typeck: check_expr_kind -> expr.rs
This commit is contained in:
Mazdak Farrokhzad
parent
9606f6fa64
commit
6cf4b3ac10
2 changed files with 708 additions and 673 deletions
706
src/librustc_typeck/check/expr.rs
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706
src/librustc_typeck/check/expr.rs
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//! Type checking expressions.
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//!
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//! See `mod.rs` for more context on type checking in general.
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use crate::check::BreakableCtxt;
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use crate::check::cast;
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use crate::check::coercion::CoerceMany;
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use crate::check::Diverges;
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use crate::check::FnCtxt;
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use crate::check::Expectation::{self, NoExpectation, ExpectHasType, ExpectCastableToType};
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use crate::check::fatally_break_rust;
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use crate::check::report_unexpected_variant_res;
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use crate::check::Needs;
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use crate::middle::lang_items;
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use crate::util::common::ErrorReported;
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use errors::Applicability;
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use syntax::ast;
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use syntax::symbol::sym;
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use rustc::hir;
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use rustc::hir::{ExprKind, QPath};
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use rustc::hir::def::{CtorKind, Res, DefKind};
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use rustc::infer;
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use rustc::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
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use rustc::mir::interpret::GlobalId;
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use rustc::ty;
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use rustc::ty::adjustment::{
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Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability,
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};
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use rustc::ty::Ty;
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use rustc::ty::TypeFoldable;
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use rustc::ty::subst::InternalSubsts;
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use rustc::traits::{self, ObligationCauseCode};
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impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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pub(super) fn check_expr_kind(
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&self,
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expr: &'tcx hir::Expr,
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expected: Expectation<'tcx>,
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needs: Needs,
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) -> Ty<'tcx> {
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debug!(
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"check_expr_kind(expr={:?}, expected={:?}, needs={:?})",
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expr,
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expected,
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needs,
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);
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let tcx = self.tcx;
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let id = expr.hir_id;
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match expr.node {
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ExprKind::Box(ref subexpr) => {
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let expected_inner = expected.to_option(self).map_or(NoExpectation, |ty| {
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match ty.sty {
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ty::Adt(def, _) if def.is_box()
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=> Expectation::rvalue_hint(self, ty.boxed_ty()),
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_ => NoExpectation
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}
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});
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let referent_ty = self.check_expr_with_expectation(subexpr, expected_inner);
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tcx.mk_box(referent_ty)
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}
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ExprKind::Lit(ref lit) => {
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self.check_lit(&lit, expected)
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}
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ExprKind::Binary(op, ref lhs, ref rhs) => {
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self.check_binop(expr, op, lhs, rhs)
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}
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ExprKind::AssignOp(op, ref lhs, ref rhs) => {
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self.check_binop_assign(expr, op, lhs, rhs)
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}
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ExprKind::Unary(unop, ref oprnd) => {
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let expected_inner = match unop {
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hir::UnNot | hir::UnNeg => {
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expected
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}
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hir::UnDeref => {
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NoExpectation
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}
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};
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let needs = match unop {
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hir::UnDeref => needs,
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_ => Needs::None
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};
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let mut oprnd_t = self.check_expr_with_expectation_and_needs(&oprnd,
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expected_inner,
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needs);
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if !oprnd_t.references_error() {
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oprnd_t = self.structurally_resolved_type(expr.span, oprnd_t);
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match unop {
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hir::UnDeref => {
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if let Some(mt) = oprnd_t.builtin_deref(true) {
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oprnd_t = mt.ty;
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} else if let Some(ok) = self.try_overloaded_deref(
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expr.span, oprnd_t, needs) {
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let method = self.register_infer_ok_obligations(ok);
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if let ty::Ref(region, _, mutbl) = method.sig.inputs()[0].sty {
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let mutbl = match mutbl {
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hir::MutImmutable => AutoBorrowMutability::Immutable,
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hir::MutMutable => AutoBorrowMutability::Mutable {
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// (It shouldn't actually matter for unary ops whether
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// we enable two-phase borrows or not, since a unary
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// op has no additional operands.)
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allow_two_phase_borrow: AllowTwoPhase::No,
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}
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};
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self.apply_adjustments(oprnd, vec![Adjustment {
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kind: Adjust::Borrow(AutoBorrow::Ref(region, mutbl)),
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target: method.sig.inputs()[0]
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}]);
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}
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oprnd_t = self.make_overloaded_place_return_type(method).ty;
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self.write_method_call(expr.hir_id, method);
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} else {
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let mut err = type_error_struct!(
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tcx.sess,
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expr.span,
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oprnd_t,
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E0614,
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"type `{}` cannot be dereferenced",
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oprnd_t,
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);
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let sp = tcx.sess.source_map().start_point(expr.span);
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if let Some(sp) = tcx.sess.parse_sess.ambiguous_block_expr_parse
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.borrow().get(&sp)
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{
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tcx.sess.parse_sess.expr_parentheses_needed(
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&mut err,
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*sp,
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None,
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);
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}
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err.emit();
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oprnd_t = tcx.types.err;
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}
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}
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hir::UnNot => {
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let result = self.check_user_unop(expr, oprnd_t, unop);
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// If it's builtin, we can reuse the type, this helps inference.
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if !(oprnd_t.is_integral() || oprnd_t.sty == ty::Bool) {
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oprnd_t = result;
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}
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}
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hir::UnNeg => {
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let result = self.check_user_unop(expr, oprnd_t, unop);
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// If it's builtin, we can reuse the type, this helps inference.
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if !oprnd_t.is_numeric() {
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oprnd_t = result;
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}
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}
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}
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}
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oprnd_t
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}
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ExprKind::AddrOf(mutbl, ref oprnd) => {
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let hint = expected.only_has_type(self).map_or(NoExpectation, |ty| {
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match ty.sty {
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ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => {
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if oprnd.is_place_expr() {
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// Places may legitimately have unsized types.
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// For example, dereferences of a fat pointer and
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// the last field of a struct can be unsized.
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ExpectHasType(ty)
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} else {
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Expectation::rvalue_hint(self, ty)
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}
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}
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_ => NoExpectation
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}
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});
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let needs = Needs::maybe_mut_place(mutbl);
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let ty = self.check_expr_with_expectation_and_needs(&oprnd, hint, needs);
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let tm = ty::TypeAndMut { ty: ty, mutbl: mutbl };
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if tm.ty.references_error() {
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tcx.types.err
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} else {
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// Note: at this point, we cannot say what the best lifetime
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// is to use for resulting pointer. We want to use the
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// shortest lifetime possible so as to avoid spurious borrowck
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// errors. Moreover, the longest lifetime will depend on the
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// precise details of the value whose address is being taken
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// (and how long it is valid), which we don't know yet until type
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// inference is complete.
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//
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// Therefore, here we simply generate a region variable. The
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// region inferencer will then select the ultimate value.
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// Finally, borrowck is charged with guaranteeing that the
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// value whose address was taken can actually be made to live
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// as long as it needs to live.
