dfed10e XL |
513 | #[derive(Clone, Copy)] |
514 | crate enum CItemKind { | |
515 | Declaration, | |
516 | Definition, | |
f035d41b | 517 | } |
532ac7d7 | 518 | |
dc9dc135 | 519 | struct ImproperCTypesVisitor<'a, 'tcx> { |
f035d41b | 520 | cx: &'a LateContext<'tcx>, |
3dfed10e | 521 | mode: CItemKind, |
b039eaaf SL |
522 | } |
523 | ||
0531ce1d | 524 | enum FfiResult<'tcx> { |
b039eaaf | 525 | FfiSafe, |
0531ce1d | 526 | FfiPhantom(Ty<'tcx>), |
f035d41b | 527 | FfiUnsafe { ty: Ty<'tcx>, reason: String, help: Option<String> }, |
b039eaaf SL |
528 | } |
529 | ||
3dfed10e XL |
530 | /// Is type known to be non-null? |
531 | fn ty_is_known_nonnull<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, mode: CItemKind) -> bool { | |
532 | let tcx = cx.tcx; | |
533 | match ty.kind { | |
534 | ty::FnPtr(_) => true, | |
535 | ty::Ref(..) => true, | |
536 | ty::Adt(def, _) if def.is_box() && matches!(mode, CItemKind::Definition) => true, | |
537 | ty::Adt(def, substs) if def.repr.transparent() && !def.is_union() => { | |
538 | let guaranteed_nonnull_optimization = tcx | |
539 | .get_attrs(def.did) | |
540 | .iter() | |
541 | .any(|a| tcx.sess.check_name(a, sym::rustc_nonnull_optimization_guaranteed)); | |
542 | ||
543 | if guaranteed_nonnull_optimization { | |
544 | return true; | |
f9652781 | 545 | } |
3dfed10e XL |
546 | for variant in &def.variants { |
547 | if let Some(field) = variant.transparent_newtype_field(tcx) { | |
548 | if ty_is_known_nonnull(cx, field.ty(tcx, substs), mode) { | |
549 | return true; | |
f035d41b | 550 | } |
c30ab7b3 | 551 | } |
b039eaaf | 552 | } |
3dfed10e XL |
553 | |
554 | false | |
b039eaaf | 555 | } |
3dfed10e | 556 | _ => false, |
b039eaaf | 557 | } |
3dfed10e | 558 | } |
dc9dc135 | 559 | |
3dfed10e XL |
560 | /// Given a non-null scalar (or transparent) type `ty`, return the nullable version of that type. |
561 | /// If the type passed in was not scalar, returns None. | |
562 | fn get_nullable_type<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'tcx>> { | |
563 | let tcx = cx.tcx; | |
564 | Some(match ty.kind { | |
565 | ty::Adt(field_def, field_substs) => { | |
566 | let inner_field_ty = { | |
567 | let first_non_zst_ty = | |
568 | field_def.variants.iter().filter_map(|v| v.transparent_newtype_field(tcx)); | |
569 | debug_assert_eq!( | |
570 | first_non_zst_ty.clone().count(), | |
571 | 1, | |
572 | "Wrong number of fields for transparent type" | |
573 | ); | |
574 | first_non_zst_ty | |
575 | .last() | |
576 | .expect("No non-zst fields in transparent type.") | |
577 | .ty(tcx, field_substs) | |
578 | }; | |
579 | return get_nullable_type(cx, inner_field_ty); | |
580 | } | |
581 | ty::Int(ty) => tcx.mk_mach_int(ty), | |
582 | ty::Uint(ty) => tcx.mk_mach_uint(ty), | |
583 | ty::RawPtr(ty_mut) => tcx.mk_ptr(ty_mut), | |
584 | // As these types are always non-null, the nullable equivalent of | |
585 | // Option<T> of these types are their raw pointer counterparts. | |
586 | ty::Ref(_region, ty, mutbl) => tcx.mk_ptr(ty::TypeAndMut { ty, mutbl }), | |
587 | ty::FnPtr(..) => { | |
588 | // There is no nullable equivalent for Rust's function pointers -- you | |
589 | // must use an Option<fn(..) -> _> to represent it. | |
590 | ty | |
591 | } | |
592 | ||
593 | // We should only ever reach this case if ty_is_known_nonnull is extended | |
594 | // to other types. | |
595 | ref unhandled => { | |
596 | debug!( | |
597 | "get_nullable_type: Unhandled scalar kind: {:?} while checking {:?}", | |
598 | unhandled, ty | |
599 | ); | |
600 | return None; | |
601 | } | |
602 | }) | |
603 | } | |
604 | ||
