]>
Commit | Line | Data |
---|---|---|
74b04a01 | 1 | use super::{Parser, PathStyle, TokenType}; |
416331ca | 2 | |
dfeec247 | 3 | use crate::{maybe_recover_from_interpolated_ty_qpath, maybe_whole}; |
416331ca | 4 | |
74b04a01 | 5 | use rustc_ast::ptr::P; |
04454e1e | 6 | use rustc_ast::token::{self, Delimiter, Token, TokenKind}; |
3c0e092e XL |
7 | use rustc_ast::{ |
8 | self as ast, BareFnTy, FnRetTy, GenericBound, GenericBounds, GenericParam, Generics, Lifetime, | |
9 | MacCall, MutTy, Mutability, PolyTraitRef, TraitBoundModifier, TraitObjectSyntax, Ty, TyKind, | |
10 | }; | |
dfeec247 XL |
11 | use rustc_errors::{pluralize, struct_span_err, Applicability, PResult}; |
12 | use rustc_span::source_map::Span; | |
13 | use rustc_span::symbol::{kw, sym}; | |
dfeec247 | 14 | |
94222f64 | 15 | /// Any `?` or `~const` modifiers that appear at the start of a bound. |
dfeec247 XL |
16 | struct BoundModifiers { |
17 | /// `?Trait`. | |
18 | maybe: Option<Span>, | |
19 | ||
94222f64 | 20 | /// `~const Trait`. |
dfeec247 XL |
21 | maybe_const: Option<Span>, |
22 | } | |
23 | ||
24 | impl BoundModifiers { | |
25 | fn to_trait_bound_modifier(&self) -> TraitBoundModifier { | |
26 | match (self.maybe, self.maybe_const) { | |
27 | (None, None) => TraitBoundModifier::None, | |
28 | (Some(_), None) => TraitBoundModifier::Maybe, | |
29 | (None, Some(_)) => TraitBoundModifier::MaybeConst, | |
30 | (Some(_), Some(_)) => TraitBoundModifier::MaybeConstMaybe, | |
31 | } | |
32 | } | |
33 | } | |
416331ca | 34 | |
74b04a01 XL |
35 | #[derive(Copy, Clone, PartialEq)] |
36 | pub(super) enum AllowPlus { | |
37 | Yes, | |
38 | No, | |
39 | } | |
40 | ||
41 | #[derive(PartialEq)] | |
42 | pub(super) enum RecoverQPath { | |
43 | Yes, | |
44 | No, | |
45 | } | |
46 | ||
5099ac24 FG |
47 | pub(super) enum RecoverQuestionMark { |
48 | Yes, | |
49 | No, | |
50 | } | |
51 | ||
fc512014 XL |
52 | /// Signals whether parsing a type should recover `->`. |
53 | /// | |
54 | /// More specifically, when parsing a function like: | |
04454e1e | 55 | /// ```compile_fail |
fc512014 XL |
56 | /// fn foo() => u8 { 0 } |
57 | /// fn bar(): u8 { 0 } | |
58 | /// ``` | |
59 | /// The compiler will try to recover interpreting `foo() => u8` as `foo() -> u8` when calling | |
60 | /// `parse_ty` with anything except `RecoverReturnSign::No`, and it will try to recover `bar(): u8` | |
61 | /// as `bar() -> u8` when passing `RecoverReturnSign::Yes` to `parse_ty` | |
62 | #[derive(Copy, Clone, PartialEq)] | |
63 | pub(super) enum RecoverReturnSign { | |
64 | Yes, | |
65 | OnlyFatArrow, | |
66 | No, | |
67 | } | |
68 | ||
69 | impl RecoverReturnSign { | |
70 | /// [RecoverReturnSign::Yes] allows for recovering `fn foo() => u8` and `fn foo(): u8`, | |
71 | /// [RecoverReturnSign::OnlyFatArrow] allows for recovering only `fn foo() => u8` (recovering | |
72 | /// colons can cause problems when parsing where clauses), and | |
73 | /// [RecoverReturnSign::No] doesn't allow for any recovery of the return type arrow | |
74 | fn can_recover(self, token: &TokenKind) -> bool { | |
75 | match self { | |
76 | Self::Yes => matches!(token, token::FatArrow | token::Colon), | |
77 | Self::OnlyFatArrow => matches!(token, token::FatArrow), | |
78 | Self::No => false, | |
79 | } | |
80 | } | |
81 | } | |
82 | ||
74b04a01 XL |
83 | // Is `...` (`CVarArgs`) legal at this level of type parsing? |
84 | #[derive(PartialEq)] | |
85 | enum AllowCVariadic { | |
86 | Yes, | |
87 | No, | |
88 | } | |
89 | ||
416331ca XL |
90 | /// Returns `true` if `IDENT t` can start a type -- `IDENT::a::b`, `IDENT<u8, u8>`, |
91 | /// `IDENT<<u8 as Trait>::AssocTy>`. | |
92 | /// | |
93 | /// Types can also be of the form `IDENT(u8, u8) -> u8`, however this assumes | |
94 | /// that `IDENT` is not the ident of a fn trait. | |
95 | fn can_continue_type_after_non_fn_ident(t: &Token) -> bool { | |
dfeec247 | 96 | t == &token::ModSep || t == &token::Lt || t == &token::BinOp(token::Shl) |
416331ca XL |
97 | } |
98 | ||
99 | impl<'a> Parser<'a> { | |
100 | /// Parses a type. | |
101 | pub fn parse_ty(&mut self) -> PResult<'a, P<Ty>> { | |
fc512014 XL |
102 | self.parse_ty_common( |
103 | AllowPlus::Yes, | |
104 | AllowCVariadic::No, | |
105 | RecoverQPath::Yes, | |
106 | RecoverReturnSign::Yes, | |
3c0e092e | 107 | None, |
5099ac24 | 108 | RecoverQuestionMark::Yes, |
3c0e092e XL |
109 | ) |
110 | } | |
111 | ||
112 | pub(super) fn parse_ty_with_generics_recovery( | |
113 | &mut self, | |
114 | ty_params: &Generics, | |
115 | ) -> PResult<'a, P<Ty>> { | |
116 | self.parse_ty_common( | |
117 | AllowPlus::Yes, | |
118 | AllowCVariadic::No, | |
119 | RecoverQPath::Yes, | |
120 | RecoverReturnSign::Yes, | |
121 | Some(ty_params), | |
5099ac24 | 122 | RecoverQuestionMark::Yes, |
fc512014 | 123 | ) |
416331ca XL |
124 | } |
125 | ||
dfeec247 XL |