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let region = self.next_region_var(infer::AddrOfRegion(expr.span));
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tcx.mk_ref(region, tm)
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}
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}
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ExprKind::Path(ref qpath) => {
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let (res, opt_ty, segs) = self.resolve_ty_and_res_ufcs(qpath, expr.hir_id,
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expr.span);
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let ty = match res {
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Res::Err => {
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self.set_tainted_by_errors();
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tcx.types.err
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}
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Res::Def(DefKind::Ctor(_, CtorKind::Fictive), _) => {
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report_unexpected_variant_res(tcx, res, expr.span, qpath);
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tcx.types.err
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}
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_ => self.instantiate_value_path(segs, opt_ty, res, expr.span, id).0,
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};
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if let ty::FnDef(..) = ty.sty {
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let fn_sig = ty.fn_sig(tcx);
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if !tcx.features().unsized_locals {
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// We want to remove some Sized bounds from std functions,
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// but don't want to expose the removal to stable Rust.
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// i.e., we don't want to allow
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//
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// ```rust
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// drop as fn(str);
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// ```
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//
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// to work in stable even if the Sized bound on `drop` is relaxed.
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for i in 0..fn_sig.inputs().skip_binder().len() {
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// We just want to check sizedness, so instead of introducing
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// placeholder lifetimes with probing, we just replace higher lifetimes
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// with fresh vars.
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let input = self.replace_bound_vars_with_fresh_vars(
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expr.span,
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infer::LateBoundRegionConversionTime::FnCall,
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&fn_sig.input(i)).0;
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self.require_type_is_sized_deferred(input, expr.span,
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traits::SizedArgumentType);
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}
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}
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// Here we want to prevent struct constructors from returning unsized types.
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// There were two cases this happened: fn pointer coercion in stable
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// and usual function call in presense of unsized_locals.
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// Also, as we just want to check sizedness, instead of introducing
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// placeholder lifetimes with probing, we just replace higher lifetimes
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// with fresh vars.
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let output = self.replace_bound_vars_with_fresh_vars(
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expr.span,
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infer::LateBoundRegionConversionTime::FnCall,
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&fn_sig.output()).0;
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self.require_type_is_sized_deferred(output, expr.span, traits::SizedReturnType);
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}
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// We always require that the type provided as the value for
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// a type parameter outlives the moment of instantiation.
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let substs = self.tables.borrow().node_substs(expr.hir_id);
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self.add_wf_bounds(substs, expr);
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ty
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}
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ExprKind::InlineAsm(_, ref outputs, ref inputs) => {
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for expr in outputs.iter().chain(inputs.iter()) {
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self.check_expr(expr);
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}
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tcx.mk_unit()
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}
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ExprKind::Break(destination, ref expr_opt) => {
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if let Ok(target_id) = destination.target_id {
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let (e_ty, cause);
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if let Some(ref e) = *expr_opt {
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// If this is a break with a value, we need to type-check
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// the expression. Get an expected type from the loop context.
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let opt_coerce_to = {
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let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
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enclosing_breakables.find_breakable(target_id)
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.coerce
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.as_ref()
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.map(|coerce| coerce.expected_ty())
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};
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// If the loop context is not a `loop { }`, then break with
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// a value is illegal, and `opt_coerce_to` will be `None`.
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// Just set expectation to error in that case.
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let coerce_to = opt_coerce_to.unwrap_or(tcx.types.err);
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// Recurse without `enclosing_breakables` borrowed.
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e_ty = self.check_expr_with_hint(e, coerce_to);
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cause = self.misc(e.span);
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} else {
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// Otherwise, this is a break *without* a value. That's
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// always legal, and is equivalent to `break ()`.
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e_ty = tcx.mk_unit();
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cause = self.misc(expr.span);
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}
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// Now that we have type-checked `expr_opt`, borrow
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// the `enclosing_loops` field and let's coerce the
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// type of `expr_opt` into what is expected.
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let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
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let ctxt = enclosing_breakables.find_breakable(target_id);
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if let Some(ref mut coerce) = ctxt.coerce {
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if let Some(ref e) = *expr_opt {
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coerce.coerce(self, &cause, e, e_ty);
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} else {
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assert!(e_ty.is_unit());
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coerce.coerce_forced_unit(self, &cause, &mut |_| (), true);
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}
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} else {
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// If `ctxt.coerce` is `None`, we can just ignore
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// the type of the expresison. This is because
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// either this was a break *without* a value, in
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// which case it is always a legal type (`()`), or
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// else an error would have been flagged by the
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// `loops` pass for using break with an expression
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// where you are not supposed to.
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assert!(expr_opt.is_none() || self.tcx.sess.err_count() > 0);
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}
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ctxt.may_break = true;
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// the type of a `break` is always `!`, since it diverges
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tcx.types.never
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} else {
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// Otherwise, we failed to find the enclosing loop;
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// this can only happen if the `break` was not
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// inside a loop at all, which is caught by the
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// loop-checking pass.
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if self.tcx.sess.err_count() == 0 {
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self.tcx.sess.delay_span_bug(expr.span,
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"break was outside loop, but no error was emitted");
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}
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// We still need to assign a type to the inner expression to
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// prevent the ICE in #43162.
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if let Some(ref e) = *expr_opt {
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self.check_expr_with_hint(e, tcx.types.err);
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// ... except when we try to 'break rust;'.
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// ICE this expression in particular (see #43162).
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if let ExprKind::Path(QPath::Resolved(_, ref path)) = e.node {
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if path.segments.len() == 1 &&
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path.segments[0].ident.name == sym::rust {
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fatally_break_rust(self.tcx.sess);
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}
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}
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}
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// There was an error; make type-check fail.
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tcx.types.err
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}
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}
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ExprKind::Continue(destination) => {
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if destination.target_id.is_ok() {
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tcx.types.never
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} else {
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// There was an error; make type-check fail.
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tcx.types.err
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}
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}
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ExprKind::Ret(ref expr_opt) => {
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if self.ret_coercion.is_none() {
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struct_span_err!(self.tcx.sess, expr.span, E0572,
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"return statement outside of function body").emit();
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} else if let Some(ref e) = *expr_opt {
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if self.ret_coercion_span.borrow().is_none() {
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*self.ret_coercion_span.borrow_mut() = Some(e.span);
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}
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self.check_return_expr(e);
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} else {
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let mut coercion = self.ret_coercion.as_ref().unwrap().borrow_mut();
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if self.ret_coercion_span.borrow().is_none() {
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*self.ret_coercion_span.borrow_mut() = Some(expr.span);
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}
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let cause = self.cause(expr.span, ObligationCauseCode::ReturnNoExpression);
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if let Some((fn_decl, _)) = self.get_fn_decl(expr.hir_id) {
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coercion.coerce_forced_unit(
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self,
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&cause,
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&mut |db| {
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db.span_label(
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fn_decl.output.span(),
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format!(
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"expected `{}` because of this return type",
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fn_decl.output,
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),
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);
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},
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true,
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);
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} else {
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coercion.coerce_forced_unit(self, &cause, &mut |_| (), true);
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}
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}
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tcx.types.never
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}
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ExprKind::Assign(ref lhs, ref rhs) => {
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self.check_assign(expr, expected, lhs, rhs)
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}
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ExprKind::While(ref cond, ref body, _) => {
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let ctxt = BreakableCtxt {
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// cannot use break with a value from a while loop
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coerce: None,
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may_break: false, // Will get updated if/when we find a `break`.
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};
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let (ctxt, ()) = self.with_breakable_ctxt(expr.hir_id, ctxt, || {
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self.check_expr_has_type_or_error(&cond, tcx.types.bool);
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let cond_diverging = self.diverges.get();
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self.check_block_no_value(&body);
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// We may never reach the body so it diverging means nothing.