605 | /// Check if this enum can be safely exported based on the "nullable pointer optimization". If it | |
606 | /// can, return the the type that `ty` can be safely converted to, otherwise return `None`. | |
607 | /// Currently restricted to function pointers, boxes, references, `core::num::NonZero*`, | |
608 | /// `core::ptr::NonNull`, and `#[repr(transparent)]` newtypes. | |
609 | /// FIXME: This duplicates code in codegen. | |
610 | crate fn repr_nullable_ptr<'tcx>( | |
611 | cx: &LateContext<'tcx>, | |
612 | ty: Ty<'tcx>, | |
613 | ckind: CItemKind, | |
614 | ) -> Option<Ty<'tcx>> { | |
615 | debug!("is_repr_nullable_ptr(cx, ty = {:?})", ty); | |
616 | if let ty::Adt(ty_def, substs) = ty.kind { | |
f035d41b | 617 | if ty_def.variants.len() != 2 { |
3dfed10e | 618 | return None; |
f035d41b | 619 | } |
dc9dc135 | 620 | |
f035d41b XL |
621 | let get_variant_fields = |index| &ty_def.variants[VariantIdx::new(index)].fields; |
622 | let variant_fields = [get_variant_fields(0), get_variant_fields(1)]; | |
623 | let fields = if variant_fields[0].is_empty() { | |
624 | &variant_fields[1] | |
625 | } else if variant_fields[1].is_empty() { | |
626 | &variant_fields[0] | |
627 | } else { | |
3dfed10e | 628 | return None; |
f035d41b | 629 | }; |
dc9dc135 | 630 | |
f035d41b | 631 | if fields.len() != 1 { |
3dfed10e | 632 | return None; |
f035d41b | 633 | } |
dc9dc135 | 634 | |
3dfed10e XL |
635 | let field_ty = fields[0].ty(cx.tcx, substs); |
636 | if !ty_is_known_nonnull(cx, field_ty, ckind) { | |
637 | return None; | |
f035d41b | 638 | } |
dc9dc135 | 639 | |
3dfed10e XL |
640 | // At this point, the field's type is known to be nonnull and the parent enum is Option-like. |
641 | // If the computed size for the field and the enum are different, the nonnull optimization isn't | |
642 | // being applied (and we've got a problem somewhere). | |
643 | let compute_size_skeleton = |t| SizeSkeleton::compute(t, cx.tcx, cx.param_env).unwrap(); | |
f035d41b XL |
644 | if !compute_size_skeleton(ty).same_size(compute_size_skeleton(field_ty)) { |
645 | bug!("improper_ctypes: Option nonnull optimization not applied?"); | |
646 | } | |
dc9dc135 | 647 | |
3dfed10e XL |
648 | // Return the nullable type this Option-like enum can be safely represented with. |
649 | let field_ty_abi = &cx.layout_of(field_ty).unwrap().abi; | |
650 | if let Abi::Scalar(field_ty_scalar) = field_ty_abi { | |
651 | match (field_ty_scalar.valid_range.start(), field_ty_scalar.valid_range.end()) { | |
652 | (0, _) => unreachable!("Non-null optimisation extended to a non-zero value."), | |
653 | (1, _) => { | |
654 | return Some(get_nullable_type(cx, field_ty).unwrap()); | |
655 | } | |
656 | (start, end) => unreachable!("Unhandled start and end range: ({}, {})", start, end), | |
657 | }; | |
658 | } | |
f035d41b | 659 | } |
3dfed10e XL |
660 | None |
661 | } | |
b039eaaf | 662 | |
3dfed10e | 663 | impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> { |
60c5eb7d XL |
664 | /// Check if the type is array and emit an unsafe type lint. |
665 | fn check_for_array_ty(&mut self, sp: Span, ty: Ty<'tcx>) -> bool { | |
666 | if let ty::Array(..) = ty.kind { | |
667 | self.emit_ffi_unsafe_type_lint( | |
668 | ty, | |
669 | sp, | |
670 | "passing raw arrays by value is not FFI-safe", | |
671 | Some("consider passing a pointer to the array"), | |
672 | ); | |
673 | true | |
674 | } else { | |
675 | false | |
676 | } | |
677 | } | |
678 | ||
f035d41b XL |
679 | /// Checks if the given field's type is "ffi-safe". |
680 | fn check_field_type_for_ffi( | |
681 | &self, | |
682 | cache: &mut FxHashSet<Ty<'tcx>>, | |
683 | field: &ty::FieldDef, | |
684 | substs: SubstsRef<'tcx>, | |