126 | /// Parse a type suitable for a function or function pointer parameter. |
127 | /// The difference from `parse_ty` is that this version allows `...` | |
1b1a35ee | 128 | /// (`CVarArgs`) at the top level of the type. |
dfeec247 | 129 | pub(super) fn parse_ty_for_param(&mut self) -> PResult<'a, P<Ty>> { |
fc512014 XL |
130 | self.parse_ty_common( |
131 | AllowPlus::Yes, | |
132 | AllowCVariadic::Yes, | |
133 | RecoverQPath::Yes, | |
134 | RecoverReturnSign::Yes, | |
3c0e092e | 135 | None, |
5099ac24 | 136 | RecoverQuestionMark::Yes, |
fc512014 | 137 | ) |
dfeec247 XL |
138 | } |
139 | ||
416331ca XL |
140 | /// Parses a type in restricted contexts where `+` is not permitted. |
141 | /// | |
142 | /// Example 1: `&'a TYPE` | |
143 | /// `+` is prohibited to maintain operator priority (P(+) < P(&)). | |
144 | /// Example 2: `value1 as TYPE + value2` | |
145 | /// `+` is prohibited to avoid interactions with expression grammar. | |
146 | pub(super) fn parse_ty_no_plus(&mut self) -> PResult<'a, P<Ty>> { | |
fc512014 XL |
147 | self.parse_ty_common( |
148 | AllowPlus::No, | |
149 | AllowCVariadic::No, | |
150 | RecoverQPath::Yes, | |
151 | RecoverReturnSign::Yes, | |
3c0e092e | 152 | None, |
5099ac24 FG |
153 | RecoverQuestionMark::Yes, |
154 | ) | |
155 | } | |
156 | ||
157 | /// Parses a type following an `as` cast. Similar to `parse_ty_no_plus`, but signaling origin | |
158 | /// for better diagnostics involving `?`. | |
159 | pub(super) fn parse_as_cast_ty(&mut self) -> PResult<'a, P<Ty>> { | |
160 | self.parse_ty_common( | |
161 | AllowPlus::No, | |
162 | AllowCVariadic::No, | |
163 | RecoverQPath::Yes, | |
164 | RecoverReturnSign::Yes, | |
165 | None, | |
166 | RecoverQuestionMark::No, | |
167 | ) | |
168 | } | |
169 | ||
170 | pub(super) fn parse_no_question_mark_recover(&mut self) -> PResult<'a, P<Ty>> { | |
171 | self.parse_ty_common( | |
172 | AllowPlus::Yes, | |
173 | AllowCVariadic::No, | |
174 | RecoverQPath::Yes, | |
175 | RecoverReturnSign::Yes, | |
176 | None, | |
177 | RecoverQuestionMark::No, | |
fc512014 XL |
178 | ) |
179 | } | |
180 | ||
181 | /// Parse a type without recovering `:` as `->` to avoid breaking code such as `where fn() : for<'a>` | |
182 | pub(super) fn parse_ty_for_where_clause(&mut self) -> PResult<'a, P<Ty>> { | |
183 | self.parse_ty_common( | |
184 | AllowPlus::Yes, | |
185 | AllowCVariadic::Yes, | |
186 | RecoverQPath::Yes, | |
187 | RecoverReturnSign::OnlyFatArrow, | |
3c0e092e | 188 | None, |
5099ac24 | 189 | RecoverQuestionMark::Yes, |
fc512014 | 190 | ) |
416331ca XL |
191 | } |
192 | ||
193 | /// Parses an optional return type `[ -> TY ]` in a function declaration. | |
dfeec247 XL |
194 | pub(super) fn parse_ret_ty( |
195 | &mut self, | |
74b04a01 XL |
196 | allow_plus: AllowPlus, |
197 | recover_qpath: RecoverQPath, | |
fc512014 | 198 | recover_return_sign: RecoverReturnSign, |
74b04a01 | 199 | ) -> PResult<'a, FnRetTy> { |
dfeec247 XL |
200 | Ok(if self.eat(&token::RArrow) { |
201 | // FIXME(Centril): Can we unconditionally `allow_plus`? | |
fc512014 XL |
202 | let ty = self.parse_ty_common( |
203 | allow_plus, | |
204 | AllowCVariadic::No, | |
205 | recover_qpath, | |
206 | recover_return_sign, | |
3c0e092e | 207 | None, |
5099ac24 | 208 | RecoverQuestionMark::Yes, |
fc512014 XL |
209 | )?; |
210 | FnRetTy::Ty(ty) | |
211 | } else if recover_return_sign.can_recover(&self.token.kind) { | |
212 | // Don't `eat` to prevent `=>` from being added as an expected token which isn't | |
213 | // actually expected and could only confuse users | |
214 | self.bump(); | |
215 | self.struct_span_err(self.prev_token.span, "return types are denoted using `->`") | |
216 | .span_suggestion_short( | |
217 | self.prev_token.span, | |
218 | "use `->` instead", | |
923072b8 | 219 | "->", |
fc512014 XL |
220 | Applicability::MachineApplicable, |
221 | ) | |
222 | .emit(); | |
223 | let ty = self.parse_ty_common( | |
224 | allow_plus, | |
225 | AllowCVariadic::No, | |
226 | recover_qpath, | |
227 | recover_return_sign, | |
3c0e092e | 228 | None, |
5099ac24 | 229 | RecoverQuestionMark::Yes, |
fc512014 | 230 | )?; |
74b04a01 | 231 | FnRetTy::Ty(ty) |
416331ca | 232 | } else { |
74b04a01 | 233 | FnRetTy::Default(self.token.span.shrink_to_lo()) |
dfeec247 | 234 | }) |
416331ca XL |
235 | } |
236 | ||
dfeec247 XL |
237 | fn parse_ty_common( |
238 | &mut self, | |
74b04a01 | 239 | allow_plus: AllowPlus, |
74b04a01 | 240 | allow_c_variadic: AllowCVariadic, |
fc512014 XL |
241 | recover_qpath: RecoverQPath, |
242 | recover_return_sign: RecoverReturnSign, | |
3c0e092e | 243 | ty_generics: Option<&Generics>, |
5099ac24 | 244 | recover_question_mark: RecoverQuestionMark, |
dfeec247 | 245 | ) -> PResult<'a, P<Ty>> { |
74b04a01 | 246 | let allow_qpath_recovery = recover_qpath == RecoverQPath::Yes; |
416331ca XL |
247 | maybe_recover_from_interpolated_ty_qpath!(self, allow_qpath_recovery); |
