| //! Type checking expressions. |
| //! |
| //! See `mod.rs` for more context on type checking in general. |
| |
| use crate::check::BreakableCtxt; |
| use crate::check::cast; |
| use crate::check::coercion::CoerceMany; |
| use crate::check::Diverges; |
| use crate::check::FnCtxt; |
| use crate::check::Expectation::{self, NoExpectation, ExpectHasType, ExpectCastableToType}; |
| use crate::check::fatally_break_rust; |
| use crate::check::report_unexpected_variant_res; |
| use crate::check::Needs; |
| use crate::check::TupleArgumentsFlag::DontTupleArguments; |
| use crate::check::method::{probe, SelfSource, MethodError}; |
| use crate::util::common::ErrorReported; |
| use crate::util::nodemap::FxHashMap; |
| use crate::astconv::AstConv as _; |
| |
| use errors::{Applicability, DiagnosticBuilder, pluralize}; |
| use syntax_pos::hygiene::DesugaringKind; |
| use syntax::ast; |
| use syntax::symbol::{Symbol, kw, sym}; |
| use syntax::source_map::Span; |
| use syntax::util::lev_distance::find_best_match_for_name; |
| use rustc::hir; |
| use rustc::hir::{ExprKind, QPath}; |
| use rustc::hir::def_id::DefId; |
| use rustc::hir::def::{CtorKind, Res, DefKind}; |
| use rustc::hir::ptr::P; |
| use rustc::infer; |
| use rustc::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; |
| use rustc::middle::lang_items; |
| use rustc::mir::interpret::GlobalId; |
| use rustc::ty; |
| use rustc::ty::adjustment::{ |
| Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability, |
| }; |
| use rustc::ty::{AdtKind, Visibility}; |
| use rustc::ty::Ty; |
| use rustc::ty::TypeFoldable; |
| use rustc::ty::subst::InternalSubsts; |
| use rustc::traits::{self, ObligationCauseCode}; |
| |
| use rustc_error_codes::*; |
| |
| use std::fmt::Display; |
| |
| impl<'a, 'tcx> FnCtxt<'a, 'tcx> { |
| fn check_expr_eq_type(&self, expr: &'tcx hir::Expr, expected: Ty<'tcx>) { |
| let ty = self.check_expr_with_hint(expr, expected); |
| self.demand_eqtype(expr.span, expected, ty); |
| } |
| |
| pub fn check_expr_has_type_or_error( |
| &self, |
| expr: &'tcx hir::Expr, |
| expected: Ty<'tcx>, |
| extend_err: impl Fn(&mut DiagnosticBuilder<'_>), |
| ) -> Ty<'tcx> { |
| self.check_expr_meets_expectation_or_error(expr, ExpectHasType(expected), extend_err) |
| } |
| |
| fn check_expr_meets_expectation_or_error( |
| &self, |
| expr: &'tcx hir::Expr, |
| expected: Expectation<'tcx>, |
| extend_err: impl Fn(&mut DiagnosticBuilder<'_>), |
| ) -> Ty<'tcx> { |
| let expected_ty = expected.to_option(&self).unwrap_or(self.tcx.types.bool); |
| let mut ty = self.check_expr_with_expectation(expr, expected); |
| |
| // While we don't allow *arbitrary* coercions here, we *do* allow |
| // coercions from ! to `expected`. |
| if ty.is_never() { |
| assert!(!self.tables.borrow().adjustments().contains_key(expr.hir_id), |
| "expression with never type wound up being adjusted"); |
| let adj_ty = self.next_diverging_ty_var( |
| TypeVariableOrigin { |
| kind: TypeVariableOriginKind::AdjustmentType, |
| span: expr.span, |
| }, |
| ); |
| self.apply_adjustments(expr, vec![Adjustment { |
| kind: Adjust::NeverToAny, |
| target: adj_ty |
| }]); |
| ty = adj_ty; |
| } |
| |
| if let Some(mut err) = self.demand_suptype_diag(expr.span, expected_ty, ty) { |
| let expr = expr.peel_drop_temps(); |
| self.suggest_ref_or_into(&mut err, expr, expected_ty, ty); |