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self.diverges.set(cond_diverging);
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});
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if ctxt.may_break {
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// No way to know whether it's diverging because
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// of a `break` or an outer `break` or `return`.
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self.diverges.set(Diverges::Maybe);
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}
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self.tcx.mk_unit()
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}
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ExprKind::Loop(ref body, _, source) => {
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let coerce = match source {
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// you can only use break with a value from a normal `loop { }`
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hir::LoopSource::Loop => {
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let coerce_to = expected.coercion_target_type(self, body.span);
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Some(CoerceMany::new(coerce_to))
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}
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hir::LoopSource::WhileLet |
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hir::LoopSource::ForLoop => {
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None
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}
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};
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let ctxt = BreakableCtxt {
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coerce,
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may_break: false, // Will get updated if/when we find a `break`.
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};
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let (ctxt, ()) = self.with_breakable_ctxt(expr.hir_id, ctxt, || {
|
||||
self.check_block_no_value(&body);
|
||||
});
|
||||
|
||||
if ctxt.may_break {
|
||||
// No way to know whether it's diverging because
|
||||
// of a `break` or an outer `break` or `return`.
|
||||
self.diverges.set(Diverges::Maybe);
|
||||
}
|
||||
|
||||
// If we permit break with a value, then result type is
|
||||
// the LUB of the breaks (possibly ! if none); else, it
|
||||
// is nil. This makes sense because infinite loops
|
||||
// (which would have type !) are only possible iff we
|
||||
// permit break with a value [1].
|
||||
if ctxt.coerce.is_none() && !ctxt.may_break {
|
||||
// [1]
|
||||
self.tcx.sess.delay_span_bug(body.span, "no coercion, but loop may not break");
|
||||
}
|
||||
ctxt.coerce.map(|c| c.complete(self)).unwrap_or_else(|| self.tcx.mk_unit())
|
||||
}
|
||||
ExprKind::Match(ref discrim, ref arms, match_src) => {
|
||||
self.check_match(expr, &discrim, arms, expected, match_src)
|
||||
}
|
||||
ExprKind::Closure(capture, ref decl, body_id, _, gen) => {
|
||||
self.check_expr_closure(expr, capture, &decl, body_id, gen, expected)
|
||||
}
|
||||
ExprKind::Block(ref body, _) => {
|
||||
self.check_block_with_expected(&body, expected)
|
||||
}
|
||||
ExprKind::Call(ref callee, ref args) => {
|
||||
self.check_call(expr, &callee, args, expected)
|
||||
}
|
||||
ExprKind::MethodCall(ref segment, span, ref args) => {
|
||||
self.check_method_call(expr, segment, span, args, expected, needs)
|
||||
}
|
||||
ExprKind::Cast(ref e, ref t) => {
|
||||
// Find the type of `e`. Supply hints based on the type we are casting to,
|
||||
// if appropriate.
|
||||
let t_cast = self.to_ty_saving_user_provided_ty(t);
|
||||
let t_cast = self.resolve_vars_if_possible(&t_cast);
|
||||
let t_expr = self.check_expr_with_expectation(e, ExpectCastableToType(t_cast));
|
||||
let t_cast = self.resolve_vars_if_possible(&t_cast);
|
||||
|
||||
// Eagerly check for some obvious errors.
|
||||
if t_expr.references_error() || t_cast.references_error() {
|
||||
tcx.types.err
|
||||
} else {
|
||||
// Defer other checks until we're done type checking.
|
||||
let mut deferred_cast_checks = self.deferred_cast_checks.borrow_mut();
|
||||
match cast::CastCheck::new(self, e, t_expr, t_cast, t.span, expr.span) {
|
||||
Ok(cast_check) => {
|
||||
deferred_cast_checks.push(cast_check);
|
||||
t_cast
|
||||
}
|
||||
Err(ErrorReported) => {
|
||||
tcx.types.err
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
ExprKind::Type(ref e, ref t) => {
|
||||
let ty = self.to_ty_saving_user_provided_ty(&t);
|
||||
self.check_expr_eq_type(&e, ty);
|
||||
ty
|
||||
}
|
||||
ExprKind::DropTemps(ref e) => {
|
||||
self.check_expr_with_expectation(e, expected)
|
||||
}
|
||||
ExprKind::Array(ref args) => {
|
||||
let uty = expected.to_option(self).and_then(|uty| {
|
||||
match uty.sty {
|
||||
ty::Array(ty, _) | ty::Slice(ty) => Some(ty),
|
||||
_ => None
|
||||
}
|
||||
});
|
||||
|
||||
let element_ty = if !args.is_empty() {
|
||||
let coerce_to = uty.unwrap_or_else(|| {
|
||||
self.next_ty_var(TypeVariableOrigin {
|
||||
kind: TypeVariableOriginKind::TypeInference,
|
||||
span: expr.span,
|
||||
})
|
||||
});
|
||||
let mut coerce = CoerceMany::with_coercion_sites(coerce_to, args);
|
||||
assert_eq!(self.diverges.get(), Diverges::Maybe);
|
||||
for e in args {
|
||||
let e_ty = self.check_expr_with_hint(e, coerce_to);
|
||||
let cause = self.misc(e.span);
|
||||
coerce.coerce(self, &cause, e, e_ty);
|
||||
}
|
||||
coerce.complete(self)
|
||||
} else {
|
||||
self.next_ty_var(TypeVariableOrigin {
|
||||
kind: TypeVariableOriginKind::TypeInference,
|
||||
span: expr.span,
|
||||
})
|
||||
};
|
||||
tcx.mk_array(element_ty, args.len() as u64)
|
||||
}
|
||||
ExprKind::Repeat(ref element, ref count) => {
|
||||
let count_def_id = tcx.hir().local_def_id_from_hir_id(count.hir_id);
|
||||
let count = if self.const_param_def_id(count).is_some() {
|
||||
Ok(self.to_const(count, self.tcx.type_of(count_def_id)))
|
||||
} else {
|
||||
let param_env = ty::ParamEnv::empty();
|
||||