248 | maybe_whole!(self, NtTy, |x| x); | |
249 | ||
250 | let lo = self.token.span; | |
251 | let mut impl_dyn_multi = false; | |
04454e1e | 252 | let kind = if self.check(&token::OpenDelim(Delimiter::Parenthesis)) { |
dfeec247 | 253 | self.parse_ty_tuple_or_parens(lo, allow_plus)? |
416331ca XL |
254 | } else if self.eat(&token::Not) { |
255 | // Never type `!` | |
256 | TyKind::Never | |
257 | } else if self.eat(&token::BinOp(token::Star)) { | |
dfeec247 | 258 | self.parse_ty_ptr()? |
04454e1e | 259 | } else if self.eat(&token::OpenDelim(Delimiter::Bracket)) { |
dfeec247 | 260 | self.parse_array_or_slice_ty()? |
416331ca XL |
261 | } else if self.check(&token::BinOp(token::And)) || self.check(&token::AndAnd) { |
262 | // Reference | |
263 | self.expect_and()?; | |
264 | self.parse_borrowed_pointee()? | |
265 | } else if self.eat_keyword_noexpect(kw::Typeof) { | |
dfeec247 | 266 | self.parse_typeof_ty()? |
416331ca XL |
267 | } else if self.eat_keyword(kw::Underscore) { |
268 | // A type to be inferred `_` | |
269 | TyKind::Infer | |
6a06907d | 270 | } else if self.check_fn_front_matter(false) { |
416331ca | 271 | // Function pointer type |
fc512014 | 272 | self.parse_ty_bare_fn(lo, Vec::new(), recover_return_sign)? |
416331ca XL |
273 | } else if self.check_keyword(kw::For) { |
274 | // Function pointer type or bound list (trait object type) starting with a poly-trait. | |
275 | // `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T` | |
276 | // `for<'lt> Trait1<'lt> + Trait2 + 'a` | |
416331ca | 277 | let lifetime_defs = self.parse_late_bound_lifetime_defs()?; |
6a06907d | 278 | if self.check_fn_front_matter(false) { |
fc512014 | 279 | self.parse_ty_bare_fn(lo, lifetime_defs, recover_return_sign)? |
416331ca XL |
280 | } else { |
281 | let path = self.parse_path(PathStyle::Type)?; | |
74b04a01 | 282 | let parse_plus = allow_plus == AllowPlus::Yes && self.check_plus(); |
ba9703b0 | 283 | self.parse_remaining_bounds_path(lifetime_defs, path, lo, parse_plus)? |
416331ca XL |
284 | } |
285 | } else if self.eat_keyword(kw::Impl) { | |
dfeec247 XL |
286 | self.parse_impl_ty(&mut impl_dyn_multi)? |
287 | } else if self.is_explicit_dyn_type() { | |
288 | self.parse_dyn_ty(&mut impl_dyn_multi)? | |
416331ca XL |
289 | } else if self.eat_lt() { |
290 | // Qualified path | |
291 | let (qself, path) = self.parse_qpath(PathStyle::Type)?; | |
292 | TyKind::Path(Some(qself), path) | |
ba9703b0 | 293 | } else if self.check_path() { |
3c0e092e | 294 | self.parse_path_start_ty(lo, allow_plus, ty_generics)? |
ba9703b0 XL |
295 | } else if self.can_begin_bound() { |
296 | self.parse_bare_trait_object(lo, allow_plus)? | |
dfeec247 | 297 | } else if self.eat(&token::DotDotDot) { |
74b04a01 | 298 | if allow_c_variadic == AllowCVariadic::Yes { |
416331ca XL |
299 | TyKind::CVarArgs |
300 | } else { | |
dfeec247 XL |
301 | // FIXME(Centril): Should we just allow `...` syntactically |
302 | // anywhere in a type and use semantic restrictions instead? | |
303 | self.error_illegal_c_varadic_ty(lo); | |
304 | TyKind::Err | |
416331ca XL |
305 | } |
306 | } else { | |
dfeec247 XL |
307 | let msg = format!("expected type, found {}", super::token_descr(&self.token)); |
308 | let mut err = self.struct_span_err(self.token.span, &msg); | |
416331ca XL |
309 | err.span_label(self.token.span, "expected type"); |
310 | self.maybe_annotate_with_ascription(&mut err, true); | |
311 | return Err(err); | |
312 | }; | |
313 | ||
74b04a01 | 314 | let span = lo.to(self.prev_token.span); |
923072b8 | 315 | let mut ty = self.mk_ty(span, kind); |
416331ca XL |
316 | |
317 | // Try to recover from use of `+` with incorrect priority. | |
923072b8 FG |
318 | if matches!(allow_plus, AllowPlus::Yes) { |
319 | self.maybe_recover_from_bad_type_plus(&ty)?; | |
320 | } else { | |
321 | self.maybe_report_ambiguous_plus(impl_dyn_multi, &ty); | |
322 | } | |
323 | if let RecoverQuestionMark::Yes = recover_question_mark { | |
324 | ty = self.maybe_recover_from_question_mark(ty); | |
325 | } | |
326 | if allow_qpath_recovery { self.maybe_recover_from_bad_qpath(ty) } else { Ok(ty) } | |
416331ca XL |
327 | } |
328 | ||
dfeec247 XL |
329 | /// Parses either: |
330 | /// - `(TYPE)`, a parenthesized type. | |
331 | /// - `(TYPE,)`, a tuple with a single field of type TYPE. | |
74b04a01 | 332 | fn parse_ty_tuple_or_parens(&mut self, lo: Span, allow_plus: AllowPlus) -> PResult<'a, TyKind> { |
dfeec247 XL |
333 | let mut trailing_plus = false; |
334 | let (ts, trailing) = self.parse_paren_comma_seq(|p| { | |
335 | let ty = p.parse_ty()?; | |
74b04a01 | 336 | trailing_plus = p.prev_token.kind == TokenKind::BinOp(token::Plus); |
dfeec247 XL |
337 | Ok(ty) |
338 | })?; | |
339 | ||
340 | if ts.len() == 1 && !trailing { | |
74b04a01 XL |
341 | let ty = ts.into_iter().next().unwrap().into_inner(); |