685 | ) -> FfiResult<'tcx> { | |
686 | let field_ty = field.ty(self.cx.tcx, substs); | |
687 | if field_ty.has_opaque_types() { | |
688 | self.check_type_for_ffi(cache, field_ty) | |
689 | } else { | |
690 | let field_ty = self.cx.tcx.normalize_erasing_regions(self.cx.param_env, field_ty); | |
691 | self.check_type_for_ffi(cache, field_ty) | |
692 | } | |
693 | } | |
694 | ||
695 | /// Checks if the given `VariantDef`'s field types are "ffi-safe". | |
696 | fn check_variant_for_ffi( | |
697 | &self, | |
698 | cache: &mut FxHashSet<Ty<'tcx>>, | |
699 | ty: Ty<'tcx>, | |
700 | def: &ty::AdtDef, | |
701 | variant: &ty::VariantDef, | |
702 | substs: SubstsRef<'tcx>, | |
703 | ) -> FfiResult<'tcx> { | |
704 | use FfiResult::*; | |
705 | ||
706 | if def.repr.transparent() { | |
707 | // Can assume that only one field is not a ZST, so only check | |
708 | // that field's type for FFI-safety. | |
709 | if let Some(field) = variant.transparent_newtype_field(self.cx.tcx) { | |
710 | self.check_field_type_for_ffi(cache, field, substs) | |
711 | } else { | |
712 | bug!("malformed transparent type"); | |
713 | } | |
714 | } else { | |
715 | // We can't completely trust repr(C) markings; make sure the fields are | |
716 | // actually safe. | |
717 | let mut all_phantom = !variant.fields.is_empty(); | |
718 | for field in &variant.fields { | |
719 | match self.check_field_type_for_ffi(cache, &field, substs) { | |
720 | FfiSafe => { | |
721 | all_phantom = false; | |
722 | } | |
723 | FfiPhantom(..) if def.is_enum() => { | |
724 | return FfiUnsafe { | |
725 | ty, | |
726 | reason: "this enum contains a PhantomData field".into(), | |
727 | help: None, | |
728 | }; | |
729 | } | |
730 | FfiPhantom(..) => {} | |
731 | r => return r, | |
732 | } | |
733 | } | |
734 | ||
735 | if all_phantom { FfiPhantom(ty) } else { FfiSafe } | |
736 | } | |
737 | } | |
738 | ||
9fa01778 | 739 | /// Checks if the given type is "ffi-safe" (has a stable, well-defined |
b039eaaf | 740 | /// representation which can be exported to C code). |
dfeec247 | 741 | fn check_type_for_ffi(&self, cache: &mut FxHashSet<Ty<'tcx>>, ty: Ty<'tcx>) -> FfiResult<'tcx> { |
9fa01778 | 742 | use FfiResult::*; |
8bb4bdeb | 743 | |
3dfed10e | 744 | let tcx = self.cx.tcx; |
b039eaaf SL |
745 | |
746 | // Protect against infinite recursion, for example | |
747 | // `struct S(*mut S);`. | |
748 | // FIXME: A recursion limit is necessary as well, for irregular | |
b7449926 | 749 | // recursive types. |
b039eaaf SL |
750 | if !cache.insert(ty) { |
751 | return FfiSafe; | |
752 | } | |
753 | ||
e74abb32 | 754 | match ty.kind { |
3dfed10e | 755 | ty::Adt(def, _) if def.is_box() && matches!(self.mode, CItemKind::Definition) => { |
f9652781 XL |
756 | FfiSafe |
757 | } | |
758 | ||
b7449926 | 759 | ty::Adt(def, substs) => { |
8bb4bdeb | 760 | if def.is_phantom_data() { |
0531ce1d | 761 | return FfiPhantom(ty); |
8bb4bdeb | 762 | } |
c30ab7b3 | 763 | match def.adt_kind() { |
f035d41b XL |
764 | AdtKind::Struct | AdtKind::Union => { |
765 | let kind = if def.is_struct() { "struct" } else { "union" }; | |
766 | ||
2c00a5a8 | 767 | if !def.repr.c() && !def.repr.transparent() { |
0531ce1d | 768 | return FfiUnsafe { |
e1599b0c | 769 | ty, |
f035d41b XL |
770 | reason: format!("this {} has unspecified layout", kind), |
771 | help: Some(format!( | |
dfeec247 | 772 | "consider adding a `#[repr(C)]` or \ |
f035d41b XL |
773 | `#[repr(transparent)]` attribute to this {}", |
774 | kind | |
775 | )), | |
0531ce1d | 776 | }; |
c30ab7b3 | 777 | } |
b039eaaf | 778 | |
e74abb32 XL |
779 | let is_non_exhaustive = |
780 | def.non_enum_variant().is_field_list_non_exhaustive(); | |
