| // Copyright 2014 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| /*! |
| |
| typeck.rs, an introduction |
| |
| The type checker is responsible for: |
| |
| 1. Determining the type of each expression |
| 2. Resolving methods and traits |
| 3. Guaranteeing that most type rules are met ("most?", you say, "why most?" |
| Well, dear reader, read on) |
| |
| The main entry point is `check_crate()`. Type checking operates in |
| several major phases: |
| |
| 1. The collect phase first passes over all items and determines their |
| type, without examining their "innards". |
| |
| 2. Variance inference then runs to compute the variance of each parameter |
| |
| 3. Coherence checks for overlapping or orphaned impls |
| |
| 4. Finally, the check phase then checks function bodies and so forth. |
| Within the check phase, we check each function body one at a time |
| (bodies of function expressions are checked as part of the |
| containing function). Inference is used to supply types wherever |
| they are unknown. The actual checking of a function itself has |
| several phases (check, regionck, writeback), as discussed in the |
| documentation for the `check` module. |
| |
| The type checker is defined into various submodules which are documented |
| independently: |
| |
| - astconv: converts the AST representation of types |
| into the `ty` representation |
| |
| - collect: computes the types of each top-level item and enters them into |
| the `cx.tcache` table for later use |
| |
| - coherence: enforces coherence rules, builds some tables |
| |
| - variance: variance inference |
| |
| - check: walks over function bodies and type checks them, inferring types for |
| local variables, type parameters, etc as necessary. |
| |
| - infer: finds the types to use for each type variable such that |
| all subtyping and assignment constraints are met. In essence, the check |
| module specifies the constraints, and the infer module solves them. |
| |
| # Note |
| |
| This API is completely unstable and subject to change. |
| |
| */ |
| |
| #![crate_name = "rustc_typeck"] |
| #![unstable(feature = "rustc_private", issue = "27812")] |
| #![crate_type = "dylib"] |
| #![crate_type = "rlib"] |
| #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png", |
| html_favicon_url = "https://doc.rust-lang.org/favicon.ico", |
| html_root_url = "https://doc.rust-lang.org/nightly/")] |
| |
| #![allow(non_camel_case_types)] |
| |
| #![feature(box_patterns)] |
| #![feature(box_syntax)] |
| #![feature(iter_arith)] |
| #![feature(quote)] |
| #![feature(rustc_diagnostic_macros)] |
| #![feature(rustc_private)] |
| #![feature(staged_api)] |
| #![feature(cell_extras)] |
| |
| #[macro_use] extern crate log; |
| #[macro_use] extern crate syntax; |
| |
| extern crate arena; |
| extern crate fmt_macros; |
| extern crate rustc; |
| extern crate rustc_platform_intrinsics as intrinsics; |
| extern crate rustc_front; |
| extern crate rustc_back; |
| |
| pub use rustc::dep_graph; |
| pub use rustc::front; |
| pub use rustc::lint; |
| pub use rustc::middle; |
| pub use rustc::session; |
| pub use rustc::util; |
| |
| use front::map as hir_map; |
| use middle::def; |
| use middle::infer::{self, TypeOrigin}; |
| use middle::subst; |
| use middle::ty::{self, Ty, TypeFoldable}; |
| use session::config; |
| use util::common::time; |
| use rustc_front::hir; |
| |
| use syntax::codemap::Span; |
| use syntax::{ast, abi}; |
| |
| use std::cell::RefCell; |
| |
| // NB: This module needs to be declared first so diagnostics are |
| // registered before they are used. |
| pub mod diagnostics; |
| |
| pub mod check; |
| mod rscope; |
| mod astconv; |
| pub mod collect; |
| mod constrained_type_params; |
| pub mod coherence; |
| pub mod variance; |
| |
| pub struct TypeAndSubsts<'tcx> { |
| pub substs: subst::Substs<'tcx>, |
| pub ty: Ty<'tcx>, |
| } |
| |
| pub struct CrateCtxt<'a, 'tcx: 'a> { |
| // A mapping from method call sites to traits that have that method. |
| pub trait_map: ty::TraitMap, |
| /// A vector of every trait accessible in the whole crate |
| /// (i.e. including those from subcrates). This is used only for |
| /// error reporting, and so is lazily initialised and generally |
| /// shouldn't taint the common path (hence the RefCell). |
| pub all_traits: RefCell<Option<check::method::AllTraitsVec>>, |
| pub tcx: &'a ty::ctxt<'tcx>, |
| } |
| |
| // Functions that write types into the node type table |
| fn write_ty_to_tcx<'tcx>(tcx: &ty::ctxt<'tcx>, node_id: ast::NodeId, ty: Ty<'tcx>) { |
| debug!("write_ty_to_tcx({}, {:?})", node_id, ty); |
| assert!(!ty.needs_infer()); |
| tcx.node_type_insert(node_id, ty); |
| } |
| |
| fn write_substs_to_tcx<'tcx>(tcx: &ty::ctxt<'tcx>, |
| node_id: ast::NodeId, |
| item_substs: ty::ItemSubsts<'tcx>) { |
| if !item_substs.is_noop() { |
| debug!("write_substs_to_tcx({}, {:?})", |
| node_id, |
| item_substs); |
| |
| assert!(!item_substs.substs.types.needs_infer()); |
| |
| tcx.tables.borrow_mut().item_substs.insert(node_id, item_substs); |
| } |
| } |
| |
| fn lookup_full_def(tcx: &ty::ctxt, sp: Span, id: ast::NodeId) -> def::Def { |
| match tcx.def_map.borrow().get(&id) { |
| Some(x) => x.full_def(), |
| None => { |
| span_fatal!(tcx.sess, sp, E0242, "internal error looking up a definition") |
| } |
| } |
| } |
| |
| fn require_c_abi_if_variadic(tcx: &ty::ctxt, |
| decl: &hir::FnDecl, |
| abi: abi::Abi, |
| span: Span) { |
| if decl.variadic && abi != abi::C { |
| span_err!(tcx.sess, span, E0045, |
| "variadic function must have C calling convention"); |
| } |
| } |
| |
| fn require_same_types<'a, 'tcx, M>(tcx: &ty::ctxt<'tcx>, |
| maybe_infcx: Option<&infer::InferCtxt<'a, 'tcx>>, |
| t1_is_expected: bool, |
| span: Span, |
| t1: Ty<'tcx>, |
| t2: Ty<'tcx>, |
| msg: M) |
| -> bool where |
| M: FnOnce() -> String, |
| { |
| let result = match maybe_infcx { |
| None => { |
| let infcx = infer::new_infer_ctxt(tcx, &tcx.tables, None, false); |
| infer::mk_eqty(&infcx, t1_is_expected, TypeOrigin::Misc(span), t1, t2) |
| } |
| Some(infcx) => { |
| infer::mk_eqty(infcx, t1_is_expected, TypeOrigin::Misc(span), t1, t2) |
| } |
| }; |
| |
| match result { |
| Ok(_) => true, |
| Err(ref terr) => { |
| let mut err = struct_span_err!(tcx.sess, span, E0211, "{}: {}", msg(), terr); |
| tcx.note_and_explain_type_err(&mut err, terr, span); |
| err.emit(); |
| false |
| } |
| } |
| } |
| |
| fn check_main_fn_ty(ccx: &CrateCtxt, |
| main_id: ast::NodeId, |
| main_span: Span) { |
| let tcx = ccx.tcx; |
| let main_t = tcx.node_id_to_type(main_id); |
| match main_t.sty { |
| ty::TyBareFn(..) => { |
| match tcx.map.find(main_id) { |
| Some(hir_map::NodeItem(it)) => { |
| match it.node { |
| hir::ItemFn(_, _, _, _, ref ps, _) |
| if ps.is_parameterized() => { |
| span_err!(ccx.tcx.sess, main_span, E0131, |
| "main function is not allowed to have type parameters"); |
| return; |
| } |
| _ => () |
| } |
| } |
| _ => () |
| } |
| let main_def_id = tcx.map.local_def_id(main_id); |
| let se_ty = tcx.mk_fn(Some(main_def_id), tcx.mk_bare_fn(ty::BareFnTy { |
| unsafety: hir::Unsafety::Normal, |
| abi: abi::Rust, |
| sig: ty::Binder(ty::FnSig { |
| inputs: Vec::new(), |
| output: ty::FnConverging(tcx.mk_nil()), |
| variadic: false |
| }) |
| })); |
| |
| require_same_types(tcx, None, false, main_span, main_t, se_ty, |
| || { |
| format!("main function expects type: `{}`", |
| se_ty) |
| }); |
| } |
| _ => { |
| tcx.sess.span_bug(main_span, |
| &format!("main has a non-function type: found `{}`", |
| main_t)); |
| } |
| } |
| } |
| |
| fn check_start_fn_ty(ccx: &CrateCtxt, |
| start_id: ast::NodeId, |
| start_span: Span) { |
| let tcx = ccx.tcx; |
| let start_t = tcx.node_id_to_type(start_id); |
| match start_t.sty { |
| ty::TyBareFn(..) => { |
| match tcx.map.find(start_id) { |
| Some(hir_map::NodeItem(it)) => { |
| match it.node { |
| hir::ItemFn(_,_,_,_,ref ps,_) |
| if ps.is_parameterized() => { |
| span_err!(tcx.sess, start_span, E0132, |
| "start function is not allowed to have type parameters"); |
| return; |
| } |
| _ => () |
| } |
| } |
| _ => () |
| } |
| |
| let se_ty = tcx.mk_fn(Some(ccx.tcx.map.local_def_id(start_id)), |
| tcx.mk_bare_fn(ty::BareFnTy { |
| unsafety: hir::Unsafety::Normal, |
| abi: abi::Rust, |
| sig: ty::Binder(ty::FnSig { |
| inputs: vec!( |
| tcx.types.isize, |
| tcx.mk_imm_ptr(tcx.mk_imm_ptr(tcx.types.u8)) |
| ), |
| output: ty::FnConverging(tcx.types.isize), |
| variadic: false, |
| }), |
| })); |
| |
| require_same_types(tcx, None, false, start_span, start_t, se_ty, |
| || { |
| format!("start function expects type: `{}`", |
| se_ty) |
| }); |
| |
| } |
| _ => { |
| tcx.sess.span_bug(start_span, |
| &format!("start has a non-function type: found `{}`", |
| start_t)); |
| } |
| } |
| } |
| |
| fn check_for_entry_fn(ccx: &CrateCtxt) { |
| let tcx = ccx.tcx; |
| match *tcx.sess.entry_fn.borrow() { |
| Some((id, sp)) => match tcx.sess.entry_type.get() { |
| Some(config::EntryMain) => check_main_fn_ty(ccx, id, sp), |
| Some(config::EntryStart) => check_start_fn_ty(ccx, id, sp), |
| Some(config::EntryNone) => {} |
| None => tcx.sess.bug("entry function without a type") |
| }, |
| None => {} |
| } |
| } |
| |
| pub fn check_crate(tcx: &ty::ctxt, trait_map: ty::TraitMap) { |
| let time_passes = tcx.sess.time_passes(); |
| let ccx = CrateCtxt { |
| trait_map: trait_map, |
| all_traits: RefCell::new(None), |
| tcx: tcx |
| }; |
| |
| // this ensures that later parts of type checking can assume that items |
| // have valid types and not error |
| tcx.sess.abort_if_new_errors(|| { |
| time(time_passes, "type collecting", || |
| collect::collect_item_types(tcx)); |
| |
| }); |
| |
| time(time_passes, "variance inference", || |
| variance::infer_variance(tcx)); |
| |
| tcx.sess.abort_if_new_errors(|| { |
| time(time_passes, "coherence checking", || |
| coherence::check_coherence(&ccx)); |
| }); |
| |
| time(time_passes, "wf checking", || |
| check::check_wf_new(&ccx)); |
| |
| time(time_passes, "item-types checking", || |
| check::check_item_types(&ccx)); |
| |
| time(time_passes, "item-bodies checking", || |
| check::check_item_bodies(&ccx)); |
| |
| time(time_passes, "drop-impl checking", || |
| check::check_drop_impls(&ccx)); |
| |
| check_for_entry_fn(&ccx); |
| tcx.sess.abort_if_errors(); |
| } |
| |
| __build_diagnostic_array! { librustc_typeck, DIAGNOSTICS } |