342 | let maybe_bounds = allow_plus == AllowPlus::Yes && self.token.is_like_plus(); | |
dfeec247 XL |
343 | match ty.kind { |
344 | // `(TY_BOUND_NOPAREN) + BOUND + ...`. | |
345 | TyKind::Path(None, path) if maybe_bounds => { | |
ba9703b0 | 346 | self.parse_remaining_bounds_path(Vec::new(), path, lo, true) |
dfeec247 | 347 | } |
ba9703b0 | 348 | TyKind::TraitObject(bounds, TraitObjectSyntax::None) |
dfeec247 XL |
349 | if maybe_bounds && bounds.len() == 1 && !trailing_plus => |
350 | { | |
ba9703b0 | 351 | self.parse_remaining_bounds(bounds, true) |
dfeec247 XL |
352 | } |
353 | // `(TYPE)` | |
354 | _ => Ok(TyKind::Paren(P(ty))), | |
355 | } | |
356 | } else { | |
357 | Ok(TyKind::Tup(ts)) | |
358 | } | |
359 | } | |
360 | ||
ba9703b0 XL |
361 | fn parse_bare_trait_object(&mut self, lo: Span, allow_plus: AllowPlus) -> PResult<'a, TyKind> { |
362 | let lt_no_plus = self.check_lifetime() && !self.look_ahead(1, |t| t.is_like_plus()); | |
363 | let bounds = self.parse_generic_bounds_common(allow_plus, None)?; | |
364 | if lt_no_plus { | |
5e7ed085 FG |
365 | self.struct_span_err(lo, "lifetime in trait object type must be followed by `+`") |
366 | .emit(); | |
ba9703b0 XL |
367 | } |
368 | Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::None)) | |
369 | } | |
370 | ||
371 | fn parse_remaining_bounds_path( | |
dfeec247 XL |
372 | &mut self, |
373 | generic_params: Vec<GenericParam>, | |
374 | path: ast::Path, | |
375 | lo: Span, | |
376 | parse_plus: bool, | |
377 | ) -> PResult<'a, TyKind> { | |
74b04a01 | 378 | let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_token.span)); |
ba9703b0 XL |
379 | let bounds = vec![GenericBound::Trait(poly_trait_ref, TraitBoundModifier::None)]; |
380 | self.parse_remaining_bounds(bounds, parse_plus) | |
381 | } | |
382 | ||
383 | /// Parse the remainder of a bare trait object type given an already parsed list. | |
384 | fn parse_remaining_bounds( | |
385 | &mut self, | |
386 | mut bounds: GenericBounds, | |
387 | plus: bool, | |
388 | ) -> PResult<'a, TyKind> { | |
ba9703b0 | 389 | if plus { |
416331ca | 390 | self.eat_plus(); // `+`, or `+=` gets split and `+` is discarded |
74b04a01 | 391 | bounds.append(&mut self.parse_generic_bounds(Some(self.prev_token.span))?); |
416331ca XL |
392 | } |
393 | Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::None)) | |
394 | } | |
395 | ||
dfeec247 XL |
396 | /// Parses a raw pointer type: `*[const | mut] $type`. |
397 | fn parse_ty_ptr(&mut self) -> PResult<'a, TyKind> { | |
e74abb32 | 398 | let mutbl = self.parse_const_or_mut().unwrap_or_else(|| { |
74b04a01 | 399 | let span = self.prev_token.span; |
416331ca XL |
400 | let msg = "expected mut or const in raw pointer type"; |
401 | self.struct_span_err(span, msg) | |
402 | .span_label(span, msg) | |
403 | .help("use `*mut T` or `*const T` as appropriate") | |
404 | .emit(); | |
dfeec247 | 405 | Mutability::Not |
e74abb32 | 406 | }); |
dfeec247 XL |
407 | let ty = self.parse_ty_no_plus()?; |
408 | Ok(TyKind::Ptr(MutTy { ty, mutbl })) | |
416331ca XL |
409 | } |
410 | ||
dfeec247 XL |
411 | /// Parses an array (`[TYPE; EXPR]`) or slice (`[TYPE]`) type. |
412 | /// The opening `[` bracket is already eaten. | |
413 | fn parse_array_or_slice_ty(&mut self) -> PResult<'a, TyKind> { | |
29967ef6 XL |
414 | let elt_ty = match self.parse_ty() { |
415 | Ok(ty) => ty, | |
416 | Err(mut err) | |
04454e1e | 417 | if self.look_ahead(1, |t| t.kind == token::CloseDelim(Delimiter::Bracket)) |
29967ef6 XL |
418 | | self.look_ahead(1, |t| t.kind == token::Semi) => |
419 | { | |
420 | // Recover from `[LIT; EXPR]` and `[LIT]` | |
421 | self.bump(); | |
422 | err.emit(); | |
423 | self.mk_ty(self.prev_token.span, TyKind::Err) | |
424 | } | |
425 | Err(err) => return Err(err), | |
426 | }; | |
6a06907d | 427 | |
dfeec247 | 428 | let ty = if self.eat(&token::Semi) { |
6a06907d | 429 | let mut length = self.parse_anon_const_expr()?; |
04454e1e | 430 | if let Err(e) = self.expect(&token::CloseDelim(Delimiter::Bracket)) { |
6a06907d XL |
431 | // Try to recover from `X<Y, ...>` when `X::<Y, ...>` works |
432 | self.check_mistyped_turbofish_with_multiple_type_params(e, &mut length.value)?; | |
04454e1e | 433 | self.expect(&token::CloseDelim(Delimiter::Bracket))?; |
6a06907d XL |
434 | } |
435 | TyKind::Array(elt_ty, length) | |
416331ca | 436 | } else { |
04454e1e | 437 | self.expect(&token::CloseDelim(Delimiter::Bracket))?; |
dfeec247 XL |
438 | TyKind::Slice(elt_ty) |
439 | }; | |
6a06907d | 440 | |
dfeec247 | 441 | Ok(ty) |
416331ca XL |
442 | } |
443 | ||
444 | fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> { | |
1b1a35ee XL |
445 | let and_span = self.prev_token.span; |
446 | let mut opt_lifetime = | |
447 | if self.check_lifetime() { Some(self.expect_lifetime()) } else { None }; | |
136023e0 | 448 | let mut mutbl = self.parse_mutability(); |
1b1a35ee XL |