let substs = InternalSubsts::identity_for_item(tcx.global_tcx(), count_def_id);
|
||||
let instance = ty::Instance::resolve(
|
||||
tcx.global_tcx(),
|
||||
param_env,
|
||||
count_def_id,
|
||||
substs,
|
||||
).unwrap();
|
||||
let global_id = GlobalId {
|
||||
instance,
|
||||
promoted: None
|
||||
};
|
||||
|
||||
tcx.const_eval(param_env.and(global_id))
|
||||
};
|
||||
|
||||
let uty = match expected {
|
||||
ExpectHasType(uty) => {
|
||||
match uty.sty {
|
||||
ty::Array(ty, _) | ty::Slice(ty) => Some(ty),
|
||||
_ => None
|
||||
}
|
||||
}
|
||||
_ => None
|
||||
};
|
||||
|
||||
let (element_ty, t) = match uty {
|
||||
Some(uty) => {
|
||||
self.check_expr_coercable_to_type(&element, uty);
|
||||
(uty, uty)
|
||||
}
|
||||
None => {
|
||||
let ty = self.next_ty_var(TypeVariableOrigin {
|
||||
kind: TypeVariableOriginKind::MiscVariable,
|
||||
span: element.span,
|
||||
});
|
||||
let element_ty = self.check_expr_has_type_or_error(&element, ty);
|
||||
(element_ty, ty)
|
||||
}
|
||||
};
|
||||
|
||||
if let Ok(count) = count {
|
||||
let zero_or_one = count.assert_usize(tcx).map_or(false, |count| count <= 1);
|
||||
if !zero_or_one {
|
||||
// For [foo, ..n] where n > 1, `foo` must have
|
||||
// Copy type:
|
||||
let lang_item = self.tcx.require_lang_item(lang_items::CopyTraitLangItem);
|
||||
self.require_type_meets(t, expr.span, traits::RepeatVec, lang_item);
|
||||
}
|
||||
}
|
||||
|
||||
if element_ty.references_error() {
|
||||
tcx.types.err
|
||||
} else if let Ok(count) = count {
|
||||
tcx.mk_ty(ty::Array(t, count))
|
||||
} else {
|
||||
tcx.types.err
|
||||
}
|
||||
}
|
||||
ExprKind::Tup(ref elts) => {
|
||||
let flds = expected.only_has_type(self).and_then(|ty| {
|
||||
let ty = self.resolve_type_vars_with_obligations(ty);
|
||||
match ty.sty {
|
||||
ty::Tuple(ref flds) => Some(&flds[..]),
|
||||
_ => None
|
||||
}
|
||||
});
|
||||
|
||||
let elt_ts_iter = elts.iter().enumerate().map(|(i, e)| {
|
||||
let t = match flds {
|
||||
Some(ref fs) if i < fs.len() => {
|
||||
let ety = fs[i].expect_ty();
|
||||
self.check_expr_coercable_to_type(&e, ety);
|
||||
ety
|
||||
}
|
||||
_ => {
|
||||
self.check_expr_with_expectation(&e, NoExpectation)
|
||||
}
|
||||
};
|
||||
t
|
||||
});
|
||||
let tuple = tcx.mk_tup(elt_ts_iter);
|
||||
if tuple.references_error() {
|
||||
tcx.types.err
|
||||
} else {
|
||||
self.require_type_is_sized(tuple, expr.span, traits::TupleInitializerSized);
|
||||
tuple
|
||||
}
|
||||
}
|
||||
ExprKind::Struct(ref qpath, ref fields, ref base_expr) => {
|
||||
self.check_expr_struct(expr, expected, qpath, fields, base_expr)
|
||||
}
|
||||
ExprKind::Field(ref base, field) => {
|
||||
self.check_field(expr, needs, &base, field)
|
||||
}
|
||||
ExprKind::Index(ref base, ref idx) => {
|
||||
let base_t = self.check_expr_with_needs(&base, needs);
|
||||
let idx_t = self.check_expr(&idx);
|
||||
|
||||
if base_t.references_error() {
|
||||
base_t
|
||||
} else if idx_t.references_error() {
|
||||
idx_t
|
||||
} else {
|
||||
let base_t = self.structurally_resolved_type(base.span, base_t);
|
||||
match self.lookup_indexing(expr, base, base_t, idx_t, needs) {
|
||||
Some((index_ty, element_ty)) => {
|
||||
// two-phase not needed because index_ty is never mutable
|
||||
self.demand_coerce(idx, idx_t, index_ty, AllowTwoPhase::No);
|
||||
element_ty
|
||||
}
|
||||
None => {
|
||||
let mut err =
|
||||
type_error_struct!(tcx.sess, expr.span, base_t, E0608,
|
||||
"cannot index into a value of type `{}`",
|
||||
base_t);
|
||||
// Try to give some advice about indexing tuples.
|
||||
if let ty::Tuple(..) = base_t.sty {
|
||||
let mut needs_note = true;
|
||||
// If the index is an integer, we can show the actual
|
||||
// fixed expression:
|
||||
if let ExprKind::Lit(ref lit) = idx.node {
|
||||
if let ast::LitKind::Int(i,
|
||||
ast::LitIntType::Unsuffixed) = lit.node {
|
||||
let snip = tcx.sess.source_map().span_to_snippet(base.span);
|
||||
if let Ok(snip) = snip {
|
||||
err.span_suggestion(
|
||||
expr.span,
|
||||
"to access tuple elements, use",
|
||||
format!("{}.{}", snip, i),
|
||||
Applicability::MachineApplicable,
|
||||
);
|
||||
needs_note = false;
|
||||
}
|
||||
}
|
||||
}
|
||||
if needs_note {
|
||||
err.help("to access tuple elements, use tuple indexing \
|
||||
syntax (e.g., `tuple.0`)");
|
||||
}
|
||||
}
|
||||
err.emit();
|
||||
self.tcx.types.err
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
ExprKind::Yield(ref value) => {
|
||||
match self.yield_ty {
|
||||
Some(ty) => {
|
||||
self.check_expr_coercable_to_type(&value, ty);
|
||||
}
|
||||
None => {
|
||||
struct_span_err!(self.tcx.sess, expr.span, E0627,
|
||||
"yield statement outside of generator literal").emit();
|
||||
}
|
||||
}
|
||||
tcx.mk_unit()
|
||||
}
|
||||
hir::ExprKind::Err => {
|
||||
tcx.types.err
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
@ -74,6 +74,7 @@ pub mod writeback;
|
|||
mod regionck;
|
||||
pub mod coercion;
|
||||
pub mod demand;
|
||||
mod expr;
|
||||
pub mod method;
|
||||
mod upvar;
|
||||
mod wfcheck;
|
||||
|
|
@ -88,7 +89,7 @@ mod op;
|
|||
use crate::astconv::{AstConv, PathSeg};
|
||||
use errors::{Applicability, DiagnosticBuilder, DiagnosticId};
|
||||
use rustc::hir::{self, ExprKind, GenericArg, ItemKind, Node, PatKind, QPath};
|
||||
use rustc::hir::def::{CtorOf, CtorKind, Res, DefKind};
|
||||
use rustc::hir::def::{CtorOf, Res, DefKind};
|
||||
use rustc::hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
|
||||
use rustc::hir::intravisit::{self, Visitor, NestedVisitorMap};
|
||||
use rustc::hir::itemlikevisit::ItemLikeVisitor;
|
||||
|
|
@ -3923,7 +3924,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
|
|||
adt_ty
|
||||
}
|
||||
|
||||
|
||||
/// Invariant:
|
||||
/// If an expression has any sub-expressions that result in a type error,
|
||||
/// inspecting that expression's type with `ty.references_error()` will return
|
||||
|
|
@ -3983,677 +3983,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
|
|||
ty
|
||||
}
|
||||
|
||||
fn check_expr_kind(
|
||||
&self,
|
||||
expr: &'tcx hir::Expr,
|
||||
expected: Expectation<'tcx>,