| extend_err(&mut err); |
| // Error possibly reported in `check_assign` so avoid emitting error again. |
| err.emit_unless(self.is_assign_to_bool(expr, expected_ty)); |
| } |
| ty |
| } |
| |
| pub(super) fn check_expr_coercable_to_type( |
| &self, |
| expr: &'tcx hir::Expr, |
| expected: Ty<'tcx> |
| ) -> Ty<'tcx> { |
| let ty = self.check_expr_with_hint(expr, expected); |
| // checks don't need two phase |
| self.demand_coerce(expr, ty, expected, AllowTwoPhase::No) |
| } |
| |
| pub(super) fn check_expr_with_hint( |
| &self, |
| expr: &'tcx hir::Expr, |
| expected: Ty<'tcx> |
| ) -> Ty<'tcx> { |
| self.check_expr_with_expectation(expr, ExpectHasType(expected)) |
| } |
| |
| pub(super) fn check_expr_with_expectation( |
| &self, |
| expr: &'tcx hir::Expr, |
| expected: Expectation<'tcx>, |
| ) -> Ty<'tcx> { |
| self.check_expr_with_expectation_and_needs(expr, expected, Needs::None) |
| } |
| |
| pub(super) fn check_expr(&self, expr: &'tcx hir::Expr) -> Ty<'tcx> { |
| self.check_expr_with_expectation(expr, NoExpectation) |
| } |
| |
| pub(super) fn check_expr_with_needs(&self, expr: &'tcx hir::Expr, needs: Needs) -> Ty<'tcx> { |
| self.check_expr_with_expectation_and_needs(expr, NoExpectation, needs) |
| } |
| |
| /// 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 |
| /// true. Likewise, if an expression is known to diverge, inspecting its |
| /// type with `ty::type_is_bot` will return true (n.b.: since Rust is |
| /// strict, _|_ can appear in the type of an expression that does not, |
| /// itself, diverge: for example, fn() -> _|_.) |
| /// Note that inspecting a type's structure *directly* may expose the fact |
| /// that there are actually multiple representations for `Error`, so avoid |
| /// that when err needs to be handled differently. |
| fn check_expr_with_expectation_and_needs( |
| &self, |
| expr: &'tcx hir::Expr, |
| expected: Expectation<'tcx>, |
| needs: Needs, |
| ) -> Ty<'tcx> { |
| debug!(">> type-checking: expr={:?} expected={:?}", |
| expr, expected); |
| |
| // True if `expr` is a `Try::from_ok(())` that is a result of desugaring a try block |
| // without the final expr (e.g. `try { return; }`). We don't want to generate an |
| // unreachable_code lint for it since warnings for autogenerated code are confusing. |
| let is_try_block_generated_unit_expr = match expr.kind { |
| ExprKind::Call(_, ref args) if expr.span.is_desugaring(DesugaringKind::TryBlock) => |
| args.len() == 1 && args[0].span.is_desugaring(DesugaringKind::TryBlock), |
| |
| _ => false, |
| }; |
| |
| // Warn for expressions after diverging siblings. |
| if !is_try_block_generated_unit_expr { |
| self.warn_if_unreachable(expr.hir_id, expr.span, "expression"); |
| } |
| |
| // Hide the outer diverging and has_errors flags. |
| let old_diverges = self.diverges.get(); |
| let old_has_errors = self.has_errors.get(); |
| self.diverges.set(Diverges::Maybe); |
| self.has_errors.set(false); |
| |
| let ty = self.check_expr_kind(expr, expected, needs); |
| |
| // Warn for non-block expressions with diverging children. |
| match expr.kind { |
| ExprKind::Block(..) | ExprKind::Loop(..) | ExprKind::Match(..) => {}, |
| // If `expr` is a result of desugaring the try block and is an ok-wrapped |
| // diverging expression (e.g. it arose from desugaring of `try { return }`), |