449 | if self.token.is_lifetime() && mutbl == Mutability::Mut && opt_lifetime.is_none() { |
450 | // A lifetime is invalid here: it would be part of a bare trait bound, which requires | |
451 | // it to be followed by a plus, but we disallow plus in the pointee type. | |
452 | // So we can handle this case as an error here, and suggest `'a mut`. | |
453 | // If there *is* a plus next though, handling the error later provides better suggestions | |
454 | // (like adding parentheses) | |
455 | if !self.look_ahead(1, |t| t.is_like_plus()) { | |
456 | let lifetime_span = self.token.span; | |
457 | let span = and_span.to(lifetime_span); | |
458 | ||
459 | let mut err = self.struct_span_err(span, "lifetime must precede `mut`"); | |
460 | if let Ok(lifetime_src) = self.span_to_snippet(lifetime_span) { | |
461 | err.span_suggestion( | |
462 | span, | |
463 | "place the lifetime before `mut`", | |
464 | format!("&{} mut", lifetime_src), | |
465 | Applicability::MaybeIncorrect, | |
466 | ); | |
467 | } | |
468 | err.emit(); | |
469 | ||
470 | opt_lifetime = Some(self.expect_lifetime()); | |
471 | } | |
136023e0 XL |
472 | } else if self.token.is_keyword(kw::Dyn) |
473 | && mutbl == Mutability::Not | |
474 | && self.look_ahead(1, |t| t.is_keyword(kw::Mut)) | |
475 | { | |
476 | // We have `&dyn mut ...`, which is invalid and should be `&mut dyn ...`. | |
477 | let span = and_span.to(self.look_ahead(1, |t| t.span)); | |
478 | let mut err = self.struct_span_err(span, "`mut` must precede `dyn`"); | |
479 | err.span_suggestion( | |
480 | span, | |
481 | "place `mut` before `dyn`", | |
923072b8 | 482 | "&mut dyn", |
136023e0 XL |
483 | Applicability::MachineApplicable, |
484 | ); | |
485 | err.emit(); | |
486 | ||
487 | // Recovery | |
488 | mutbl = Mutability::Mut; | |
489 | let (dyn_tok, dyn_tok_sp) = (self.token.clone(), self.token_spacing); | |
490 | self.bump(); | |
491 | self.bump_with((dyn_tok, dyn_tok_sp)); | |
1b1a35ee | 492 | } |
416331ca | 493 | let ty = self.parse_ty_no_plus()?; |
dfeec247 XL |
494 | Ok(TyKind::Rptr(opt_lifetime, MutTy { ty, mutbl })) |
495 | } | |
496 | ||
497 | // Parses the `typeof(EXPR)`. | |
3c0e092e | 498 | // To avoid ambiguity, the type is surrounded by parentheses. |
dfeec247 | 499 | fn parse_typeof_ty(&mut self) -> PResult<'a, TyKind> { |
04454e1e | 500 | self.expect(&token::OpenDelim(Delimiter::Parenthesis))?; |
dfeec247 | 501 | let expr = self.parse_anon_const_expr()?; |
04454e1e | 502 | self.expect(&token::CloseDelim(Delimiter::Parenthesis))?; |
dfeec247 | 503 | Ok(TyKind::Typeof(expr)) |
416331ca XL |
504 | } |
505 | ||
dfeec247 | 506 | /// Parses a function pointer type (`TyKind::BareFn`). |
04454e1e FG |
507 | /// ```ignore (illustrative) |
508 | /// [unsafe] [extern "ABI"] fn (S) -> T | |
509 | /// // ^~~~~^ ^~~~^ ^~^ ^ | |
510 | /// // | | | | | |
511 | /// // | | | Return type | |
512 | /// // Function Style ABI Parameter types | |
dfeec247 | 513 | /// ``` |
ba9703b0 | 514 | /// We actually parse `FnHeader FnDecl`, but we error on `const` and `async` qualifiers. |
fc512014 XL |
515 | fn parse_ty_bare_fn( |
516 | &mut self, | |
517 | lo: Span, | |
518 | params: Vec<GenericParam>, | |
519 | recover_return_sign: RecoverReturnSign, | |
520 | ) -> PResult<'a, TyKind> { | |
a2a8927a XL |
521 | let inherited_vis = rustc_ast::Visibility { |
522 | span: rustc_span::DUMMY_SP, | |
523 | kind: rustc_ast::VisibilityKind::Inherited, | |
524 | tokens: None, | |
525 | }; | |
923072b8 | 526 | let span_start = self.token.span; |
a2a8927a XL |
527 | let ast::FnHeader { ext, unsafety, constness, asyncness } = |
528 | self.parse_fn_front_matter(&inherited_vis)?; | |
fc512014 | 529 | let decl = self.parse_fn_decl(|_| false, AllowPlus::No, recover_return_sign)?; |
ba9703b0 XL |
530 | let whole_span = lo.to(self.prev_token.span); |
531 | if let ast::Const::Yes(span) = constness { | |
04454e1e FG |
532 | // If we ever start to allow `const fn()`, then update |
533 | // feature gating for `#![feature(const_extern_fn)]` to | |
534 | // cover it. | |
ba9703b0 XL |
535 | self.error_fn_ptr_bad_qualifier(whole_span, span, "const"); |
536 | } | |
537 | if let ast::Async::Yes { span, .. } = asyncness { | |
538 | self.error_fn_ptr_bad_qualifier(whole_span, span, "async"); | |
539 | } | |
923072b8 FG |
540 | let decl_span = span_start.to(self.token.span); |
541 | Ok(TyKind::BareFn(P(BareFnTy { ext, unsafety, generic_params: params, decl, decl_span }))) | |
ba9703b0 XL |
542 | } |
543 | ||
544 | /// Emit an error for the given bad function pointer qualifier. | |
545 | fn error_fn_ptr_bad_qualifier(&self, span: Span, qual_span: Span, qual: &str) { | |
546 | self.struct_span_err(span, &format!("an `fn` pointer type cannot be `{}`", qual)) | |
547 | .span_label(qual_span, format!("`{}` because of this", qual)) | |
548 | .span_suggestion_short( | |
549 | qual_span, | |