|
||||
needs: Needs,
|
||||
) -> Ty<'tcx> {
|
||||
debug!(
|
||||
"check_expr_kind(expr={:?}, expected={:?}, needs={:?})",
|
||||
expr,
|
||||
expected,
|
||||
needs,
|
||||
);
|
||||
|
||||
let tcx = self.tcx;
|
||||
let id = expr.hir_id;
|
||||
match expr.node {
|
||||
ExprKind::Box(ref subexpr) => {
|
||||
let expected_inner = expected.to_option(self).map_or(NoExpectation, |ty| {
|
||||
match ty.sty {
|
||||
ty::Adt(def, _) if def.is_box()
|
||||
=> Expectation::rvalue_hint(self, ty.boxed_ty()),
|
||||
_ => NoExpectation
|
||||
}
|
||||
});
|
||||
let referent_ty = self.check_expr_with_expectation(subexpr, expected_inner);
|
||||
tcx.mk_box(referent_ty)
|
||||
}
|
||||
|
||||
ExprKind::Lit(ref lit) => {
|
||||
self.check_lit(&lit, expected)
|
||||
}
|
||||
ExprKind::Binary(op, ref lhs, ref rhs) => {
|
||||
self.check_binop(expr, op, lhs, rhs)
|
||||
}
|
||||
ExprKind::AssignOp(op, ref lhs, ref rhs) => {
|
||||
self.check_binop_assign(expr, op, lhs, rhs)
|
||||
}
|
||||
ExprKind::Unary(unop, ref oprnd) => {
|
||||
let expected_inner = match unop {
|
||||
hir::UnNot | hir::UnNeg => {
|
||||
expected
|
||||
}
|
||||
hir::UnDeref => {
|
||||
NoExpectation
|
||||
}
|
||||
};
|
||||
let needs = match unop {
|
||||
hir::UnDeref => needs,
|
||||
_ => Needs::None
|
||||
};
|
||||
let mut oprnd_t = self.check_expr_with_expectation_and_needs(&oprnd,
|
||||
expected_inner,
|
||||
needs);
|
||||
|
||||
if !oprnd_t.references_error() {
|
||||
oprnd_t = self.structurally_resolved_type(expr.span, oprnd_t);
|
||||
match unop {
|
||||
hir::UnDeref => {
|
||||
if let Some(mt) = oprnd_t.builtin_deref(true) {
|
||||
oprnd_t = mt.ty;
|
||||
} else if let Some(ok) = self.try_overloaded_deref(
|
||||
expr.span, oprnd_t, needs) {
|
||||
let method = self.register_infer_ok_obligations(ok);
|
||||
if let ty::Ref(region, _, mutbl) = method.sig.inputs()[0].sty {
|
||||
let mutbl = match mutbl {
|
||||
hir::MutImmutable => AutoBorrowMutability::Immutable,
|
||||
hir::MutMutable => AutoBorrowMutability::Mutable {
|
||||
// (It shouldn't actually matter for unary ops whether
|
||||
// we enable two-phase borrows or not, since a unary
|
||||
// op has no additional operands.)
|
||||
allow_two_phase_borrow: AllowTwoPhase::No,
|
||||
}
|
||||
};
|
||||
self.apply_adjustments(oprnd, vec![Adjustment {
|
||||
kind: Adjust::Borrow(AutoBorrow::Ref(region, mutbl)),
|
||||
target: method.sig.inputs()[0]
|
||||
}]);
|
||||
}
|
||||
oprnd_t = self.make_overloaded_place_return_type(method).ty;
|
||||
self.write_method_call(expr.hir_id, method);
|
||||
} else {
|
||||
let mut err = type_error_struct!(
|
||||
tcx.sess,
|
||||
expr.span,
|
||||
oprnd_t,
|
||||
E0614,
|
||||
"type `{}` cannot be dereferenced",
|
||||
oprnd_t,
|
||||
);
|
||||
let sp = tcx.sess.source_map().start_point(expr.span);
|
||||
if let Some(sp) = tcx.sess.parse_sess.ambiguous_block_expr_parse
|
||||
.borrow().get(&sp)
|
||||
{
|
||||
tcx.sess.parse_sess.expr_parentheses_needed(
|
||||
&mut err,
|
||||
*sp,
|
||||
None,
|
||||
);
|
||||
}
|
||||
err.emit();
|
||||
oprnd_t = tcx.types.err;
|
||||
}
|
||||
}
|
||||
hir::UnNot => {
|
||||
let result = self.check_user_unop(expr, oprnd_t, unop);
|
||||
// If it's builtin, we can reuse the type, this helps inference.
|
||||
if !(oprnd_t.is_integral() || oprnd_t.sty == ty::Bool) {
|
||||
oprnd_t = result;
|
||||
}
|
||||
}
|
||||
hir::UnNeg => {
|
||||
let result = self.check_user_unop(expr, oprnd_t, unop);
|
||||
// If it's builtin, we can reuse the type, this helps inference.
|
||||
if !oprnd_t.is_numeric() {
|
||||
oprnd_t = result;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
oprnd_t
|
||||
}
|
||||
ExprKind::AddrOf(mutbl, ref oprnd) => {
|
||||
let hint = expected.only_has_type(self).map_or(NoExpectation, |ty| {
|
||||
match ty.sty {
|
||||
ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => {
|
||||
if oprnd.is_place_expr() {
|
||||
// Places may legitimately have unsized types.
|
||||
// For example, dereferences of a fat pointer and
|
||||
// the last field of a struct can be unsized.
|
||||
ExpectHasType(ty)
|
||||
} else {
|
||||
Expectation::rvalue_hint(self, ty)
|
||||
}
|
||||
}
|
||||
_ => NoExpectation
|
||||
}
|
||||
});
|
||||
let needs = Needs::maybe_mut_place(mutbl);
|
||||
let ty = self.check_expr_with_expectation_and_needs(&oprnd, hint, needs);
|
||||
|
||||
let tm = ty::TypeAndMut { ty: ty, mutbl: mutbl };
|
||||
if tm.ty.references_error() {
|
||||
tcx.types.err
|
||||
} else {
|
||||
// Note: at this point, we cannot say what the best lifetime
|
||||
// is to use for resulting pointer. We want to use the
|
||||
// shortest lifetime possible so as to avoid spurious borrowck
|
||||
// errors. Moreover, the longest lifetime will depend on the
|
||||
// precise details of the value whose address is being taken
|
||||
// (and how long it is valid), which we don't know yet until type
|
||||
// inference is complete.
|
||||
//
|
||||
// Therefore, here we simply generate a region variable. The
|
||||
// region inferencer will then select the ultimate value.
|
||||
// Finally, borrowck is charged with guaranteeing that the
|
||||
// value whose address was taken can actually be made to live
|
||||
// as long as it needs to live.
|
||||
let region = self.next_region_var(infer::AddrOfRegion(expr.span));
|
||||
tcx.mk_ref(region, tm)
|
||||
}
|
||||
}
|
||||
ExprKind::Path(ref qpath) => {
|
||||
let (res, opt_ty, segs) = self.resolve_ty_and_res_ufcs(qpath, expr.hir_id,
|
||||
expr.span);
|
||||
let ty = match res {
|
||||
Res::Err => {
|
||||
self.set_tainted_by_errors();
|
||||
tcx.types.err
|
||||
}
|
||||
Res::Def(DefKind::Ctor(_, CtorKind::Fictive), _) => {
|
||||
report_unexpected_variant_res(tcx, res, expr.span, qpath);
|
||||
tcx.types.err
|
||||
}
|
||||
_ => self.instantiate_value_path(segs, opt_ty, res, expr.span, id).0,
|
||||
};
|
||||
|
||||
if let ty::FnDef(..) = ty.sty {
|
||||
let fn_sig = ty.fn_sig(tcx);
|
||||
if !tcx.features().unsized_locals {
|
||||
// We want to remove some Sized bounds from std functions,
|
||||
// but don't want to expose the removal to stable Rust.