| // we skip issuing a warning because it is autogenerated code. |
| ExprKind::Call(..) if expr.span.is_desugaring(DesugaringKind::TryBlock) => {}, |
| ExprKind::Call(ref callee, _) => |
| self.warn_if_unreachable(expr.hir_id, callee.span, "call"), |
| ExprKind::MethodCall(_, ref span, _) => |
| self.warn_if_unreachable(expr.hir_id, *span, "call"), |
| _ => self.warn_if_unreachable(expr.hir_id, expr.span, "expression"), |
| } |
| |
| // Any expression that produces a value of type `!` must have diverged |
| if ty.is_never() { |
| self.diverges.set(self.diverges.get() | Diverges::always(expr.span)); |
| } |
| |
| // Record the type, which applies it effects. |
| // We need to do this after the warning above, so that |
| // we don't warn for the diverging expression itself. |
| self.write_ty(expr.hir_id, ty); |
| |
| // Combine the diverging and has_error flags. |
| self.diverges.set(self.diverges.get() | old_diverges); |
| self.has_errors.set(self.has_errors.get() | old_has_errors); |
| |
| debug!("type of {} is...", self.tcx.hir().node_to_string(expr.hir_id)); |
| debug!("... {:?}, expected is {:?}", ty, expected); |
| |
| 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; |
| match expr.kind { |
| ExprKind::Box(ref subexpr) => { |
| self.check_expr_box(subexpr, expected) |
| } |
| 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) => { |
| self.check_expr_unary(unop, oprnd, expected, needs, expr) |
| } |
| ExprKind::AddrOf(kind, mutbl, ref oprnd) => { |
| self.check_expr_addr_of(kind, mutbl, oprnd, expected, expr) |
| } |
| ExprKind::Path(ref qpath) => { |
| self.check_expr_path(qpath, expr) |
| } |
| ExprKind::InlineAsm(ref asm) => { |
| for expr in asm.outputs_exprs.iter().chain(asm.inputs_exprs.iter()) { |
| self.check_expr(expr); |
| } |
| tcx.mk_unit() |
| } |
| ExprKind::Break(destination, ref expr_opt) => { |
| self.check_expr_break(destination, expr_opt.as_deref(), expr) |
| } |
| 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) => { |
| self.check_expr_return(expr_opt.as_deref(), expr) |
| } |
| ExprKind::Assign(ref lhs, ref rhs) => { |
| self.check_expr_assign(expr, expected, lhs, rhs) |
| } |
| ExprKind::Loop(ref body, _, source) => { |
| self.check_expr_loop(body, source, expected, expr) |
| } |
| 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) => { |
| self.check_expr_cast(e, t, expr) |
| } |
| 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) => { |
| self.check_expr_array(args, expected, expr) |
| } |
| ExprKind::Repeat(ref element, ref count) => { |
| self.check_expr_repeat(element, count, expected, expr) |
| } |
| ExprKind::Tup(ref elts) => { |
| self.check_expr_tuple(elts, expected, expr) |
| } |
| 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) => { |
| self.check_expr_index(base, idx, needs, expr) |
| } |
| ExprKind::Yield(ref value, ref src) => { |
| self.check_expr_yield(value, expr, src) |
| } |
| hir::ExprKind::Err => { |
| tcx.types.err |
| } |
| } |
| } |
| |
| fn check_expr_box(&self, expr: &'tcx hir::Expr, expected: Expectation<'tcx>) -> Ty<'tcx> { |
| let expected_inner = expected.to_option(self).map_or(NoExpectation, |ty| { |
| match ty.kind { |
| ty::Adt(def, _) if def.is_box() |
| => Expectation::rvalue_hint(self, ty.boxed_ty()), |
| _ => NoExpectation |
| } |
