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// Type resolution: the phase that finds all the types in the AST with
// unresolved type variables and replaces "ty_var" types with their
// substitutions.
use crate::check::FnCtxt;
use errors::DiagnosticBuilder;
use rustc::hir;
use rustc::hir::def_id::{DefId, DefIndex};
use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc::infer::InferCtxt;
use rustc::ty::adjustment::{Adjust, Adjustment, PointerCast};
use rustc::ty::fold::{TypeFoldable, TypeFolder};
use rustc::ty::{self, Ty, TyCtxt};
use rustc::util::nodemap::DefIdSet;
use rustc_data_structures::sync::Lrc;
use std::mem;
use syntax::symbol::sym;
use syntax_pos::Span;
///////////////////////////////////////////////////////////////////////////
// Entry point
// During type inference, partially inferred types are
// represented using Type variables (ty::Infer). These don't appear in
// the final TypeckTables since all of the types should have been
// inferred once typeck_tables_of is done.
// When type inference is running however, having to update the typeck
// tables every time a new type is inferred would be unreasonably slow,
// so instead all of the replacement happens at the end in
// resolve_type_vars_in_body, which creates a new TypeTables which
// doesn't contain any inference types.
impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
pub fn resolve_type_vars_in_body(&self, body: &'tcx hir::Body) -> &'tcx ty::TypeckTables<'tcx> {
let item_id = self.tcx.hir().body_owner(body.id());
let item_def_id = self.tcx.hir().local_def_id(item_id);
// This attribute causes us to dump some writeback information
// in the form of errors, which is uSymbolfor unit tests.
let rustc_dump_user_substs = self.tcx.has_attr(item_def_id, sym::rustc_dump_user_substs);
let mut wbcx = WritebackCx::new(self, body, rustc_dump_user_substs);
for arg in &body.arguments {
wbcx.visit_node_id(arg.pat.span, arg.hir_id);
}
// Type only exists for constants and statics, not functions.
match self.tcx.hir().body_owner_kind(item_id) {
hir::BodyOwnerKind::Const | hir::BodyOwnerKind::Static(_) => {
wbcx.visit_node_id(body.value.span, item_id);
}
hir::BodyOwnerKind::Closure | hir::BodyOwnerKind::Fn => (),
}
wbcx.visit_body(body);
wbcx.visit_upvar_capture_map();
wbcx.visit_closures();
wbcx.visit_liberated_fn_sigs();
wbcx.visit_fru_field_types();
wbcx.visit_opaque_types(body.value.span);
wbcx.visit_coercion_casts();
wbcx.visit_free_region_map();
wbcx.visit_user_provided_tys();
wbcx.visit_user_provided_sigs();
let used_trait_imports = mem::replace(
&mut self.tables.borrow_mut().used_trait_imports,
Lrc::new(DefIdSet::default()),
);
debug!(
"used_trait_imports({:?}) = {:?}",
item_def_id, used_trait_imports
);
wbcx.tables.used_trait_imports = used_trait_imports;
wbcx.tables.upvar_list = mem::replace(
&mut self.tables.borrow_mut().upvar_list,
Default::default(),
);
wbcx.tables.tainted_by_errors = self.is_tainted_by_errors();
debug!(
"writeback: tables for {:?} are {:#?}",
item_def_id, wbcx.tables
);
self.tcx.arena.alloc(wbcx.tables)
}
}
///////////////////////////////////////////////////////////////////////////
// The Writeback context. This visitor walks the AST, checking the
// fn-specific tables to find references to types or regions. It
// resolves those regions to remove inference variables and writes the
// final result back into the master tables in the tcx. Here and
// there, it applies a few ad-hoc checks that were not convenient to
// do elsewhere.