550 | &format!("remove the `{}` qualifier", qual), | |
923072b8 | 551 | "", |
ba9703b0 XL |
552 | Applicability::MaybeIncorrect, |
553 | ) | |
554 | .emit(); | |
dfeec247 XL |
555 | } |
556 | ||
557 | /// Parses an `impl B0 + ... + Bn` type. | |
558 | fn parse_impl_ty(&mut self, impl_dyn_multi: &mut bool) -> PResult<'a, TyKind> { | |
559 | // Always parse bounds greedily for better error recovery. | |
560 | let bounds = self.parse_generic_bounds(None)?; | |
74b04a01 | 561 | *impl_dyn_multi = bounds.len() > 1 || self.prev_token.kind == TokenKind::BinOp(token::Plus); |
dfeec247 XL |
562 | Ok(TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds)) |
563 | } | |
564 | ||
565 | /// Is a `dyn B0 + ... + Bn` type allowed here? | |
566 | fn is_explicit_dyn_type(&mut self) -> bool { | |
567 | self.check_keyword(kw::Dyn) | |
17df50a5 | 568 | && (!self.token.uninterpolated_span().rust_2015() |
dfeec247 XL |
569 | || self.look_ahead(1, |t| { |
570 | t.can_begin_bound() && !can_continue_type_after_non_fn_ident(t) | |
571 | })) | |
572 | } | |
573 | ||
574 | /// Parses a `dyn B0 + ... + Bn` type. | |
575 | /// | |
576 | /// Note that this does *not* parse bare trait objects. | |
577 | fn parse_dyn_ty(&mut self, impl_dyn_multi: &mut bool) -> PResult<'a, TyKind> { | |
578 | self.bump(); // `dyn` | |
579 | // Always parse bounds greedily for better error recovery. | |
580 | let bounds = self.parse_generic_bounds(None)?; | |
74b04a01 | 581 | *impl_dyn_multi = bounds.len() > 1 || self.prev_token.kind == TokenKind::BinOp(token::Plus); |
dfeec247 | 582 | Ok(TyKind::TraitObject(bounds, TraitObjectSyntax::Dyn)) |
416331ca XL |
583 | } |
584 | ||
dfeec247 XL |
585 | /// Parses a type starting with a path. |
586 | /// | |
587 | /// This can be: | |
588 | /// 1. a type macro, `mac!(...)`, | |
589 | /// 2. a bare trait object, `B0 + ... + Bn`, | |
590 | /// 3. or a path, `path::to::MyType`. | |
3c0e092e XL |
591 | fn parse_path_start_ty( |
592 | &mut self, | |
593 | lo: Span, | |
594 | allow_plus: AllowPlus, | |
595 | ty_generics: Option<&Generics>, | |
596 | ) -> PResult<'a, TyKind> { | |
dfeec247 | 597 | // Simple path |
3c0e092e | 598 | let path = self.parse_path_inner(PathStyle::Type, ty_generics)?; |
dfeec247 XL |
599 | if self.eat(&token::Not) { |
600 | // Macro invocation in type position | |
ba9703b0 | 601 | Ok(TyKind::MacCall(MacCall { |
dfeec247 XL |
602 | path, |
603 | args: self.parse_mac_args()?, | |
604 | prior_type_ascription: self.last_type_ascription, | |
605 | })) | |
74b04a01 | 606 | } else if allow_plus == AllowPlus::Yes && self.check_plus() { |
dfeec247 | 607 | // `Trait1 + Trait2 + 'a` |
ba9703b0 | 608 | self.parse_remaining_bounds_path(Vec::new(), path, lo, true) |
dfeec247 XL |
609 | } else { |
610 | // Just a type path. | |
611 | Ok(TyKind::Path(None, path)) | |
612 | } | |
613 | } | |
614 | ||
615 | fn error_illegal_c_varadic_ty(&self, lo: Span) { | |
616 | struct_span_err!( | |
617 | self.sess.span_diagnostic, | |
74b04a01 | 618 | lo.to(self.prev_token.span), |
dfeec247 XL |
619 | E0743, |
620 | "C-variadic type `...` may not be nested inside another type", | |
621 | ) | |
622 | .emit(); | |
623 | } | |
624 | ||
625 | pub(super) fn parse_generic_bounds( | |
626 | &mut self, | |
627 | colon_span: Option<Span>, | |
628 | ) -> PResult<'a, GenericBounds> { | |
74b04a01 | 629 | self.parse_generic_bounds_common(AllowPlus::Yes, colon_span) |
416331ca XL |
630 | } |
631 | ||
632 | /// Parses bounds of a type parameter `BOUND + BOUND + ...`, possibly with trailing `+`. | |
633 | /// | |
dfeec247 XL |
634 | /// See `parse_generic_bound` for the `BOUND` grammar. |
635 | fn parse_generic_bounds_common( | |
636 | &mut self, | |
74b04a01 | 637 | allow_plus: AllowPlus, |
dfeec247 XL |
638 | colon_span: Option<Span>, |
639 | ) -> PResult<'a, GenericBounds> { | |
416331ca XL |
640 | let mut bounds = Vec::new(); |
641 | let mut negative_bounds = Vec::new(); | |
17df50a5 XL |
642 | |
643 | while self.can_begin_bound() || self.token.is_keyword(kw::Dyn) { | |
644 | if self.token.is_keyword(kw::Dyn) { | |
645 | // Account for `&dyn Trait + dyn Other`. | |
646 | self.struct_span_err(self.token.span, "invalid `dyn` keyword") | |
647 | .help("`dyn` is only needed at the start of a trait `+`-separated list") | |
648 | .span_suggestion( | |
649 | self.token.span, | |
650 | "remove this keyword", | |
923072b8 | 651 | "", |
17df50a5 XL |
652 | Applicability::MachineApplicable, |
653 | ) | |
654 | .emit(); | |
655 | self.bump(); | |
656 | } | |
dfeec247 XL |
657 | match self.parse_generic_bound()? { |
658 | Ok(bound) => bounds.push(bound), | |
659 | Err(neg_sp) => negative_bounds.push(neg_sp), | |
416331ca | 660 | } |
74b04a01 | 661 | if allow_plus == AllowPlus::No || !self.eat_plus() { |
dfeec247 | 662 | break; |
416331ca XL |
663 | } |
664 | } | |
665 | ||
dfeec247 XL |
666 | if !negative_bounds.is_empty() { |
