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1 | // Copyright 2014 The Rust Project Developers. See the COPYRIGHT |
2 | // file at the top-level directory of this distribution and at | |
3 | // http://rust-lang.org/COPYRIGHT. | |
4 | // | |
5 | // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | |
6 | // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | |
7 | // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | |
8 | // option. This file may not be copied, modified, or distributed | |
9 | // except according to those terms. | |
10 | ||
11 | /*! | |
12 | ||
13 | typeck.rs, an introduction | |
14 | ||
15 | The type checker is responsible for: | |
16 | ||
17 | 1. Determining the type of each expression | |
18 | 2. Resolving methods and traits | |
19 | 3. Guaranteeing that most type rules are met ("most?", you say, "why most?" | |
20 | Well, dear reader, read on) | |
21 | ||
22 | The main entry point is `check_crate()`. Type checking operates in | |
23 | several major phases: | |
24 | ||
25 | 1. The collect phase first passes over all items and determines their | |
26 | type, without examining their "innards". | |
27 | ||
28 | 2. Variance inference then runs to compute the variance of each parameter | |
29 | ||
30 | 3. Coherence checks for overlapping or orphaned impls | |
31 | ||
32 | 4. Finally, the check phase then checks function bodies and so forth. | |
33 | Within the check phase, we check each function body one at a time | |
34 | (bodies of function expressions are checked as part of the | |
35 | containing function). Inference is used to supply types wherever | |
36 | they are unknown. The actual checking of a function itself has | |
37 | several phases (check, regionck, writeback), as discussed in the | |
38 | documentation for the `check` module. | |
39 | ||
40 | The type checker is defined into various submodules which are documented | |
41 | independently: | |
42 | ||
43 | - astconv: converts the AST representation of types | |
44 | into the `ty` representation | |
45 | ||
46 | - collect: computes the types of each top-level item and enters them into | |
476ff2be | 47 | the `tcx.types` table for later use |
1a4d82fc JJ |
48 | |
49 | - coherence: enforces coherence rules, builds some tables | |
50 | ||
51 | - variance: variance inference | |
52 | ||
53 | - check: walks over function bodies and type checks them, inferring types for | |
54 | local variables, type parameters, etc as necessary. | |
55 | ||
56 | - infer: finds the types to use for each type variable such that | |
57 | all subtyping and assignment constraints are met. In essence, the check | |
58 | module specifies the constraints, and the infer module solves them. | |
59 | ||
60 | # Note | |
61 | ||
62 | This API is completely unstable and subject to change. | |
63 | ||
64 | */ | |
9cc50fc6 | 65 | |
1a4d82fc | 66 | #![crate_name = "rustc_typeck"] |
e9174d1e | 67 | #![unstable(feature = "rustc_private", issue = "27812")] |
1a4d82fc JJ |
68 | #![crate_type = "dylib"] |
69 | #![crate_type = "rlib"] | |
e9174d1e | 70 | #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png", |
62682a34 | 71 | html_favicon_url = "https://doc.rust-lang.org/favicon.ico", |
e9174d1e | 72 | html_root_url = "https://doc.rust-lang.org/nightly/")] |
32a655c1 | 73 | #![deny(warnings)] |
1a4d82fc | 74 | |
85aaf69f SL |
75 | #![allow(non_camel_case_types)] |
76 | ||