struct WritebackCx<'cx, 'tcx> {
fcx: &'cx FnCtxt<'cx, 'tcx>,
tables: ty::TypeckTables<'tcx>,
body: &'tcx hir::Body,
rustc_dump_user_substs: bool,
}
impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
fn new(
fcx: &'cx FnCtxt<'cx, 'tcx>,
body: &'tcx hir::Body,
rustc_dump_user_substs: bool,
) -> WritebackCx<'cx, 'tcx> {
let owner = body.id().hir_id;
WritebackCx {
fcx,
tables: ty::TypeckTables::empty(Some(DefId::local(owner.owner))),
body,
rustc_dump_user_substs,
}
}
fn tcx(&self) -> TyCtxt<'tcx> {
self.fcx.tcx
}
fn write_ty_to_tables(&mut self, hir_id: hir::HirId, ty: Ty<'tcx>) {
debug!("write_ty_to_tables({:?}, {:?})", hir_id, ty);
assert!(!ty.needs_infer() && !ty.has_placeholders());
self.tables.node_types_mut().insert(hir_id, ty);
}
// Hacky hack: During type-checking, we treat *all* operators
// as potentially overloaded. But then, during writeback, if
// we observe that something like `a+b` is (known to be)
// operating on scalars, we clear the overload.
fn fix_scalar_builtin_expr(&mut self, e: &hir::Expr) {
match e.node {
hir::ExprKind::Unary(hir::UnNeg, ref inner)
| hir::ExprKind::Unary(hir::UnNot, ref inner) => {
let inner_ty = self.fcx.node_ty(inner.hir_id);
let inner_ty = self.fcx.resolve_vars_if_possible(&inner_ty);
if inner_ty.is_scalar() {
let mut tables = self.fcx.tables.borrow_mut();
tables.type_dependent_defs_mut().remove(e.hir_id);
tables.node_substs_mut().remove(e.hir_id);
}
}
hir::ExprKind::Binary(ref op, ref lhs, ref rhs)
| hir::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
let lhs_ty = self.fcx.node_ty(lhs.hir_id);
let lhs_ty = self.fcx.resolve_vars_if_possible(&lhs_ty);
let rhs_ty = self.fcx.node_ty(rhs.hir_id);
let rhs_ty = self.fcx.resolve_vars_if_possible(&rhs_ty);
if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
let mut tables = self.fcx.tables.borrow_mut();
tables.type_dependent_defs_mut().remove(e.hir_id);
tables.node_substs_mut().remove(e.hir_id);
match e.node {
hir::ExprKind::Binary(..) => {
if !op.node.is_by_value() {
let mut adjustments = tables.adjustments_mut();
adjustments.get_mut(lhs.hir_id).map(|a| a.pop());
adjustments.get_mut(rhs.hir_id).map(|a| a.pop());
}
}
hir::ExprKind::AssignOp(..) => {
tables
.adjustments_mut()
.get_mut(lhs.hir_id)
.map(|a| a.pop());
}
_ => {}
}
}
}
_ => {}
}
}
// Similar to operators, indexing is always assumed to be overloaded
// Here, correct cases where an indexing expression can be simplified
// to use builtin indexing because the index type is known to be
// usize-ish
fn fix_index_builtin_expr(&mut self, e: &hir::Expr) {
if let hir::ExprKind::Index(ref base, ref index) = e.node {
let mut tables = self.fcx.tables.borrow_mut();
// All valid indexing looks like this; might encounter non-valid indexes at this point
if let ty::Ref(_, base_ty, _) = tables.expr_ty_adjusted(&base).sty {
let index_ty = tables.expr_ty_adjusted(&index);
let index_ty = self.fcx.resolve_vars_if_possible(&index_ty);
if base_ty.builtin_index().is_some() && index_ty == self.fcx.tcx.types.usize {
// Remove the method call record
tables.type_dependent_defs_mut().remove(e.hir_id);
tables.node_substs_mut().remove(e.hir_id);
tables.adjustments_mut().get_mut(base.hir_id).map(|a| {
// Discard the need for a mutable borrow
match a.pop() {
// Extra adjustment made when indexing causes a drop
// of size information - we need to get rid of it
// Since this is "after" the other adjustment to be
// discarded, we do an extra `pop()`
Some(Adjustment {
kind: Adjust::Pointer(PointerCast::Unsize),
..