781 | if is_non_exhaustive && !def.did.is_local() { | |
782 | return FfiUnsafe { | |
783 | ty, | |
f035d41b | 784 | reason: format!("this {} is non-exhaustive", kind), |
e74abb32 XL |
785 | help: None, |
786 | }; | |
787 | } | |
788 | ||
2c00a5a8 | 789 | if def.non_enum_variant().fields.is_empty() { |
0531ce1d | 790 | return FfiUnsafe { |
e1599b0c | 791 | ty, |
f035d41b XL |
792 | reason: format!("this {} has no fields", kind), |
793 | help: Some(format!("consider adding a member to this {}", kind)), | |
0531ce1d | 794 | }; |
8bb4bdeb XL |
795 | } |
796 | ||
f035d41b | 797 | self.check_variant_for_ffi(cache, ty, def, def.non_enum_variant(), substs) |
b039eaaf | 798 | } |
c30ab7b3 SL |
799 | AdtKind::Enum => { |
800 | if def.variants.is_empty() { | |
801 | // Empty enums are okay... although sort of useless. | |
802 | return FfiSafe; | |
803 | } | |
9e0c209e | 804 | |
c30ab7b3 SL |
805 | // Check for a repr() attribute to specify the size of the |
806 | // discriminant. | |
dc9dc135 | 807 | if !def.repr.c() && !def.repr.transparent() && def.repr.int.is_none() { |
8bb4bdeb | 808 | // Special-case types like `Option<extern fn()>`. |
3dfed10e | 809 | if repr_nullable_ptr(self.cx, ty, self.mode).is_none() { |
0531ce1d | 810 | return FfiUnsafe { |
e1599b0c | 811 | ty, |
f035d41b | 812 | reason: "enum has no representation hint".into(), |
dfeec247 XL |
813 | help: Some( |
814 | "consider adding a `#[repr(C)]`, \ | |
dc9dc135 | 815 | `#[repr(transparent)]`, or integer `#[repr(...)]` \ |
f035d41b XL |
816 | attribute to this enum" |
817 | .into(), | |
dfeec247 | 818 | ), |
0531ce1d | 819 | }; |
9e0c209e | 820 | } |
8bb4bdeb | 821 | } |
c30ab7b3 | 822 | |
e74abb32 XL |
823 | if def.is_variant_list_non_exhaustive() && !def.did.is_local() { |
824 | return FfiUnsafe { | |
825 | ty, | |
f035d41b | 826 | reason: "this enum is non-exhaustive".into(), |
e74abb32 XL |
827 | help: None, |
828 | }; | |
829 | } | |
830 | ||
c30ab7b3 SL |
831 | // Check the contained variants. |
832 | for variant in &def.variants { | |
e74abb32 XL |
833 | let is_non_exhaustive = variant.is_field_list_non_exhaustive(); |
834 | if is_non_exhaustive && !variant.def_id.is_local() { | |
835 | return FfiUnsafe { | |
836 | ty, | |
f035d41b | 837 | reason: "this enum has non-exhaustive variants".into(), |
e74abb32 XL |
838 | help: None, |
839 | }; | |
840 | } | |
841 | ||
f035d41b XL |
842 | match self.check_variant_for_ffi(cache, ty, def, variant, substs) { |
843 | FfiSafe => (), | |
844 | r => return r, | |
9e0c209e | 845 | } |
b039eaaf | 846 | } |
f035d41b | 847 | |
c30ab7b3 | 848 | FfiSafe |
b039eaaf SL |
849 | } |
850 | } | |
c30ab7b3 | 851 | } |
b039eaaf | 852 | |
b7449926 | 853 | ty::Char => FfiUnsafe { |
e1599b0c | 854 | ty, |
f035d41b XL |
855 | reason: "the `char` type has no C equivalent".into(), |
856 | help: Some("consider using `u32` or `libc::wchar_t` instead".into()), | |
0531ce1d | 857 | }, |
b039eaaf | 858 | |
b7449926 | 859 | ty::Int(ast::IntTy::I128) | ty::Uint(ast::UintTy::U128) => FfiUnsafe { |
e1599b0c | 860 | ty, |
f035d41b | 861 | reason: "128-bit integers don't currently have a known stable ABI".into(), |
0531ce1d XL |
862 | help: None, |
863 | }, | |
ea8adc8c | 864 | |
b039eaaf | 865 | // Primitive types with a stable representation. |
b7449926 | 866 | ty::Bool | ty::Int(..) | ty::Uint(..) | ty::Float(..) | ty::Never => FfiSafe, |
b039eaaf | 867 | |
b7449926 | 868 | ty::Slice(_) => FfiUnsafe { |
e1599b0c | 869 | ty, |
f035d41b XL |
870 | reason: "slices have no C equivalent".into(), |
871 | help: Some("consider using a raw pointer instead".into()), | |
0531ce1d XL |
872 | }, |