77 | #![feature(box_patterns)] | |
1a4d82fc | 78 | #![feature(box_syntax)] |
9e0c209e | 79 | #![feature(conservative_impl_trait)] |
8bb4bdeb | 80 | #![cfg_attr(stage0,feature(field_init_shorthand))] |
32a655c1 | 81 | #![feature(loop_break_value)] |
85aaf69f | 82 | #![feature(quote)] |
1a4d82fc | 83 | #![feature(rustc_diagnostic_macros)] |
85aaf69f | 84 | #![feature(rustc_private)] |
85aaf69f | 85 | #![feature(staged_api)] |
1a4d82fc JJ |
86 | |
87 | #[macro_use] extern crate log; | |
88 | #[macro_use] extern crate syntax; | |
3157f602 | 89 | extern crate syntax_pos; |
1a4d82fc JJ |
90 | |
91 | extern crate arena; | |
85aaf69f | 92 | extern crate fmt_macros; |
54a0048b | 93 | #[macro_use] extern crate rustc; |
e9174d1e | 94 | extern crate rustc_platform_intrinsics as intrinsics; |
b039eaaf | 95 | extern crate rustc_back; |
54a0048b SL |
96 | extern crate rustc_const_math; |
97 | extern crate rustc_const_eval; | |
476ff2be | 98 | extern crate rustc_data_structures; |
3157f602 | 99 | extern crate rustc_errors as errors; |
1a4d82fc | 100 | |
9cc50fc6 | 101 | pub use rustc::dep_graph; |
54a0048b | 102 | pub use rustc::hir; |
1a4d82fc | 103 | pub use rustc::lint; |
1a4d82fc JJ |
104 | pub use rustc::middle; |
105 | pub use rustc::session; | |
106 | pub use rustc::util; | |
107 | ||
7453a54e | 108 | use dep_graph::DepNode; |
54a0048b | 109 | use hir::map as hir_map; |
476ff2be | 110 | use rustc::infer::InferOk; |
54a0048b | 111 | use rustc::ty::subst::Substs; |
476ff2be | 112 | use rustc::ty::{self, Ty, TyCtxt}; |
8bb4bdeb XL |
113 | use rustc::ty::maps::Providers; |
114 | use rustc::traits::{ObligationCause, ObligationCauseCode, Reveal}; | |
476ff2be | 115 | use session::config; |
1a4d82fc | 116 | use util::common::time; |
1a4d82fc | 117 | |
7453a54e SL |
118 | use syntax::ast; |
119 | use syntax::abi::Abi; | |
3157f602 | 120 | use syntax_pos::Span; |
1a4d82fc | 121 | |
476ff2be | 122 | use std::iter; |
85aaf69f SL |
123 | // NB: This module needs to be declared first so diagnostics are |
124 | // registered before they are used. | |
125 | pub mod diagnostics; | |
126 | ||
62682a34 | 127 | pub mod check; |
a7813a04 | 128 | pub mod check_unused; |
1a4d82fc | 129 | mod astconv; |
62682a34 | 130 | pub mod collect; |
85aaf69f | 131 | mod constrained_type_params; |
476ff2be | 132 | mod impl_wf_check; |
62682a34 SL |
133 | pub mod coherence; |
134 | pub mod variance; | |
1a4d82fc | 135 | |
c34b1796 | 136 | pub struct TypeAndSubsts<'tcx> { |
9e0c209e | 137 | pub substs: &'tcx Substs<'tcx>, |
1a4d82fc JJ |
138 | pub ty: Ty<'tcx>, |
139 | } | |
140 | ||
a7813a04 | 141 | fn require_c_abi_if_variadic(tcx: TyCtxt, |
e9174d1e | 142 | decl: &hir::FnDecl, |
7453a54e | 143 | abi: Abi, |
c1a9b12d | 144 | span: Span) { |
7453a54e | 145 | if decl.variadic && abi != Abi::C { |
5bcae85e | 146 | let mut err = struct_span_err!(tcx.sess, span, E0045, |
c1a9b12d | 147 | "variadic function must have C calling convention"); |
5bcae85e SL |
148 | err.span_label(span, &("variadics require C calling conventions").to_string()) |
149 | .emit(); | |
c1a9b12d SL |
150 | } |
151 | } | |
152 | ||
8bb4bdeb | 153 | fn require_same_types<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
476ff2be | 154 | cause: &ObligationCause<'tcx>, |
c30ab7b3 SL |
155 | expected: Ty<'tcx>, |
156 | actual: Ty<'tcx>) | |
a7813a04 | 157 | -> bool { |
8bb4bdeb | 158 | tcx.infer_ctxt((), Reveal::UserFacing).enter(|infcx| { |
476ff2be | 159 | match infcx.eq_types(false, &cause, expected, actual) { |
c30ab7b3 SL |
160 | Ok(InferOk { obligations, .. }) => { |
161 | // FIXME(#32730) propagate obligations | |
162 | assert!(obligations.is_empty()); | |
163 | true | |
164 | } | |
165 | Err(err) => { | |
32a655c1 | 166 | infcx.report_mismatched_types(cause, expected, actual, err).emit(); |
c30ab7b3 SL |
167 | false |
168 | } | |
1a4d82fc | 169 | } |
a7813a04 | 170 | }) |
1a4d82fc JJ |
171 | } |
172 | ||
8bb4bdeb XL |
173 | fn check_main_fn_ty<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
174 | main_id: ast::NodeId, | |
175 | main_span: Span) { | |
32a655c1 | 176 | let main_def_id = tcx.hir.local_def_id(main_id); |
476ff2be | 177 | let main_t = tcx.item_type(main_def_id); |
1a4d82fc | 178 | match main_t.sty { |
54a0048b | 179 | ty::TyFnDef(..) => { |
32a655c1 | 180 | match tcx.hir.find(main_id) { |
e9174d1e | 181 | Some(hir_map::NodeItem(it)) => { |
1a4d82fc | 182 | match it.node { |
9e0c209e SL |
183 | hir::ItemFn(.., ref generics, _) => { |
184 | if generics.is_parameterized() { | |
8bb4bdeb | 185 | struct_span_err!(tcx.sess, generics.span, E0131, |
5bcae85e | 186 | "main function is not allowed to have type parameters") |
9e0c209e | 187 | .span_label(generics.span, |
5bcae85e SL |
188 | &format!("main cannot have type parameters")) |
189 | .emit(); | |
190 | return; | |
191 | } | |
1a4d82fc JJ |
192 | } |
193 | _ => () | |
194 | } | |
195 | } | |
196 | _ => () | |
197 | } | |
c30ab7b3 | 198 | let substs = tcx.intern_substs(&[]); |
a7813a04 | 199 | let se_ty = tcx.mk_fn_def(main_def_id, substs, |
8bb4bdeb XL |
200 | ty::Binder(tcx.mk_fn_sig( |
201 | iter::empty(), | |
202 | tcx.mk_nil(), | |
203 | false, | |
204 | hir::Unsafety::Normal, | |
205 | Abi::Rust | |
206 | )) | |
207 | ); | |
1a4d82fc | 208 | |
5bcae85e | 209 | require_same_types( |
8bb4bdeb | 210 | tcx, |
476ff2be | 211 | &ObligationCause::new(main_span, main_id, ObligationCauseCode::MainFunctionType), |
c30ab7b3 SL |
212 | se_ty, |
213 | main_t); | |
1a4d82fc JJ |
214 | } |
215 | _ => { | |
54a0048b SL |
216 | span_bug!(main_span, |
217 | "main has a non-function type: found `{}`", | |
218 | main_t); | |
1a4d82fc JJ |
219 | } |
220 | } | |
221 | } | |
222 | ||
8bb4bdeb XL |
223 | fn check_start_fn_ty<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
224 | start_id: ast::NodeId, | |
225 | start_span: Span) { | |
226 | let start_def_id = tcx.hir.local_def_id(start_id); | |
476ff2be | 227 | let start_t = tcx.item_type(start_def_id); |
1a4d82fc | 228 | match start_t.sty { |
54a0048b | 229 | ty::TyFnDef(..) => { |
32a655c1 | 230 | match tcx.hir.find(start_id) { |
e9174d1e | 231 | Some(hir_map::NodeItem(it)) => { |
1a4d82fc | 232 | match it.node { |
9e0c209e | 233 | hir::ItemFn(..,ref ps,_) |
1a4d82fc | 234 | if ps.is_parameterized() => { |
9e0c209e | 235 | struct_span_err!(tcx.sess, ps.span, E0132, |
5bcae85e | 236 | "start function is not allowed to have type parameters") |
9e0c209e | 237 | .span_label(ps.span, |
5bcae85e SL |
238 | &format!("start function cannot have type parameters")) |
239 | .emit(); | |
1a4d82fc JJ |
240 | return; |
241 | } | |
242 | _ => () | |
243 | } | |
244 | } | |
245 | _ => () | |
246 | } | |
247 | ||
c30ab7b3 | 248 | let substs = tcx.intern_substs(&[]); |
a7813a04 | 249 | let se_ty = tcx.mk_fn_def(start_def_id, substs, |
8bb4bdeb | 250 | ty::Binder(tcx.mk_fn_sig( |
476ff2be | 251 | [ |
c34b1796 | 252 | tcx.types.isize, |
c1a9b12d | 253 | tcx.mk_imm_ptr(tcx.mk_imm_ptr(tcx.types.u8)) |
476ff2be SL |
254 | ].iter().cloned(), |
255 | tcx.types.isize, | |
256 | false, | |
8bb4bdeb XL |
257 | hir::Unsafety::Normal, |
258 | Abi::Rust | |
259 | )) | |
260 | ); | |
1a4d82fc | 261 | |
5bcae85e | 262 | require_same_types( |
8bb4bdeb | 263 | tcx, |
476ff2be | 264 | &ObligationCause::new(start_span, start_id, ObligationCauseCode::StartFunctionType), |
c30ab7b3 SL |
265 | se_ty, |
266 | start_t); | |
1a4d82fc JJ |
267 | } |
268 | _ => { | |
54a0048b SL |
269 | span_bug!(start_span, |
270 | "start has a non-function type: found `{}`", | |
271 | start_t); | |
1a4d82fc JJ |
272 | } |
273 | } | |
274 | } | |
275 | ||
8bb4bdeb | 276 | fn check_for_entry_fn<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) { |
7453a54e | 277 | let _task = tcx.dep_graph.in_task(DepNode::CheckEntryFn); |
3157f602 XL |
278 | if let Some((id, sp)) = *tcx.sess.entry_fn.borrow() { |
279 | match tcx.sess.entry_type.get() { | |
8bb4bdeb XL |
280 | Some(config::EntryMain) => check_main_fn_ty(tcx, id, sp), |
281 | Some(config::EntryStart) => check_start_fn_ty(tcx, id, sp), | |
1a4d82fc | 282 | Some(config::EntryNone) => {} |
54a0048b | 283 | None => bug!("entry function without a type") |
3157f602 | 284 | } |
1a4d82fc JJ |
285 | } |
286 | } | |
287 | ||
8bb4bdeb XL |
288 | pub fn provide(providers: &mut Providers) { |
289 | collect::provide(providers); | |
290 | coherence::provide(providers); | |
291 | check::provide(providers); | |
292 | } | |
293 | ||
5bcae85e | 294 | pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) |
8bb4bdeb | 295 | -> Result<(), usize> { |
1a4d82fc | 296 | let time_passes = tcx.sess.time_passes(); |
1a4d82fc | 297 | |
1a4d82fc JJ |
298 | // this ensures that later parts of type checking can assume that items |
299 | // have valid types and not error | |
54a0048b | 300 | tcx.sess.track_errors(|| { |
9cc50fc6 | 301 | time(time_passes, "type collecting", || |
8bb4bdeb | 302 | collect::collect_item_types(tcx)); |
9cc50fc6 | 303 | |
54a0048b | 304 | })?; |
1a4d82fc | 305 | |
e9174d1e | 306 | time(time_passes, "variance inference", || |
1a4d82fc JJ |
307 | variance::infer_variance(tcx)); |
308 | ||
476ff2be SL |
309 | tcx.sess.track_errors(|| { |
310 | time(time_passes, "impl wf inference", || | |
8bb4bdeb | 311 | impl_wf_check::impl_wf_check(tcx)); |
476ff2be SL |
312 | })?; |
313 | ||
54a0048b | 314 | tcx.sess.track_errors(|| { |
9cc50fc6 | 315 | time(time_passes, "coherence checking", || |
8bb4bdeb | 316 | coherence::check_coherence(tcx)); |
54a0048b | 317 | })?; |
1a4d82fc | 318 | |
8bb4bdeb | 319 | time(time_passes, "wf checking", || check::check_wf_new(tcx))?; |
1a4d82fc | 320 | |
8bb4bdeb | 321 | time(time_passes, "item-types checking", || check::check_item_types(tcx))?; |
e9174d1e | 322 | |
8bb4bdeb | 323 | time(time_passes, "item-bodies checking", || check::check_item_bodies(tcx))?; |
e9174d1e | 324 | |
a7813a04 | 325 | check_unused::check_crate(tcx); |
8bb4bdeb | 326 | check_for_entry_fn(tcx); |
7453a54e SL |
327 | |
328 | let err_count = tcx.sess.err_count(); | |
329 | if err_count == 0 { | |
8bb4bdeb | 330 | Ok(()) |
7453a54e SL |
331 | } else { |
332 | Err(err_count) | |
333 | } | |
1a4d82fc | 334 | } |
d9579d0f | 335 | |
d9579d0f | 336 | __build_diagnostic_array! { librustc_typeck, DIAGNOSTICS } |