}) => {
// So the borrow discard actually happens here
a.pop();
}
_ => {}
}
});
}
}
}
}
}
///////////////////////////////////////////////////////////////////////////
// Impl of Visitor for Resolver
//
// This is the master code which walks the AST. It delegates most of
// the heavy lifting to the generic visit and resolve functions
// below. In general, a function is made into a `visitor` if it must
// traffic in node-ids or update tables in the type context etc.
impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
NestedVisitorMap::None
}
fn visit_expr(&mut self, e: &'tcx hir::Expr) {
self.fix_scalar_builtin_expr(e);
self.fix_index_builtin_expr(e);
self.visit_node_id(e.span, e.hir_id);
match e.node {
hir::ExprKind::Closure(_, _, body, _, _) => {
let body = self.fcx.tcx.hir().body(body);
for arg in &body.arguments {
self.visit_node_id(e.span, arg.hir_id);
}
self.visit_body(body);
}
hir::ExprKind::Struct(_, ref fields, _) => {
for field in fields {
self.visit_field_id(field.hir_id);
}
}
hir::ExprKind::Field(..) => {
self.visit_field_id(e.hir_id);
}
_ => {}
}
intravisit::walk_expr(self, e);
}
fn visit_block(&mut self, b: &'tcx hir::Block) {
self.visit_node_id(b.span, b.hir_id);
intravisit::walk_block(self, b);
}
fn visit_pat(&mut self, p: &'tcx hir::Pat) {
match p.node {
hir::PatKind::Binding(..) => {
if let Some(&bm) = self.fcx.tables.borrow().pat_binding_modes().get(p.hir_id) {
self.tables.pat_binding_modes_mut().insert(p.hir_id, bm);
} else {
self.tcx()
.sess
.delay_span_bug(p.span, "missing binding mode");
}
}
hir::PatKind::Struct(_, ref fields, _) => {
for field in fields {
self.visit_field_id(field.node.hir_id);
}
}
_ => {}
};
self.visit_pat_adjustments(p.span, p.hir_id);
self.visit_node_id(p.span, p.hir_id);
intravisit::walk_pat(self, p);
}
fn visit_local(&mut self, l: &'tcx hir::Local) {
intravisit::walk_local(self, l);
let var_ty = self.fcx.local_ty(l.span, l.hir_id).decl_ty;
let var_ty = self.resolve(&var_ty, &l.span);
self.write_ty_to_tables(l.hir_id, var_ty);
}
fn visit_ty(&mut self, hir_ty: &'tcx hir::Ty) {
intravisit::walk_ty(self, hir_ty);
let ty = self.fcx.node_ty(hir_ty.hir_id);
let ty = self.resolve(&ty, &hir_ty.span);
self.write_ty_to_tables(hir_ty.hir_id, ty);
}
}
impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
fn visit_upvar_capture_map(&mut self) {
for (upvar_id, upvar_capture) in self.fcx.tables.borrow().upvar_capture_map.iter() {
let new_upvar_capture = match *upvar_capture {
ty::UpvarCapture::ByValue => ty::UpvarCapture::ByValue,
ty::UpvarCapture::ByRef(ref upvar_borrow) => {
let r = upvar_borrow.region;
let r = self.resolve(&r, &upvar_id.var_path.hir_id);
ty::UpvarCapture::ByRef(ty::UpvarBorrow {
kind: upvar_borrow.kind,
region: r,
})
}
};
debug!(
"Upvar capture for {:?} resolved to {:?}",
upvar_id, new_upvar_capture
);
self.tables
.upvar_capture_map
.insert(*upvar_id, new_upvar_capture);
}
}
fn visit_closures(&mut self) {
let fcx_tables = self.fcx.tables.borrow();
debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
let common_local_id_root = fcx_tables.local_id_root.unwrap();
for (&id, &origin) in fcx_tables.closure_kind_origins().iter() {
let hir_id = hir::HirId {