|
||||
// i.e., we don't want to allow
|
||||
//
|
||||
// ```rust
|
||||
// drop as fn(str);
|
||||
// ```
|
||||
//
|
||||
// to work in stable even if the Sized bound on `drop` is relaxed.
|
||||
for i in 0..fn_sig.inputs().skip_binder().len() {
|
||||
// We just want to check sizedness, so instead of introducing
|
||||
// placeholder lifetimes with probing, we just replace higher lifetimes
|
||||
// with fresh vars.
|
||||
let input = self.replace_bound_vars_with_fresh_vars(
|
||||
expr.span,
|
||||
infer::LateBoundRegionConversionTime::FnCall,
|
||||
&fn_sig.input(i)).0;
|
||||
self.require_type_is_sized_deferred(input, expr.span,
|
||||
traits::SizedArgumentType);
|
||||
}
|
||||
}
|
||||
// Here we want to prevent struct constructors from returning unsized types.
|
||||
// There were two cases this happened: fn pointer coercion in stable
|
||||
// and usual function call in presense of unsized_locals.
|
||||
// Also, as we just want to check sizedness, instead of introducing
|
||||
// placeholder lifetimes with probing, we just replace higher lifetimes
|
||||
// with fresh vars.
|
||||
let output = self.replace_bound_vars_with_fresh_vars(
|
||||
expr.span,
|
||||
infer::LateBoundRegionConversionTime::FnCall,
|
||||
&fn_sig.output()).0;
|
||||
self.require_type_is_sized_deferred(output, expr.span, traits::SizedReturnType);
|
||||
}
|
||||
|
||||
// We always require that the type provided as the value for
|
||||
// a type parameter outlives the moment of instantiation.
|
||||
let substs = self.tables.borrow().node_substs(expr.hir_id);
|
||||
self.add_wf_bounds(substs, expr);
|
||||
|
||||
ty
|
||||
}
|
||||
ExprKind::InlineAsm(_, ref outputs, ref inputs) => {
|
||||
for expr in outputs.iter().chain(inputs.iter()) {
|
||||
self.check_expr(expr);
|
||||
}
|
||||
tcx.mk_unit()
|
||||
}
|
||||
ExprKind::Break(destination, ref expr_opt) => {
|
||||
if let Ok(target_id) = destination.target_id {
|
||||
let (e_ty, cause);
|
||||
if let Some(ref e) = *expr_opt {
|
||||
// If this is a break with a value, we need to type-check
|
||||
// the expression. Get an expected type from the loop context.
|
||||
let opt_coerce_to = {
|
||||
let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
|
||||
enclosing_breakables.find_breakable(target_id)
|
||||
.coerce
|
||||
.as_ref()
|
||||
.map(|coerce| coerce.expected_ty())
|
||||
};
|
||||
|
||||
// If the loop context is not a `loop { }`, then break with
|
||||
// a value is illegal, and `opt_coerce_to` will be `None`.
|
||||
// Just set expectation to error in that case.
|
||||
let coerce_to = opt_coerce_to.unwrap_or(tcx.types.err);
|
||||
|
||||
// Recurse without `enclosing_breakables` borrowed.
|
||||
e_ty = self.check_expr_with_hint(e, coerce_to);
|
||||
cause = self.misc(e.span);
|
||||
} else {
|
||||
// Otherwise, this is a break *without* a value. That's
|
||||
// always legal, and is equivalent to `break ()`.
|
||||
e_ty = tcx.mk_unit();
|
||||
cause = self.misc(expr.span);
|
||||
}
|
||||
|
||||
// Now that we have type-checked `expr_opt`, borrow
|
||||
// the `enclosing_loops` field and let's coerce the
|
||||
// type of `expr_opt` into what is expected.
|
||||
let mut enclosing_breakables = self.enclosing_breakables.borrow_mut();
|
||||
let ctxt = enclosing_breakables.find_breakable(target_id);
|
||||
if let Some(ref mut coerce) = ctxt.coerce {
|
||||
if let Some(ref e) = *expr_opt {
|
||||
coerce.coerce(self, &cause, e, e_ty);
|
||||
} else {
|
||||
assert!(e_ty.is_unit());
|
||||
coerce.coerce_forced_unit(self, &cause, &mut |_| (), true);
|
||||
}
|
||||
} else {
|
||||
// If `ctxt.coerce` is `None`, we can just ignore
|
||||
// the type of the expresison. This is because
|
||||
// either this was a break *without* a value, in
|
||||
// which case it is always a legal type (`()`), or
|
||||
// else an error would have been flagged by the
|
||||
// `loops` pass for using break with an expression
|
||||
// where you are not supposed to.
|
||||
assert!(expr_opt.is_none() || self.tcx.sess.err_count() > 0);
|
||||
}
|
||||
|
||||
ctxt.may_break = true;
|
||||
|
||||
// the type of a `break` is always `!`, since it diverges
|
||||
tcx.types.never
|
||||
} else {
|
||||
// Otherwise, we failed to find the enclosing loop;
|
||||
// this can only happen if the `break` was not
|
||||
// inside a loop at all, which is caught by the
|
||||
// loop-checking pass.
|
||||
if self.tcx.sess.err_count() == 0 {
|
||||
self.tcx.sess.delay_span_bug(expr.span,
|
||||
"break was outside loop, but no error was emitted");
|
||||
}
|
||||
|
||||
// We still need to assign a type to the inner expression to
|
||||
// prevent the ICE in #43162.
|
||||
if let Some(ref e) = *expr_opt {
|
||||
self.check_expr_with_hint(e, tcx.types.err);
|
||||
|
||||
// ... except when we try to 'break rust;'.
|
||||
// ICE this expression in particular (see #43162).
|
||||
if let ExprKind::Path(QPath::Resolved(_, ref path)) = e.node {
|
||||
if path.segments.len() == 1 &&
|
||||
path.segments[0].ident.name == sym::rust {
|
||||
fatally_break_rust(self.tcx.sess);
|
||||
}
|
||||
}
|
||||
}
|
||||
// There was an error; make type-check fail.
|
||||
tcx.types.err
|
||||
}
|
||||
|
||||
}
|
||||
ExprKind::Continue(destination) => {
|
||||
if destination.target_id.is_ok() {
|
||||
tcx.types.never
|
||||
} else {
|
||||
// There was an error; make type-check fail.