| }); |
| let referent_ty = self.check_expr_with_expectation(expr, expected_inner); |
| self.tcx.mk_box(referent_ty) |
| } |
| |
| fn check_expr_unary( |
| &self, |
| unop: hir::UnOp, |
| oprnd: &'tcx hir::Expr, |
| expected: Expectation<'tcx>, |
| needs: Needs, |
| expr: &'tcx hir::Expr, |
| ) -> Ty<'tcx> { |
| let tcx = self.tcx; |
| 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].kind { |
| let mutbl = match mutbl { |
| hir::Mutability::Immutable => AutoBorrowMutability::Immutable, |
| hir::Mutability::Mutable => 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.kind == 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 |
| } |
| |
| fn check_expr_addr_of( |
| &self, |
| kind: hir::BorrowKind, |
| mutbl: hir::Mutability, |
| oprnd: &'tcx hir::Expr, |
| expected: Expectation<'tcx>, |
| expr: &'tcx hir::Expr, |
| ) -> Ty<'tcx> { |
| let hint = expected.only_has_type(self).map_or(NoExpectation, |ty| { |
| match ty.kind { |
| ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => { |
| if oprnd.is_syntactic_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 }; |
| match kind { |
| _ if tm.ty.references_error() => self.tcx.types.err, |
| hir::BorrowKind::Raw => { |
| self.check_named_place_expr(oprnd); |
| self.tcx.mk_ptr(tm) |
| } |
| hir::BorrowKind::Ref => { |
| // 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 a suitable value. |
| // Finally, borrowck will infer the value of the region again, |
| // this time with enough precision to check 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)); |
| self.tcx.mk_ref(region, tm) |
| } |
| } |
| } |
| |
| /// Does this expression refer to a place that either: |
| /// * Is based on a local or static. |
| /// * Contains a dereference |
| /// Note that the adjustments for the children of `expr` should already |
| /// have been resolved. |
| fn check_named_place_expr(&self, oprnd: &'tcx hir::Expr) { |
| let is_named = oprnd.is_place_expr(|base| { |
| // Allow raw borrows if there are any deref adjustments. |
| // |
| // const VAL: (i32,) = (0,); |
| // const REF: &(i32,) = &(0,); |
| // |
| // &raw const VAL.0; // ERROR |
| // &raw const REF.0; // OK, same as &raw const (*REF).0; |
| // |
| // This is maybe too permissive, since it allows |
| // `let u = &raw const Box::new((1,)).0`, which creates an |
| // immediately dangling raw pointer. |
| self.tables.borrow().adjustments().get(base.hir_id).map_or(false, |x| { |
| x.iter().any(|adj| if let Adjust::Deref(_) = adj.kind { |
| true |
| } else { |
| false |
| }) |
| }) |
| }); |
| if !is_named { |
| struct_span_err!(self.tcx.sess, oprnd.span, E0745, "cannot take address of a temporary") |
| .span_label(oprnd.span, "temporary value") |
| .emit(); |
| } |
| } |
| |
| fn check_expr_path(&self, qpath: &hir::QPath, expr: &'tcx hir::Expr) -> Ty<'tcx> { |
| let tcx = self.tcx; |
| 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, expr.hir_id).0, |
| }; |
| |
| if let ty::FnDef(..) = ty.kind { |
| 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 presence 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 |
| } |
| |
| fn check_expr_break( |
| &self, |
| destination: hir::Destination, |
| expr_opt: Option<&'tcx hir::Expr>, |
| expr: &'tcx hir::Expr, |
| ) -> Ty<'tcx> { |
| let tcx = self.tcx; |
| 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 = { |