owner: common_local_id_root.index,
local_id: id,
};
self.tables
.closure_kind_origins_mut()
.insert(hir_id, origin);
}
}
fn visit_coercion_casts(&mut self) {
let fcx_tables = self.fcx.tables.borrow();
let fcx_coercion_casts = fcx_tables.coercion_casts();
debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
for local_id in fcx_coercion_casts {
self.tables.set_coercion_cast(*local_id);
}
}
fn visit_free_region_map(&mut self) {
self.tables.free_region_map = self.fcx.tables.borrow().free_region_map.clone();
debug_assert!(!self.tables.free_region_map.elements().any(|r| r.has_local_value()));
}
fn visit_user_provided_tys(&mut self) {
let fcx_tables = self.fcx.tables.borrow();
debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
let common_local_id_root = fcx_tables.local_id_root.unwrap();
let mut errors_buffer = Vec::new();
for (&local_id, c_ty) in fcx_tables.user_provided_types().iter() {
let hir_id = hir::HirId {
owner: common_local_id_root.index,
local_id,
};
if cfg!(debug_assertions) && c_ty.has_local_value() {
span_bug!(
hir_id.to_span(self.fcx.tcx),
"writeback: `{:?}` is a local value",
c_ty
);
};
self.tables
.user_provided_types_mut()
.insert(hir_id, c_ty.clone());
if let ty::UserType::TypeOf(_, user_substs) = c_ty.value {
if self.rustc_dump_user_substs {
// This is a unit-testing mechanism.
let span = self.tcx().hir().span(hir_id);
// We need to buffer the errors in order to guarantee a consistent
// order when emitting them.
let err = self.tcx().sess.struct_span_err(
span,
&format!("user substs: {:?}", user_substs)
);
err.buffer(&mut errors_buffer);
}
}
}
if !errors_buffer.is_empty() {
errors_buffer.sort_by_key(|diag| diag.span.primary_span());
for diag in errors_buffer.drain(..) {
DiagnosticBuilder::new_diagnostic(self.tcx().sess.diagnostic(), diag).emit();
}
}
}
fn visit_user_provided_sigs(&mut self) {
let fcx_tables = self.fcx.tables.borrow();
debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
for (&def_id, c_sig) in fcx_tables.user_provided_sigs.iter() {
if cfg!(debug_assertions) && c_sig.has_local_value() {
span_bug!(
self.fcx.tcx.hir().span_if_local(def_id).unwrap(),
"writeback: `{:?}` is a local value",
c_sig
);
};
self.tables
.user_provided_sigs
.insert(def_id, c_sig.clone());
}
}
fn visit_opaque_types(&mut self, span: Span) {
for (&def_id, opaque_defn) in self.fcx.opaque_types.borrow().iter() {
let hir_id = self.tcx().hir().as_local_hir_id(def_id).unwrap();
let instantiated_ty = self.resolve(&opaque_defn.concrete_ty, &hir_id);
debug_assert!(!instantiated_ty.has_escaping_bound_vars());
// Prevent:
// * `fn foo<T>() -> Foo<T>`
// * `fn foo<T: Bound + Other>() -> Foo<T>`
// from being defining.
// Also replace all generic params with the ones from the existential type
// definition so that
// ```rust
// existential type Foo<T>: 'static;
// fn foo<U>() -> Foo<U> { .. }
// ```
// figures out the concrete type with `U`, but the stored type is with `T`.
let definition_ty = self.fcx.infer_opaque_definition_from_instantiation(
def_id, opaque_defn, instantiated_ty, span);
if let ty::Opaque(defin_ty_def_id, _substs) = definition_ty.sty {
if def_id == defin_ty_def_id {
// Concrete type resolved to the existential type itself.