667 | self.error_negative_bounds(colon_span, &bounds, negative_bounds); | |
668 | } | |
669 | ||
670 | Ok(bounds) | |
671 | } | |
672 | ||
673 | /// Can the current token begin a bound? | |
674 | fn can_begin_bound(&mut self) -> bool { | |
675 | // This needs to be synchronized with `TokenKind::can_begin_bound`. | |
676 | self.check_path() | |
677 | || self.check_lifetime() | |
678 | || self.check(&token::Not) // Used for error reporting only. | |
679 | || self.check(&token::Question) | |
94222f64 | 680 | || self.check(&token::Tilde) |
dfeec247 | 681 | || self.check_keyword(kw::For) |
04454e1e | 682 | || self.check(&token::OpenDelim(Delimiter::Parenthesis)) |
dfeec247 XL |
683 | } |
684 | ||
685 | fn error_negative_bounds( | |
686 | &self, | |
687 | colon_span: Option<Span>, | |
688 | bounds: &[GenericBound], | |
689 | negative_bounds: Vec<Span>, | |
690 | ) { | |
691 | let negative_bounds_len = negative_bounds.len(); | |
692 | let last_span = *negative_bounds.last().expect("no negative bounds, but still error?"); | |
693 | let mut err = self.struct_span_err(negative_bounds, "negative bounds are not supported"); | |
694 | err.span_label(last_span, "negative bounds are not supported"); | |
695 | if let Some(bound_list) = colon_span { | |
74b04a01 | 696 | let bound_list = bound_list.to(self.prev_token.span); |
dfeec247 XL |
697 | let mut new_bound_list = String::new(); |
698 | if !bounds.is_empty() { | |
699 | let mut snippets = bounds.iter().map(|bound| self.span_to_snippet(bound.span())); | |
700 | while let Some(Ok(snippet)) = snippets.next() { | |
701 | new_bound_list.push_str(" + "); | |
702 | new_bound_list.push_str(&snippet); | |
416331ca | 703 | } |
dfeec247 | 704 | new_bound_list = new_bound_list.replacen(" +", ":", 1); |
416331ca | 705 | } |
dfeec247 XL |
706 | err.tool_only_span_suggestion( |
707 | bound_list, | |
708 | &format!("remove the bound{}", pluralize!(negative_bounds_len)), | |
709 | new_bound_list, | |
710 | Applicability::MachineApplicable, | |
711 | ); | |
712 | } | |
713 | err.emit(); | |
714 | } | |
715 | ||
716 | /// Parses a bound according to the grammar: | |
04454e1e | 717 | /// ```ebnf |
dfeec247 XL |
718 | /// BOUND = TY_BOUND | LT_BOUND |
719 | /// ``` | |
720 | fn parse_generic_bound(&mut self) -> PResult<'a, Result<GenericBound, Span>> { | |
74b04a01 | 721 | let anchor_lo = self.prev_token.span; |
dfeec247 | 722 | let lo = self.token.span; |
04454e1e | 723 | let has_parens = self.eat(&token::OpenDelim(Delimiter::Parenthesis)); |
dfeec247 XL |
724 | let inner_lo = self.token.span; |
725 | let is_negative = self.eat(&token::Not); | |
726 | ||
94222f64 | 727 | let modifiers = self.parse_ty_bound_modifiers()?; |
dfeec247 XL |
728 | let bound = if self.token.is_lifetime() { |
729 | self.error_lt_bound_with_modifiers(modifiers); | |
730 | self.parse_generic_lt_bound(lo, inner_lo, has_parens)? | |
731 | } else { | |
732 | self.parse_generic_ty_bound(lo, has_parens, modifiers)? | |
733 | }; | |
734 | ||
74b04a01 | 735 | Ok(if is_negative { Err(anchor_lo.to(self.prev_token.span)) } else { Ok(bound) }) |
dfeec247 XL |
736 | } |
737 | ||
738 | /// Parses a lifetime ("outlives") bound, e.g. `'a`, according to: | |
04454e1e | 739 | /// ```ebnf |
dfeec247 XL |
740 | /// LT_BOUND = LIFETIME |
741 | /// ``` | |
742 | fn parse_generic_lt_bound( | |
743 | &mut self, | |
744 | lo: Span, | |
745 | inner_lo: Span, | |
746 | has_parens: bool, | |
747 | ) -> PResult<'a, GenericBound> { | |
748 | let bound = GenericBound::Outlives(self.expect_lifetime()); | |
749 | if has_parens { | |
750 | // FIXME(Centril): Consider not erroring here and accepting `('lt)` instead, | |
751 | // possibly introducing `GenericBound::Paren(P<GenericBound>)`? | |
752 | self.recover_paren_lifetime(lo, inner_lo)?; | |
753 | } | |
754 | Ok(bound) | |
755 | } | |
756 | ||
757 | /// Emits an error if any trait bound modifiers were present. | |
758 | fn error_lt_bound_with_modifiers(&self, modifiers: BoundModifiers) { | |
759 | if let Some(span) = modifiers.maybe_const { | |
760 | self.struct_span_err( | |
761 | span, | |
94222f64 | 762 | "`~const` may only modify trait bounds, not lifetime bounds", |
dfeec247 XL |
763 | ) |
764 | .emit(); | |
765 | } | |
766 | ||
767 | if let Some(span) = modifiers.maybe { | |
768 | self.struct_span_err(span, "`?` may only modify trait bounds, not lifetime bounds") | |
769 | .emit(); | |
770 | } | |
771 | } | |
772 | ||
773 | /// Recover on `('lifetime)` with `(` already eaten. | |
774 | fn recover_paren_lifetime(&mut self, lo: Span, inner_lo: Span) -> PResult<'a, ()> { | |
74b04a01 | 775 | let inner_span = inner_lo.to(self.prev_token.span); |
04454e1e | 776 | self.expect(&token::CloseDelim(Delimiter::Parenthesis))?; |
dfeec247 | 777 | let mut err = self.struct_span_err( |
74b04a01 | 778 | lo.to(self.prev_token.span), |
dfeec247 XL |
779 | "parenthesized lifetime bounds are not supported", |
780 | ); | |
781 | if let Ok(snippet) = self.span_to_snippet(inner_span) { | |
782 | err.span_suggestion_short( | |
74b04a01 | 783 | lo.to(self.prev_token.span), |
dfeec247 XL |
784 | "remove the parentheses", |
785 | snippet, | |
786 | Applicability::MachineApplicable, | |
787 | ); | |
788 | } | |
789 | err.emit(); | |
790 | Ok(()) | |
791 | } | |
792 | ||
94222f64 | 793 | /// Parses the modifiers that may precede a trait in a bound, e.g. `?Trait` or `~const Trait`. |
dfeec247 XL |
794 | /// |
795 | /// If no modifiers are present, this does not consume any tokens. | |
796 | /// | |
04454e1e | 797 | /// ```ebnf |
94222f64 | 798 | /// TY_BOUND_MODIFIERS = ["~const"] ["?"] |
dfeec247 | 799 | /// ``` |
94222f64 XL |
800 | fn parse_ty_bound_modifiers(&mut self) -> PResult<'a, BoundModifiers> { |
801 | let maybe_const = if self.eat(&token::Tilde) { | |
802 | let tilde = self.prev_token.span; | |
803 | self.expect_keyword(kw::Const)?; | |
804 | let span = tilde.to(self.prev_token.span); | |
805 | self.sess.gated_spans.gate(sym::const_trait_impl, span); | |
806 | Some(span) | |
807 | } else { | |
808 | None | |
809 | }; | |
dfeec247 | 810 | |
94222f64 | 811 | let maybe = if self.eat(&token::Question) { Some(self.prev_token.span) } else { None }; |
dfeec247 | 812 | |
94222f64 | 813 | Ok(BoundModifiers { maybe, maybe_const }) |
dfeec247 XL |
814 | } |
815 | ||
816 | /// Parses a type bound according to: | |
04454e1e | 817 | /// ```ebnf |
dfeec247 XL |
818 | /// TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN) |
819 | /// TY_BOUND_NOPAREN = [TY_BOUND_MODIFIERS] [for<LT_PARAM_DEFS>] SIMPLE_PATH | |
820 | /// ``` | |
821 | /// | |
94222f64 | 822 | /// For example, this grammar accepts `~const ?for<'a: 'b> m::Trait<'a>`. |
dfeec247 XL |
823 | fn parse_generic_ty_bound( |
824 | &mut self, | |
825 | lo: Span, | |
826 | has_parens: bool, | |
827 | modifiers: BoundModifiers, | |
828 | ) -> PResult<'a, GenericBound> { | |
829 | let lifetime_defs = self.parse_late_bound_lifetime_defs()?; | |
830 | let path = self.parse_path(PathStyle::Type)?; | |
831 | if has_parens { | |
17df50a5 XL |
832 | if self.token.is_like_plus() { |
833 | // Someone has written something like `&dyn (Trait + Other)`. The correct code | |
834 | // would be `&(dyn Trait + Other)`, but we don't have access to the appropriate | |
835 | // span to suggest that. When written as `&dyn Trait + Other`, an appropriate | |
836 | // suggestion is given. | |
837 | let bounds = vec![]; | |
838 | self.parse_remaining_bounds(bounds, true)?; | |
04454e1e | 839 | self.expect(&token::CloseDelim(Delimiter::Parenthesis))?; |
17df50a5 XL |
840 | let sp = vec![lo, self.prev_token.span]; |
841 | let sugg: Vec<_> = sp.iter().map(|sp| (*sp, String::new())).collect(); | |
842 | self.struct_span_err(sp, "incorrect braces around trait bounds") | |
843 | .multipart_suggestion( | |
844 | "remove the parentheses", | |
845 | sugg, | |
846 | Applicability::MachineApplicable, | |
847 | ) | |
848 | .emit(); | |
849 | } else { | |
04454e1e | 850 | self.expect(&token::CloseDelim(Delimiter::Parenthesis))?; |
17df50a5 | 851 | } |
416331ca XL |
852 | } |
853 | ||
dfeec247 | 854 | let modifier = modifiers.to_trait_bound_modifier(); |
74b04a01 | 855 | let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_token.span)); |
dfeec247 | 856 | Ok(GenericBound::Trait(poly_trait, modifier)) |
416331ca XL |
857 | } |
858 | ||
dfeec247 | 859 | /// Optionally parses `for<$generic_params>`. |
416331ca XL |
860 | pub(super) fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, Vec<GenericParam>> { |
861 | if self.eat_keyword(kw::For) { | |
862 | self.expect_lt()?; | |
863 | let params = self.parse_generic_params()?; | |
864 | self.expect_gt()?; | |
865 | // We rely on AST validation to rule out invalid cases: There must not be type | |
866 | // parameters, and the lifetime parameters must not have bounds. | |
867 | Ok(params) | |
868 | } else { | |
869 | Ok(Vec::new()) | |
870 | } | |
871 | } | |
872 | ||
3dfed10e | 873 | pub(super) fn check_lifetime(&mut self) -> bool { |
416331ca XL |
874 | self.expected_tokens.push(TokenType::Lifetime); |
875 | self.token.is_lifetime() | |
876 | } | |
877 | ||
878 | /// Parses a single lifetime `'a` or panics. | |
3dfed10e | 879 | pub(super) fn expect_lifetime(&mut self) -> Lifetime { |
416331ca | 880 | if let Some(ident) = self.token.lifetime() { |
416331ca | 881 | self.bump(); |
74b04a01 | 882 | Lifetime { ident, id: ast::DUMMY_NODE_ID } |
416331ca XL |
883 | } else { |
884 | self.span_bug(self.token.span, "not a lifetime") | |
885 | } | |
886 | } | |
e74abb32 XL |
887 | |
888 | pub(super) fn mk_ty(&self, span: Span, kind: TyKind) -> P<Ty> { | |
1b1a35ee | 889 | P(Ty { kind, span, id: ast::DUMMY_NODE_ID, tokens: None }) |
e74abb32 | 890 | } |
416331ca | 891 | } |