|
||||
tcx.types.err
|
||||
}
|
||||
}
|
||||
ExprKind::Ret(ref expr_opt) => {
|
||||
if self.ret_coercion.is_none() {
|
||||
struct_span_err!(self.tcx.sess, expr.span, E0572,
|
||||
"return statement outside of function body").emit();
|
||||
} else if let Some(ref e) = *expr_opt {
|
||||
if self.ret_coercion_span.borrow().is_none() {
|
||||
*self.ret_coercion_span.borrow_mut() = Some(e.span);
|
||||
}
|
||||
self.check_return_expr(e);
|
||||
} else {
|
||||
let mut coercion = self.ret_coercion.as_ref().unwrap().borrow_mut();
|
||||
if self.ret_coercion_span.borrow().is_none() {
|
||||
*self.ret_coercion_span.borrow_mut() = Some(expr.span);
|
||||
}
|
||||
let cause = self.cause(expr.span, ObligationCauseCode::ReturnNoExpression);
|
||||
if let Some((fn_decl, _)) = self.get_fn_decl(expr.hir_id) {
|
||||
coercion.coerce_forced_unit(
|
||||
self,
|
||||
&cause,
|
||||
&mut |db| {
|
||||
db.span_label(
|
||||
fn_decl.output.span(),
|
||||
format!(
|
||||
"expected `{}` because of this return type",
|
||||
fn_decl.output,
|
||||
),
|
||||
);
|
||||
},
|
||||
true,
|
||||
);
|
||||
} else {
|
||||
coercion.coerce_forced_unit(self, &cause, &mut |_| (), true);
|
||||
}
|
||||
}
|
||||
tcx.types.never
|
||||
}
|
||||
ExprKind::Assign(ref lhs, ref rhs) => {
|
||||
self.check_assign(expr, expected, lhs, rhs)
|
||||
}
|
||||
ExprKind::While(ref cond, ref body, _) => {
|
||||
let ctxt = BreakableCtxt {
|
||||
// cannot use break with a value from a while loop
|
||||
coerce: None,
|
||||
may_break: false, // Will get updated if/when we find a `break`.
|
||||
};
|
||||
|
||||
let (ctxt, ()) = self.with_breakable_ctxt(expr.hir_id, ctxt, || {
|
||||
self.check_expr_has_type_or_error(&cond, tcx.types.bool);
|
||||
let cond_diverging = self.diverges.get();
|
||||
self.check_block_no_value(&body);
|
||||
|
||||
// We may never reach the body so it diverging means nothing.
|
||||
self.diverges.set(cond_diverging);
|
||||
});
|
||||
|
||||
if ctxt.may_break {
|
||||
// No way to know whether it's diverging because
|
||||
// of a `break` or an outer `break` or `return`.
|
||||
self.diverges.set(Diverges::Maybe);
|
||||
}
|
||||
|
||||
self.tcx.mk_unit()
|
||||
}
|
||||
ExprKind::Loop(ref body, _, source) => {
|
||||
let coerce = match source {
|
||||
// you can only use break with a value from a normal `loop { }`
|
||||
hir::LoopSource::Loop => {
|
||||
let coerce_to = expected.coercion_target_type(self, body.span);
|
||||
Some(CoerceMany::new(coerce_to))
|
||||
}
|
||||
|
||||
hir::LoopSource::WhileLet |
|
||||
hir::LoopSource::ForLoop => {
|
||||
None
|
||||
}
|
||||
};
|
||||
|
||||
let ctxt = BreakableCtxt {
|
||||
coerce,
|
||||
may_break: false, // Will get updated if/when we find a `break`.
|
||||
};
|
||||
|
||||
let (ctxt, ()) = self.with_breakable_ctxt(expr.hir_id, ctxt, || {
|
||||
self.check_block_no_value(&body);
|
||||
});
|
||||
|
||||
if ctxt.may_break {
|
||||
// No way to know whether it's diverging because
|
||||
// of a `break` or an outer `break` or `return`.
|
||||
self.diverges.set(Diverges::Maybe);
|
||||
}
|
||||
|
||||
// If we permit break with a value, then result type is
|
||||
// the LUB of the breaks (possibly ! if none); else, it
|
||||
// is nil. This makes sense because infinite loops
|
||||
// (which would have type !) are only possible iff we
|
||||
// permit break with a value [1].
|
||||
if ctxt.coerce.is_none() && !ctxt.may_break {
|
||||
// [1]
|
||||
self.tcx.sess.delay_span_bug(body.span, "no coercion, but loop may not break");
|
||||
}
|
||||
ctxt.coerce.map(|c| c.complete(self)).unwrap_or_else(|| self.tcx.mk_unit())
|
||||
}
|
||||
ExprKind::Match(ref discrim, ref arms, match_src) => {
|
||||
self.check_match(expr, &discrim, arms, expected, match_src)
|
||||
}
|
||||
ExprKind::Closure(capture, ref decl, body_id, _, gen) => {
|
||||
self.check_expr_closure(expr, capture, &decl, body_id, gen, expected)
|
||||
}
|
||||
ExprKind::Block(ref body, _) => {
|
||||
self.check_block_with_expected(&body, expected)
|
||||
}
|
||||
ExprKind::Call(ref callee, ref args) => {
|
||||
self.check_call(expr, &callee, args, expected)
|
||||
}
|
||||
ExprKind::MethodCall(ref segment, span, ref args) => {
|
||||
self.check_method_call(expr, segment, span, args, expected, needs)
|
||||
}
|
||||
ExprKind::Cast(ref e, ref t) => {
|
||||
// Find the type of `e`. Supply hints based on the type we are casting to,
|
||||
// if appropriate.
|
||||
let t_cast = self.to_ty_saving_user_provided_ty(t);
|
||||
let t_cast = self.resolve_vars_if_possible(&t_cast);
|
||||
let t_expr = self.check_expr_with_expectation(e, ExpectCastableToType(t_cast));
|
||||
let t_cast = self.resolve_vars_if_possible(&t_cast);
|
||||
|
||||
// Eagerly check for some obvious errors.
|
||||
if t_expr.references_error() || t_cast.references_error() {
|
||||
tcx.types.err
|
||||
} else {
|
||||
// Defer other checks until we're done type checking.