// Force a cycle error.
// FIXME(oli-obk): we could just not insert it into `concrete_existential_types`
// which simply would make this use not a defining use.
self.tcx().at(span).type_of(defin_ty_def_id);
}
}
if !opaque_defn.substs.has_local_value() {
let new = ty::ResolvedOpaqueTy {
concrete_type: definition_ty,
substs: opaque_defn.substs,
};
let old = self.tables
.concrete_existential_types
.insert(def_id, new);
if let Some(old) = old {
if old.concrete_type != definition_ty || old.substs != opaque_defn.substs {
span_bug!(
span,
"visit_opaque_types tried to write \
different types for the same existential type: {:?}, {:?}, {:?}, {:?}",
def_id,
definition_ty,
opaque_defn,
old,
);
}
}
} else {
self.tcx().sess.delay_span_bug(
span,
"`opaque_defn` is a local value",
);
}
}
}
fn visit_field_id(&mut self, hir_id: hir::HirId) {
if let Some(index) = self.fcx
.tables
.borrow_mut()
.field_indices_mut()
.remove(hir_id)
{
self.tables.field_indices_mut().insert(hir_id, index);
}
}
fn visit_node_id(&mut self, span: Span, hir_id: hir::HirId) {
// Export associated path extensions and method resolutions.
if let Some(def) = self.fcx
.tables
.borrow_mut()
.type_dependent_defs_mut()
.remove(hir_id)
{
self.tables.type_dependent_defs_mut().insert(hir_id, def);
}
// Resolve any borrowings for the node with id `node_id`
self.visit_adjustments(span, hir_id);
// Resolve the type of the node with id `node_id`
let n_ty = self.fcx.node_ty(hir_id);
let n_ty = self.resolve(&n_ty, &span);
self.write_ty_to_tables(hir_id, n_ty);
debug!("node {:?} has type {:?}", hir_id, n_ty);
// Resolve any substitutions
if let Some(substs) = self.fcx.tables.borrow().node_substs_opt(hir_id) {
let substs = self.resolve(&substs, &span);
debug!("write_substs_to_tcx({:?}, {:?})", hir_id, substs);
assert!(!substs.needs_infer() && !substs.has_placeholders());
self.tables.node_substs_mut().insert(hir_id, substs);
}
}
fn visit_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
let adjustment = self.fcx
.tables
.borrow_mut()
.adjustments_mut()
.remove(hir_id);
match adjustment {
None => {
debug!("no adjustments for node {:?}", hir_id);
}
Some(adjustment) => {
let resolved_adjustment = self.resolve(&adjustment, &span);
debug!(
"adjustments for node {:?}: {:?}",
hir_id, resolved_adjustment
);
self.tables
.adjustments_mut()
.insert(hir_id, resolved_adjustment);
}
}
}
fn visit_pat_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
let adjustment = self.fcx
.tables
.borrow_mut()
.pat_adjustments_mut()
.remove(hir_id);
match adjustment {
None => {
debug!("no pat_adjustments for node {:?}", hir_id);
}
Some(adjustment) => {
let resolved_adjustment = self.resolve(&adjustment, &span);
debug!(
"pat_adjustments for node {:?}: {:?}",
hir_id, resolved_adjustment
);
self.tables
.pat_adjustments_mut()
.insert(hir_id, resolved_adjustment);
}
}
}
fn visit_liberated_fn_sigs(&mut self) {
let fcx_tables = self.fcx.tables.borrow();
debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
let common_local_id_root = fcx_tables.local_id_root.unwrap();
for (&local_id, fn_sig) in fcx_tables.liberated_fn_sigs().iter() {
let hir_id = hir::HirId {
owner: common_local_id_root.index,
local_id,
};
let fn_sig = self.resolve(fn_sig, &hir_id);
self.tables
.liberated_fn_sigs_mut()
.insert(hir_id, fn_sig.clone());
}
}
fn visit_fru_field_types(&mut self) {
let fcx_tables = self.fcx.tables.borrow();
debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
let common_local_id_root = fcx_tables.local_id_root.unwrap();
for (&local_id, ftys) in fcx_tables.fru_field_types().iter() {
let hir_id = hir::HirId {
owner: common_local_id_root.index,
local_id,
};
let ftys = self.resolve(ftys, &hir_id);
self.tables.fru_field_types_mut().insert(hir_id, ftys);
}
}
fn resolve<T>(&self, x: &T, span: &dyn Locatable) -> T
where
T: TypeFoldable<'tcx>,
{
let x = x.fold_with(&mut Resolver::new(self.fcx, span, self.body));
if cfg!(debug_assertions) && x.has_local_value() {
span_bug!(
span.to_span(self.fcx.tcx),
"writeback: `{:?}` is a local value",
x
);
}
x
}
}
trait Locatable {
fn to_span(&self, tcx: TyCtxt<'_>) -> Span;
}
impl Locatable for Span {
fn to_span(&self, _: TyCtxt<'_>) -> Span {
*self
}
}
impl Locatable for DefIndex {
fn to_span(&self, tcx: TyCtxt<'_>) -> Span {
let hir_id = tcx.hir().def_index_to_hir_id(*self);
tcx.hir().span(hir_id)
}
}
impl Locatable for hir::HirId {
fn to_span(&self, tcx: TyCtxt<'_>) -> Span {
tcx.hir().span(*self)
}
}
///////////////////////////////////////////////////////////////////////////
// The Resolver. This is the type folding engine that detects
// unresolved types and so forth.
struct Resolver<'cx, 'tcx> {
tcx: TyCtxt<'tcx>,
infcx: &'cx InferCtxt<'cx, 'tcx>,
span: &'cx dyn Locatable,
body: &'tcx hir::Body,
}
impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
fn new(
fcx: &'cx FnCtxt<'cx, 'tcx>,
span: &'cx dyn Locatable,
body: &'tcx hir::Body,
) -> Resolver<'cx, 'tcx> {
Resolver {
tcx: fcx.tcx,
infcx: fcx,
span,
body,
}
}
fn report_error(&self, t: Ty<'tcx>) {
if !self.tcx.sess.has_errors() {
self.infcx
.need_type_info_err(Some(self.body.id()), self.span.to_span(self.tcx), t)
.emit();
}
}
}
impl<'cx, 'tcx> TypeFolder<'tcx> for Resolver<'cx, 'tcx> {
fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
self.tcx
}
fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
match self.infcx.fully_resolve(&t) {
Ok(t) => t,
Err(_) => {
debug!(
"Resolver::fold_ty: input type `{:?}` not fully resolvable",
t
);
self.report_error(t);
self.tcx().types.err
}
}
}
// FIXME This should be carefully checked
// We could use `self.report_error` but it doesn't accept a ty::Region, right now.
fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
self.infcx.fully_resolve(&r).unwrap_or(self.tcx.lifetimes.re_static)
}
fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
match self.infcx.fully_resolve(&ct) {
Ok(ct) => ct,
Err(_) => {
debug!(
"Resolver::fold_const: input const `{:?}` not fully resolvable",
ct
);
// FIXME: we'd like to use `self.report_error`, but it doesn't yet
// accept a &'tcx ty::Const.
self.tcx().consts.err
}
}
}
}
///////////////////////////////////////////////////////////////////////////
// During type check, we store promises with the result of trait
// lookup rather than the actual results (because the results are not
// necessarily available immediately). These routines unwind the
// promises. It is expected that we will have already reported any
// errors that may be encountered, so if the promises store an error,
// a dummy result is returned.
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