873 | ||
dfeec247 | 874 | ty::Dynamic(..) => { |
f035d41b | 875 | FfiUnsafe { ty, reason: "trait objects have no C equivalent".into(), help: None } |
dfeec247 | 876 | } |
0531ce1d | 877 | |
b7449926 | 878 | ty::Str => FfiUnsafe { |
e1599b0c | 879 | ty, |
f035d41b XL |
880 | reason: "string slices have no C equivalent".into(), |
881 | help: Some("consider using `*const u8` and a length instead".into()), | |
0531ce1d XL |
882 | }, |
883 | ||
b7449926 | 884 | ty::Tuple(..) => FfiUnsafe { |
e1599b0c | 885 | ty, |
f035d41b XL |
886 | reason: "tuples have unspecified layout".into(), |
887 | help: Some("consider using a struct instead".into()), | |
0531ce1d | 888 | }, |
b039eaaf | 889 | |
f035d41b XL |
890 | ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) |
891 | if { | |
3dfed10e | 892 | matches!(self.mode, CItemKind::Definition) |
f035d41b XL |
893 | && ty.is_sized(self.cx.tcx.at(DUMMY_SP), self.cx.param_env) |
894 | } => | |
895 | { | |
896 | FfiSafe | |
897 | } | |
898 | ||
dfeec247 XL |
899 | ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) => { |
900 | self.check_type_for_ffi(cache, ty) | |
901 | } | |
b039eaaf | 902 | |
60c5eb7d | 903 | ty::Array(inner_ty, _) => self.check_type_for_ffi(cache, inner_ty), |
b039eaaf | 904 | |
b7449926 | 905 | ty::FnPtr(sig) => { |
f035d41b XL |
906 | if self.is_internal_abi(sig.abi()) { |
907 | return FfiUnsafe { | |
908 | ty, | |
909 | reason: "this function pointer has Rust-specific calling convention".into(), | |
910 | help: Some( | |
911 | "consider using an `extern fn(...) -> ...` \ | |
912 | function pointer instead" | |
913 | .into(), | |
914 | ), | |
915 | }; | |
b039eaaf SL |
916 | } |
917 | ||
3dfed10e | 918 | let sig = tcx.erase_late_bound_regions(&sig); |
b7449926 | 919 | if !sig.output().is_unit() { |
476ff2be | 920 | let r = self.check_type_for_ffi(cache, sig.output()); |
5bcae85e SL |
921 | match r { |
922 | FfiSafe => {} | |
c30ab7b3 SL |
923 | _ => { |
924 | return r; | |
925 | } | |
b039eaaf SL |
926 | } |
927 | } | |
476ff2be | 928 | for arg in sig.inputs() { |
b039eaaf SL |
929 | let r = self.check_type_for_ffi(cache, arg); |
930 | match r { | |
931 | FfiSafe => {} | |
c30ab7b3 SL |
932 | _ => { |
933 | return r; | |
934 | } | |
b039eaaf SL |
935 | } |
936 | } | |
937 | FfiSafe | |
938 | } | |
939 | ||
b7449926 XL |
940 | ty::Foreign(..) => FfiSafe, |
941 | ||
f035d41b XL |
942 | // While opaque types are checked for earlier, if a projection in a struct field |
943 | // normalizes to an opaque type, then it will reach this branch. | |
944 | ty::Opaque(..) => { | |
945 | FfiUnsafe { ty, reason: "opaque types have no C equivalent".into(), help: None } | |
946 | } | |
947 | ||
948 | // `extern "C" fn` functions can have type parameters, which may or may not be FFI-safe, | |
949 | // so they are currently ignored for the purposes of this lint. | |
3dfed10e | 950 | ty::Param(..) | ty::Projection(..) if matches!(self.mode, CItemKind::Definition) => { |
f035d41b XL |
951 | FfiSafe |
952 | } | |
953 | ||
dfeec247 | 954 | ty::Param(..) |
f035d41b | 955 | | ty::Projection(..) |
dfeec247 XL |
956 | | ty::Infer(..) |
957 | | ty::Bound(..) | |
f035d41b | 958 | | ty::Error(_) |
dfeec247 XL |
959 | | ty::Closure(..) |
960 | | ty::Generator(..) | |
961 | | ty::GeneratorWitness(..) | |
962 | | ty::Placeholder(..) | |
dfeec247 | 963 | | ty::FnDef(..) => bug!("unexpected type in foreign function: {:?}", ty), |
e1599b0c XL |
964 | } |
965 | } | |
966 | ||
967 | fn emit_ffi_unsafe_type_lint( | |
968 | &mut self, | |
969 | ty: Ty<'tcx>, | |
970 | sp: Span, | |
971 | note: &str, | |
972 | help: Option<&str>, | |
973 | ) { | |
f035d41b | 974 | let lint = match self.mode { |
3dfed10e XL |
975 | CItemKind::Declaration => IMPROPER_CTYPES, |
976 | CItemKind::Definition => IMPROPER_CTYPES_DEFINITIONS, | |
f035d41b XL |
977 | }; |
978 | ||
979 | self.cx.struct_span_lint(lint, sp, |lint| { | |
980 | let item_description = match self.mode { | |
3dfed10e XL |
981 | CItemKind::Declaration => "block", |
982 | CItemKind::Definition => "fn", | |
f035d41b XL |
983 | }; |
984 | let mut diag = lint.build(&format!( | |
985 | "`extern` {} uses type `{}`, which is not FFI-safe", | |
986 | item_description, ty | |
987 | )); | |
74b04a01 XL |
988 | diag.span_label(sp, "not FFI-safe"); |
989 | if let Some(help) = help { | |
990 | diag.help(help); | |
e1599b0c | 991 | } |
74b04a01 XL |
992 | diag.note(note); |
993 | if let ty::Adt(def, _) = ty.kind { | |
994 | if let Some(sp) = self.cx.tcx.hir().span_if_local(def.did) { | |
995 | diag.span_note(sp, "the type is defined here"); | |
996 | } | |
997 | } | |
998 | diag.emit(); | |
999 | }); | |
e1599b0c XL |
1000 | } |
1001 | ||
1002 | fn check_for_opaque_ty(&mut self, sp: Span, ty: Ty<'tcx>) -> bool { | |
f035d41b XL |
1003 | struct ProhibitOpaqueTypes<'a, 'tcx> { |
1004 | cx: &'a LateContext<'tcx>, | |
e1599b0c XL |
1005 | ty: Option<Ty<'tcx>>, |
1006 | }; | |
1007 | ||
f035d41b | 1008 | impl<'a, 'tcx> ty::fold::TypeVisitor<'tcx> for ProhibitOpaqueTypes<'a, 'tcx> { |
e1599b0c | 1009 | fn visit_ty(&mut self, ty: Ty<'tcx>) -> bool { |
f035d41b XL |
1010 | match ty.kind { |
1011 | ty::Opaque(..) => { | |
1012 | self.ty = Some(ty); | |
1013 | true | |
1014 | } | |
1015 | // Consider opaque types within projections FFI-safe if they do not normalize | |
1016 | // to more opaque types. | |
1017 | ty::Projection(..) => { | |
1018 | let ty = self.cx.tcx.normalize_erasing_regions(self.cx.param_env, ty); | |
1019 | ||
1020 | // If `ty` is a opaque type directly then `super_visit_with` won't invoke | |
1021 | // this function again. | |
1022 | if ty.has_opaque_types() { self.visit_ty(ty) } else { false } | |
1023 | } | |
1024 | _ => ty.super_visit_with(self), | |
e1599b0c XL |
1025 | } |
1026 | } | |
1027 | } | |
1028 | ||
f035d41b | 1029 | let mut visitor = ProhibitOpaqueTypes { cx: self.cx, ty: None }; |
e1599b0c XL |
1030 | ty.visit_with(&mut visitor); |
1031 | if let Some(ty) = visitor.ty { | |
dfeec247 | 1032 | self.emit_ffi_unsafe_type_lint(ty, sp, "opaque types have no C equivalent", None); |
e1599b0c XL |
1033 | true |
1034 | } else { | |
1035 | false | |
b039eaaf SL |
1036 | } |
1037 | } | |
1038 | ||
f035d41b XL |
1039 | fn check_type_for_ffi_and_report_errors( |
1040 | &mut self, | |
1041 | sp: Span, | |
1042 | ty: Ty<'tcx>, | |
1043 | is_static: bool, | |
1044 | is_return_type: bool, | |
1045 | ) { | |
e1599b0c XL |
1046 | // We have to check for opaque types before `normalize_erasing_regions`, |
1047 | // which will replace opaque types with their underlying concrete type. | |
1048 | if self.check_for_opaque_ty(sp, ty) { | |
1049 | // We've already emitted an error due to an opaque type. | |
1050 | return; | |
1051 | } | |
1052 | ||
54a0048b SL |
1053 | // it is only OK to use this function because extern fns cannot have |
1054 | // any generic types right now: | |
f035d41b XL |
1055 | let ty = self.cx.tcx.normalize_erasing_regions(self.cx.param_env, ty); |
1056 | ||
1057 | // C doesn't really support passing arrays by value - the only way to pass an array by value | |
1058 | // is through a struct. So, first test that the top level isn't an array, and then | |
1059 | // recursively check the types inside. | |
60c5eb7d XL |
1060 | if !is_static && self.check_for_array_ty(sp, ty) { |
1061 | return; | |
1062 | } | |
b039eaaf | 1063 | |
f035d41b XL |
1064 | // Don't report FFI errors for unit return types. This check exists here, and not in |
1065 | // `check_foreign_fn` (where it would make more sense) so that normalization has definitely | |
1066 | // happened. | |
1067 | if is_return_type && ty.is_unit() { | |
1068 | return; | |
1069 | } | |
1070 | ||
0bf4aa26 | 1071 | match self.check_type_for_ffi(&mut FxHashSet::default(), ty) { |
b039eaaf | 1072 | FfiResult::FfiSafe => {} |
0531ce1d | 1073 | FfiResult::FfiPhantom(ty) => { |
e1599b0c | 1074 | self.emit_ffi_unsafe_type_lint(ty, sp, "composed only of `PhantomData`", None); |
9e0c209e | 1075 | } |
f035d41b XL |
1076 | // If `ty` is a `repr(transparent)` newtype, and the non-zero-sized type is a generic |
1077 | // argument, which after substitution, is `()`, then this branch can be hit. | |
3dfed10e | 1078 | FfiResult::FfiUnsafe { ty, .. } if is_return_type && ty.is_unit() => {} |
e1599b0c | 1079 | FfiResult::FfiUnsafe { ty, reason, help } => { |
f035d41b | 1080 | self.emit_ffi_unsafe_type_lint(ty, sp, &reason, help.as_deref()); |
b039eaaf SL |
1081 | } |
1082 | } | |
1083 | } | |
b039eaaf | 1084 | |
dfeec247 | 1085 | fn check_foreign_fn(&mut self, id: hir::HirId, decl: &hir::FnDecl<'_>) { |
416331ca | 1086 | let def_id = self.cx.tcx.hir().local_def_id(id); |
041b39d2 | 1087 | let sig = self.cx.tcx.fn_sig(def_id); |
54a0048b SL |
1088 | let sig = self.cx.tcx.erase_late_bound_regions(&sig); |
1089 | ||
dfeec247 | 1090 | for (input_ty, input_hir) in sig.inputs().iter().zip(decl.inputs) { |
f035d41b | 1091 | self.check_type_for_ffi_and_report_errors(input_hir.span, input_ty, false, false); |
54a0048b SL |
1092 | } |
1093 | ||
74b04a01 | 1094 | if let hir::FnRetTy::Return(ref ret_hir) = decl.output { |
476ff2be | 1095 | let ret_ty = sig.output(); |
f035d41b | 1096 | self.check_type_for_ffi_and_report_errors(ret_hir.span, ret_ty, false, true); |
b039eaaf SL |
1097 | } |
1098 | } | |
54a0048b | 1099 | |
532ac7d7 | 1100 | fn check_foreign_static(&mut self, id: hir::HirId, span: Span) { |
416331ca | 1101 | let def_id = self.cx.tcx.hir().local_def_id(id); |
7cac9316 | 1102 | let ty = self.cx.tcx.type_of(def_id); |
f035d41b | 1103 | self.check_type_for_ffi_and_report_errors(span, ty, true, false); |
54a0048b | 1104 | } |
b039eaaf | 1105 | |
3dfed10e XL |
1106 | fn is_internal_abi(&self, abi: SpecAbi) -> bool { |
1107 | if let SpecAbi::Rust | |
1108 | | SpecAbi::RustCall | |
1109 | | SpecAbi::RustIntrinsic | |
1110 | | SpecAbi::PlatformIntrinsic = abi | |
1111 | { | |
f035d41b | 1112 | true |
e1599b0c | 1113 | } else { |
f035d41b XL |
1114 | false |
1115 | } | |
1116 | } | |
1117 | } | |
1118 | ||
1119 | impl<'tcx> LateLintPass<'tcx> for ImproperCTypesDeclarations { | |
1120 | fn check_foreign_item(&mut self, cx: &LateContext<'_>, it: &hir::ForeignItem<'_>) { | |
3dfed10e | 1121 | let mut vis = ImproperCTypesVisitor { cx, mode: CItemKind::Declaration }; |
f035d41b XL |
1122 | let abi = cx.tcx.hir().get_foreign_abi(it.hir_id); |
1123 | ||
1124 | if !vis.is_internal_abi(abi) { | |
e74abb32 | 1125 | match it.kind { |
b7449926 | 1126 | hir::ForeignItemKind::Fn(ref decl, _, _) => { |
532ac7d7 | 1127 | vis.check_foreign_fn(it.hir_id, decl); |
b7449926 XL |
1128 | } |
1129 | hir::ForeignItemKind::Static(ref ty, _) => { | |
532ac7d7 | 1130 | vis.check_foreign_static(it.hir_id, ty.span); |
b039eaaf | 1131 | } |
dfeec247 | 1132 | hir::ForeignItemKind::Type => (), |
b039eaaf | 1133 | } |
b039eaaf SL |
1134 | } |
1135 | } | |
1136 | } | |
5bcae85e | 1137 | |
f035d41b XL |
1138 | impl<'tcx> LateLintPass<'tcx> for ImproperCTypesDefinitions { |
1139 | fn check_fn( | |
1140 | &mut self, | |
1141 | cx: &LateContext<'tcx>, | |
1142 | kind: hir::intravisit::FnKind<'tcx>, | |
1143 | decl: &'tcx hir::FnDecl<'_>, | |
1144 | _: &'tcx hir::Body<'_>, | |
1145 | _: Span, | |
1146 | hir_id: hir::HirId, | |
1147 | ) { | |
1148 | use hir::intravisit::FnKind; | |
1149 | ||
1150 | let abi = match kind { | |
1151 | FnKind::ItemFn(_, _, header, ..) => header.abi, | |
1152 | FnKind::Method(_, sig, ..) => sig.header.abi, | |
1153 | _ => return, | |
1154 | }; | |
1155 | ||
3dfed10e | 1156 | let mut vis = ImproperCTypesVisitor { cx, mode: CItemKind::Definition }; |
f035d41b XL |
1157 | if !vis.is_internal_abi(abi) { |
1158 | vis.check_foreign_fn(hir_id, decl); | |
1159 | } | |
1160 | } | |
1161 | } | |
1162 | ||
532ac7d7 | 1163 | declare_lint_pass!(VariantSizeDifferences => [VARIANT_SIZE_DIFFERENCES]); |
5bcae85e | 1164 | |
f035d41b XL |
1165 | impl<'tcx> LateLintPass<'tcx> for VariantSizeDifferences { |
1166 | fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) { | |
e74abb32 | 1167 | if let hir::ItemKind::Enum(ref enum_definition, _) = it.kind { |
416331ca | 1168 | let item_def_id = cx.tcx.hir().local_def_id(it.hir_id); |
8faf50e0 XL |
1169 | let t = cx.tcx.type_of(item_def_id); |
1170 | let ty = cx.tcx.erase_regions(&t); | |
532ac7d7 XL |
1171 | let layout = match cx.layout_of(ty) { |
1172 | Ok(layout) => layout, | |
ba9703b0 XL |
1173 | Err( |
1174 | ty::layout::LayoutError::Unknown(_) | ty::layout::LayoutError::SizeOverflow(_), | |
1175 | ) => return, | |
532ac7d7 XL |
1176 | }; |
1177 | let (variants, tag) = match layout.variants { | |
ba9703b0 | 1178 | Variants::Multiple { |
f035d41b XL |
1179 | tag_encoding: TagEncoding::Direct, |
1180 | ref tag, | |
532ac7d7 | 1181 | ref variants, |
48663c56 | 1182 | .. |
f035d41b | 1183 | } => (variants, tag), |
532ac7d7 XL |
1184 | _ => return, |
1185 | }; | |
1186 | ||
f035d41b | 1187 | let tag_size = tag.value.size(&cx.tcx).bytes(); |
532ac7d7 | 1188 | |
dfeec247 XL |
1189 | debug!( |
1190 | "enum `{}` is {} bytes large with layout:\n{:#?}", | |
1191 | t, | |
1192 | layout.size.bytes(), | |
1193 | layout | |
1194 | ); | |
532ac7d7 | 1195 | |
dfeec247 XL |
1196 | let (largest, slargest, largest_index) = enum_definition |
1197 | .variants | |
532ac7d7 XL |
1198 | .iter() |
1199 | .zip(variants) | |
1200 | .map(|(variant, variant_layout)| { | |
f035d41b XL |
1201 | // Subtract the size of the enum tag. |
1202 | let bytes = variant_layout.size.bytes().saturating_sub(tag_size); | |
532ac7d7 | 1203 | |
dfeec247 | 1204 | debug!("- variant `{}` is {} bytes large", variant.ident, bytes); |
532ac7d7 XL |
1205 | bytes |
1206 | }) | |
1207 | .enumerate() | |
dfeec247 XL |
1208 | .fold((0, 0, 0), |(l, s, li), (idx, size)| { |
1209 | if size > l { | |
1210 | (size, l, idx) | |
1211 | } else if size > s { | |
1212 | (l, size, li) | |
1213 | } else { | |
1214 | (l, s, li) | |
1215 | } | |
532ac7d7 XL |
1216 | }); |
1217 | ||
1218 | // We only warn if the largest variant is at least thrice as large as | |
1219 | // the second-largest. | |
1220 | if largest > slargest * 3 && slargest > 0 { | |
74b04a01 | 1221 | cx.struct_span_lint( |
dfeec247 XL |
1222 | VARIANT_SIZE_DIFFERENCES, |
1223 | enum_definition.variants[largest_index].span, | |
74b04a01 XL |
1224 | |lint| { |
1225 | lint.build(&format!( | |
1226 | "enum variant is more than three times \ | |
532ac7d7 | 1227 | larger ({} bytes) than the next largest", |
74b04a01 XL |
1228 | largest |
1229 | )) | |
1230 | .emit() | |
1231 | }, | |
dfeec247 | 1232 | ); |
5bcae85e SL |
1233 | } |
1234 | } | |
1235 | } | |
1236 | } |