|
||||
let mut deferred_cast_checks = self.deferred_cast_checks.borrow_mut();
|
||||
match cast::CastCheck::new(self, e, t_expr, t_cast, t.span, expr.span) {
|
||||
Ok(cast_check) => {
|
||||
deferred_cast_checks.push(cast_check);
|
||||
t_cast
|
||||
}
|
||||
Err(ErrorReported) => {
|
||||
tcx.types.err
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
ExprKind::Type(ref e, ref t) => {
|
||||
let ty = self.to_ty_saving_user_provided_ty(&t);
|
||||
self.check_expr_eq_type(&e, ty);
|
||||
ty
|
||||
}
|
||||
ExprKind::DropTemps(ref e) => {
|
||||
self.check_expr_with_expectation(e, expected)
|
||||
}
|
||||
ExprKind::Array(ref args) => {
|
||||
let uty = expected.to_option(self).and_then(|uty| {
|
||||
match uty.sty {
|
||||
ty::Array(ty, _) | ty::Slice(ty) => Some(ty),
|
||||
_ => None
|
||||
}
|
||||
});
|
||||
|
||||
let element_ty = if !args.is_empty() {
|
||||
let coerce_to = uty.unwrap_or_else(|| {
|
||||
self.next_ty_var(TypeVariableOrigin {
|
||||
kind: TypeVariableOriginKind::TypeInference,
|
||||
span: expr.span,
|
||||
})
|
||||
});
|
||||
let mut coerce = CoerceMany::with_coercion_sites(coerce_to, args);
|
||||
assert_eq!(self.diverges.get(), Diverges::Maybe);
|
||||
for e in args {
|
||||
let e_ty = self.check_expr_with_hint(e, coerce_to);
|
||||
let cause = self.misc(e.span);
|
||||
coerce.coerce(self, &cause, e, e_ty);
|
||||
}
|
||||
coerce.complete(self)
|
||||
} else {
|
||||
self.next_ty_var(TypeVariableOrigin {
|
||||
kind: TypeVariableOriginKind::TypeInference,
|
||||
span: expr.span,
|
||||
})
|
||||
};
|
||||
tcx.mk_array(element_ty, args.len() as u64)
|
||||
}
|
||||
ExprKind::Repeat(ref element, ref count) => {
|
||||
let count_def_id = tcx.hir().local_def_id_from_hir_id(count.hir_id);
|
||||
let count = if self.const_param_def_id(count).is_some() {
|
||||
Ok(self.to_const(count, self.tcx.type_of(count_def_id)))
|
||||
} else {
|
||||
let param_env = ty::ParamEnv::empty();
|
||||
let substs = InternalSubsts::identity_for_item(tcx.global_tcx(), count_def_id);
|
||||
let instance = ty::Instance::resolve(
|
||||
tcx.global_tcx(),
|
||||
param_env,
|
||||
count_def_id,
|
||||
substs,
|
||||
).unwrap();
|
||||
let global_id = GlobalId {
|
||||
instance,
|
||||
promoted: None
|
||||
};
|
||||
|
||||
tcx.const_eval(param_env.and(global_id))
|
||||
};
|
||||
|
||||
let uty = match expected {
|
||||
ExpectHasType(uty) => {
|
||||
match uty.sty {
|
||||
ty::Array(ty, _) | ty::Slice(ty) => Some(ty),
|
||||
_ => None
|
||||
}
|
||||
}
|
||||
_ => None
|
||||
};
|
||||
|
||||
let (element_ty, t) = match uty {
|
||||
Some(uty) => {
|
||||
self.check_expr_coercable_to_type(&element, uty);
|
||||
(uty, uty)
|
||||
}
|
||||
None => {
|
||||
let ty = self.next_ty_var(TypeVariableOrigin {
|
||||
kind: TypeVariableOriginKind::MiscVariable,
|
||||
span: element.span,
|
||||
});
|
||||
let element_ty = self.check_expr_has_type_or_error(&element, ty);
|
||||
(element_ty, ty)
|
||||
}
|
||||
};
|
||||
|
||||
if let Ok(count) = count {
|
||||
let zero_or_one = count.assert_usize(tcx).map_or(false, |count| count <= 1);
|
||||
if !zero_or_one {
|
||||
// For [foo, ..n] where n > 1, `foo` must have
|
||||
// Copy type:
|
||||
let lang_item = self.tcx.require_lang_item(lang_items::CopyTraitLangItem);
|
||||
self.require_type_meets(t, expr.span, traits::RepeatVec, lang_item);
|
||||
}
|
||||
}
|
||||
|
||||
if element_ty.references_error() {
|
||||
tcx.types.err
|
||||
} else if let Ok(count) = count {
|
||||
tcx.mk_ty(ty::Array(t, count))
|
||||
} else {
|
||||
tcx.types.err
|
||||
}
|
||||
}
|
||||
ExprKind::Tup(ref elts) => {
|
||||
let flds = expected.only_has_type(self).and_then(|ty| {
|
||||
let ty = self.resolve_type_vars_with_obligations(ty);
|
||||
match ty.sty {
|
||||
ty::Tuple(ref flds) => Some(&flds[..]),
|
||||
_ => None
|
||||
}
|
||||
});
|
||||
|
||||
let elt_ts_iter = elts.iter().enumerate().map(|(i, e)| {
|
||||
let t = match flds {
|
||||
Some(ref fs) if i < fs.len() => {
|
||||
let ety = fs[i].expect_ty();
|
||||
self.check_expr_coercable_to_type(&e, ety);
|
||||
ety
|
||||
}
|
||||
_ => {
|
||||
self.check_expr_with_expectation(&e, NoExpectation)
|
||||
}
|
||||
};
|
||||
t
|
||||
});
|
||||
let tuple = tcx.mk_tup(elt_ts_iter);
|
||||
if tuple.references_error() {
|
||||
tcx.types.err
|
||||
} else {
|
||||
self.require_type_is_sized(tuple, expr.span, traits::TupleInitializerSized);
|
||||
tuple
|
||||
}
|
||||
}
|
||||
ExprKind::Struct(ref qpath, ref fields, ref base_expr) => {
|
||||
self.check_expr_struct(expr, expected, qpath, fields, base_expr)
|
||||
}
|
||||
ExprKind::Field(ref base, field) => {
|
||||
self.check_field(expr, needs, &base, field)
|
||||
}
|
||||
ExprKind::Index(ref base, ref idx) => {
|
||||
let base_t = self.check_expr_with_needs(&base, needs);
|
||||
let idx_t = self.check_expr(&idx);
|
||||
|
||||
if base_t.references_error() {
|
||||
base_t
|
||||
} else if idx_t.references_error() {
|
||||
idx_t
|
||||
} else {
|
||||
let base_t = self.structurally_resolved_type(base.span, base_t);
|
||||
match self.lookup_indexing(expr, base, base_t, idx_t, needs) {
|
||||
Some((index_ty, element_ty)) => {
|
||||
// two-phase not needed because index_ty is never mutable
|
||||
self.demand_coerce(idx, idx_t, index_ty, AllowTwoPhase::No);
|
||||
element_ty
|
||||
}
|
||||
None => {
|
||||
let mut err =
|
||||
type_error_struct!(tcx.sess, expr.span, base_t, E0608,
|
||||
"cannot index into a value of type `{}`",
|
||||
base_t);
|
||||
// Try to give some advice about indexing tuples.
|
||||
if let ty::Tuple(..) = base_t.sty {
|
||||
let mut needs_note = true;
|
||||
// If the index is an integer, we can show the actual
|
||||
// fixed expression:
|
||||
if let ExprKind::Lit(ref lit) = idx.node {
|
||||
if let ast::LitKind::Int(i,
|
||||
ast::LitIntType::Unsuffixed) = lit.node {
|
||||
let snip = tcx.sess.source_map().span_to_snippet(base.span);
|
||||
if let Ok(snip) = snip {
|
||||
err.span_suggestion(
|
||||
expr.span,
|
||||
"to access tuple elements, use",
|
||||
format!("{}.{}", snip, i),
|
||||
Applicability::MachineApplicable,
|
||||
);
|
||||
needs_note = false;
|
||||
}
|
||||
}
|
||||
}
|
||||
if needs_note {
|
||||
err.help("to access tuple elements, use tuple indexing \
|
||||
syntax (e.g., `tuple.0`)");
|
||||
}
|
||||
}
|
||||
err.emit();
|
||||
self.tcx.types.err
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
ExprKind::Yield(ref value) => {
|
||||
match self.yield_ty {
|
||||
Some(ty) => {
|
||||
self.check_expr_coercable_to_type(&value, ty);
|
||||
}
|
||||
None => {
|
||||
struct_span_err!(self.tcx.sess, expr.span, E0627,
|
||||
"yield statement outside of generator literal").emit();
|
||||
}
|
||||
}
|
||||
tcx.mk_unit()
|
||||
}
|
||||
hir::ExprKind::Err => {
|
||||
tcx.types.err
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Type check assignment expression `expr` of form `lhs = rhs`.
|
||||
/// The expected type is `()` and is passsed to the function for the purposes of diagnostics.
|
||||
fn check_assign(
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue