/*!
-typeck.rs, an introduction
+# typeck.rs
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?"
+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
+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
+2. Variance inference then runs to compute the variance of each parameter.
-3. Coherence checks for overlapping or orphaned impls
+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
independently:
- astconv: converts the AST representation of types
- into the `ty` representation
+ into the `ty` representation.
- collect: computes the types of each top-level item and enters them into
- the `tcx.types` table for later use
+ the `tcx.types` table for later use.
-- coherence: enforces coherence rules, builds some tables
+- coherence: enforces coherence rules, builds some tables.
- variance: variance inference
all subtyping and assignment constraints are met. In essence, the check
module specifies the constraints, and the infer module solves them.
-# Note
+## Note
This API is completely unstable and subject to change.
extern crate rustc_target;
extern crate smallvec;
-use rustc::hir;
-use rustc::lint;
-use rustc::middle;
-use rustc::session;
-use rustc::util;
-
-use hir::Node;
-use rustc::infer::InferOk;
-use rustc::ty::subst::Substs;
-use rustc::ty::{self, Ty, TyCtxt};
-use rustc::ty::query::Providers;
-use rustc::traits::{ObligationCause, ObligationCauseCode, TraitEngine, TraitEngineExt};
-use rustc::util::profiling::ProfileCategory;
-use session::{CompileIncomplete, config};
-use util::common::time;
-
-use syntax::ast;
-use rustc_target::spec::abi::Abi;
-use syntax_pos::Span;
-
-use std::iter;
-
-// NB: This module needs to be declared first so diagnostics are
+// N.B., this module needs to be declared first so diagnostics are
// registered before they are used.
mod diagnostics;
mod outlives;
mod variance;
+use hir::Node;
+use rustc_target::spec::abi::Abi;
+use rustc::hir;
+use rustc::infer::InferOk;
+use rustc::lint;
+use rustc::middle;
+use rustc::session;
+use rustc::traits::{ObligationCause, ObligationCauseCode, TraitEngine, TraitEngineExt};
+use rustc::ty::subst::Substs;
+use rustc::ty::{self, Ty, TyCtxt};
+use rustc::ty::query::Providers;
+use rustc::util;
+use rustc::util::profiling::ProfileCategory;
+use session::{CompileIncomplete, config};
+use syntax_pos::Span;
+use syntax::ast;
+use util::common::time;
+
+use std::iter;
+
pub struct TypeAndSubsts<'tcx> {
substs: &'tcx Substs<'tcx>,
ty: Ty<'tcx>,
fn check_main_fn_ty<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
main_id: ast::NodeId,
main_span: Span) {
- let main_def_id = tcx.hir.local_def_id(main_id);
+ let main_def_id = tcx.hir().local_def_id(main_id);
let main_t = tcx.type_of(main_def_id);
match main_t.sty {
ty::FnDef(..) => {
- if let Some(Node::Item(it)) = tcx.hir.find(main_id) {
+ if let Some(Node::Item(it)) = tcx.hir().find(main_id) {
if let hir::ItemKind::Fn(.., ref generics, _) = it.node {
let mut error = false;
if !generics.params.is_empty() {
fn check_start_fn_ty<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
start_id: ast::NodeId,
start_span: Span) {
- let start_def_id = tcx.hir.local_def_id(start_id);
+ let start_def_id = tcx.hir().local_def_id(start_id);
let start_t = tcx.type_of(start_def_id);
match start_t.sty {
ty::FnDef(..) => {
- if let Some(Node::Item(it)) = tcx.hir.find(start_id) {
+ if let Some(Node::Item(it)) = tcx.hir().find(start_id) {
if let hir::ItemKind::Fn(.., ref generics, _) = it.node {
let mut error = false;
if !generics.params.is_empty() {
// In case there are any projections etc, find the "environment"
// def-id that will be used to determine the traits/predicates in
// scope. This is derived from the enclosing item-like thing.
- let env_node_id = tcx.hir.get_parent(hir_ty.id);
- let env_def_id = tcx.hir.local_def_id(env_node_id);
+ let env_node_id = tcx.hir().get_parent(hir_ty.id);
+ let env_def_id = tcx.hir().local_def_id(env_node_id);
let item_cx = self::collect::ItemCtxt::new(tcx, env_def_id);
astconv::AstConv::ast_ty_to_ty(&item_cx, hir_ty)
// In case there are any projections etc, find the "environment"
// def-id that will be used to determine the traits/predicates in
// scope. This is derived from the enclosing item-like thing.
- let env_node_id = tcx.hir.get_parent(hir_trait.ref_id);
- let env_def_id = tcx.hir.local_def_id(env_node_id);
+ let env_node_id = tcx.hir().get_parent(hir_trait.ref_id);
+ let env_def_id = tcx.hir().local_def_id(env_node_id);
let item_cx = self::collect::ItemCtxt::new(tcx, env_def_id);
let mut projections = Vec::new();
let (principal, _) = astconv::AstConv::instantiate_poly_trait_ref_inner(
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