| // We should release `enclosing_breakables` before the `check_expr_with_hint` |
| // below, so can't move this block of code to the enclosing scope and share |
| // `ctxt` with the second `encloding_breakables` borrow below. |
| let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); |
| match enclosing_breakables.opt_find_breakable(target_id) { |
| Some(ctxt) => |
| ctxt.coerce.as_ref().map(|coerce| coerce.expected_ty()), |
| None => { // Avoid ICE when `break` is inside a closure (#65383). |
| self.tcx.sess.delay_span_bug( |
| expr.span, |
| "break was outside loop, but no error was emitted", |
| ); |
| return tcx.types.err; |
| } |
| } |
| }; |
| |
| // 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 = match enclosing_breakables.opt_find_breakable(target_id) { |
| Some(ctxt) => ctxt, |
| None => { // Avoid ICE when `break` is inside a closure (#65383). |
| self.tcx.sess.delay_span_bug( |
| expr.span, |
| "break was outside loop, but no error was emitted", |
| ); |
| return tcx.types.err; |
| } |
| }; |
| |
| 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()); |
| let ty = coerce.expected_ty(); |
| coerce.coerce_forced_unit(self, &cause, &mut |mut err| { |
| self.suggest_mismatched_types_on_tail( |
| &mut err, |
| expr, |
| ty, |
| e_ty, |
| cause.span, |
| target_id, |
| ); |
| if let Some(val) = ty_kind_suggestion(ty) { |
| let label = destination.label |
| .map(|l| format!(" {}", l.ident)) |
| .unwrap_or_else(String::new); |
| err.span_suggestion( |
| expr.span, |
| "give it a value of the expected type", |
| format!("break{} {}", label, val), |
| Applicability::HasPlaceholders, |
| ); |
| } |
| }, false); |
| } |
| } else { |
| // If `ctxt.coerce` is `None`, we can just ignore |
| // the type of the expression. 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.has_errors()); |
| } |
| |
| 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. |
| 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.kind { |
| 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 |
| } |
| } |
| |
| fn check_expr_return( |
| &self, |
| expr_opt: Option<&'tcx hir::Expr>, |
| expr: &'tcx hir::Expr |
| ) -> Ty<'tcx> { |
| 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); |
| } |
| } |
| self.tcx.types.never |
| } |
| |
| pub(super) fn check_return_expr(&self, return_expr: &'tcx hir::Expr) { |
| let ret_coercion = |
| self.ret_coercion |
| .as_ref() |
| .unwrap_or_else(|| span_bug!(return_expr.span, |
| "check_return_expr called outside fn body")); |
| |
| let ret_ty = ret_coercion.borrow().expected_ty(); |
| let return_expr_ty = self.check_expr_with_hint(return_expr, ret_ty.clone()); |
| ret_coercion.borrow_mut().coerce( |
| self, |
| &self.cause(return_expr.span, ObligationCauseCode::ReturnValue(return_expr.hir_id)), |
| return_expr, |
| return_expr_ty, |
| ); |
| } |
| |
| /// 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_expr_assign( |
| &self, |
| expr: &'tcx hir::Expr, |
| expected: Expectation<'tcx>, |
| lhs: &'tcx hir::Expr, |
| rhs: &'tcx hir::Expr, |
| ) -> Ty<'tcx> { |
| let lhs_ty = self.check_expr_with_needs(&lhs, Needs::MutPlace); |
| let rhs_ty = self.check_expr_coercable_to_type(&rhs, lhs_ty); |
| |
| let expected_ty = expected.coercion_target_type(self, expr.span); |
| if expected_ty == self.tcx.types.bool { |
| // The expected type is `bool` but this will result in `()` so we can reasonably |
| // say that the user intended to write `lhs == rhs` instead of `lhs = rhs`. |
| // The likely cause of this is `if foo = bar { .. }`. |
| let actual_ty = self.tcx.mk_unit(); |
| let mut err = self.demand_suptype_diag(expr.span, expected_ty, actual_ty).unwrap(); |
| let msg = "try comparing for equality"; |
| let left = self.tcx.sess.source_map().span_to_snippet(lhs.span); |
| let right = self.tcx.sess.source_map().span_to_snippet(rhs.span); |
| if let (Ok(left), Ok(right)) = (left, right) { |
| let help = format!("{} == {}", left, right); |
| err.span_suggestion(expr.span, msg, help, Applicability::MaybeIncorrect); |
| } else { |
| err.help(msg); |
| } |
| err.emit(); |
| } else if !lhs.is_syntactic_place_expr() { |
| struct_span_err!(self.tcx.sess, expr.span, E0070, |
| "invalid left-hand side expression") |
| .span_label(expr.span, "left-hand of expression not valid") |
| .emit(); |
| } |
| |
| self.require_type_is_sized(lhs_ty, lhs.span, traits::AssignmentLhsSized); |
| |
| if lhs_ty.references_error() || rhs_ty.references_error() { |
| self.tcx.types.err |
| } else { |
| self.tcx.mk_unit() |
| } |
| } |
| |
| fn check_expr_loop( |
| &self, |
| body: &'tcx hir::Block, |
| source: hir::LoopSource, |
| expected: Expectation<'tcx>, |
| expr: &'tcx hir::Expr, |
| ) -> Ty<'tcx> { |
| 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::While | |
| 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()) |
| } |
| |
| /// Checks a method call. |
| fn check_method_call( |
| &self, |
| expr: &'tcx hir::Expr, |
| segment: &hir::PathSegment, |
| span: Span, |
| args: &'tcx [hir::Expr], |
| expected: Expectation<'tcx>, |
| needs: Needs, |
| ) -> Ty<'tcx> { |
| let rcvr = &args[0]; |
| let rcvr_t = self.check_expr_with_needs(&rcvr, needs); |
| // no need to check for bot/err -- callee does that |
| let rcvr_t = self.structurally_resolved_type(args[0].span, rcvr_t); |
| |
| let method = match self.lookup_method(rcvr_t, segment, span, expr, rcvr) { |
| Ok(method) => { |
| self.write_method_call(expr.hir_id, method); |
| Ok(method) |
| } |
| Err(error) => { |
| if segment.ident.name != kw::Invalid { |
| self.report_extended_method_error(segment, span, args, rcvr_t, error); |
| } |
| Err(()) |
| } |
| }; |
| |
| // Call the generic checker. |
| self.check_method_argument_types( |
| span, |
| expr, |
| method, |
| &args[1..], |
| DontTupleArguments, |
| expected, |
| ) |
| } |
| |
| fn report_extended_method_error( |
| &self, |
| segment: &hir::PathSegment, |
| span: Span, |
| args: &'tcx [hir::Expr], |
| rcvr_t: Ty<'tcx>, |
| error: MethodError<'tcx> |
| ) { |
| let rcvr = &args[0]; |
| let try_alt_rcvr = |err: &mut DiagnosticBuilder<'_>, rcvr_t, lang_item| { |
| if let Some(new_rcvr_t) = self.tcx.mk_lang_item(rcvr_t, lang_item) { |
| if let Ok(pick) = self.lookup_probe( |
| span, |
| segment.ident, |
| new_rcvr_t, |
| rcvr, |
| probe::ProbeScope::AllTraits, |
| ) { |
| err.span_label( |
| pick.item.ident.span, |
| &format!("the method is available for `{}` here", new_rcvr_t), |
| ); |
| } |
| } |
| }; |
| |
| if let Some(mut err) = self.report_method_error( |
| span, |
| rcvr_t, |
| segment.ident, |
| SelfSource::MethodCall(rcvr), |
| error, |
| Some(args), |
| ) { |
| if let ty::Adt(..) = rcvr_t.kind { |
| // Try alternative arbitrary self types that could fulfill this call. |
| // FIXME: probe for all types that *could* be arbitrary self-types, not |
| // just this whitelist. |
| try_alt_rcvr(&mut err, rcvr_t, lang_items::OwnedBoxLangItem); |
| try_alt_rcvr(&mut err, rcvr_t, lang_items::PinTypeLangItem); |
| try_alt_rcvr(&mut err, rcvr_t, lang_items::Arc); |
| try_alt_rcvr(&mut err, rcvr_t, lang_items::Rc); |
| } |
| err.emit(); |
| } |
| } |
| |
| fn check_expr_cast( |
| &self, |
| e: &'tcx hir::Expr, |
| t: &'tcx hir::Ty, |
| expr: &'tcx hir::Expr, |
| ) -> Ty<'tcx> { |
| // 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() { |
| self.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) => { |
| self.tcx.types.err |
| } |
| } |
| } |
| } |
| |
| fn check_expr_array( |
| &self, |
| args: &'tcx [hir::Expr], |
| expected: Expectation<'tcx>, |
| expr: &'tcx hir::Expr |
| ) -> Ty<'tcx> { |
| let uty = expected.to_option(self).and_then(|uty| { |
| match uty.kind { |
| 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, |
| }) |
| }; |
| self.tcx.mk_array(element_ty, args.len() as u64) |
| } |
| |
| fn check_expr_repeat( |
| &self, |
| element: &'tcx hir::Expr, |
| count: &'tcx hir::AnonConst, |
| expected: Expectation<'tcx>, |
| _expr: &'tcx hir::Expr, |
| ) -> Ty<'tcx> { |
| let tcx = self.tcx; |
| let count_def_id = tcx.hir().local_def_id(count.hir_id); |
| let count = if self.const_param_def_id(count).is_some() { |
| Ok(self.to_const(count, tcx.type_of(count_def_id))) |
| } else { |
| let param_env = ty::ParamEnv::empty(); |
| let substs = InternalSubsts::identity_for_item(tcx, count_def_id); |
| let instance = ty::Instance::resolve( |
| 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.kind { |
| 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 element_ty.references_error() { |
| tcx.types.err |
| } else if let Ok(count) = count { |
| tcx.mk_ty(ty::Array(t, count)) |
| } else { |
| tcx.types.err |
| } |
| } |
| |
| fn check_expr_tuple( |
| &self, |
| elts: &'tcx [hir::Expr], |
| expected: Expectation<'tcx>, |
| expr: &'tcx hir::Expr, |
| ) -> Ty<'tcx> { |
| let flds = expected.only_has_type(self).and_then(|ty| { |
| let ty = self.resolve_vars_with_obligations(ty); |
| match ty.kind { |
| 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 = self.tcx.mk_tup(elt_ts_iter); |
| if tuple.references_error() { |
| self.tcx.types.err |
| } else { |
| self.require_type_is_sized(tuple, expr.span, traits::TupleInitializerSized); |
| tuple |
| } |
| } |
| |
| fn check_expr_struct( |
| &self, |
| expr: &hir::Expr, |
| expected: Expectation<'tcx>, |
| qpath: &QPath, |
| fields: &'tcx [hir::Field], |
| base_expr: &'tcx Option<P<hir::Expr>>, |
| ) -> Ty<'tcx> { |
| // Find the relevant variant |
| let (variant, adt_ty) = |
| if let Some(variant_ty) = self.check_struct_path(qpath, expr.hir_id) { |
| variant_ty |
| } else { |
| self.check_struct_fields_on_error(fields, base_expr); |
| return self.tcx.types.err; |
| }; |
| |
| let path_span = match *qpath { |
| QPath::Resolved(_, ref path) => path.span, |
| QPath::TypeRelative(ref qself, _) => qself.span |
| }; |
| |
| // Prohibit struct expressions when non-exhaustive flag is set. |
| let adt = adt_ty.ty_adt_def().expect("`check_struct_path` returned non-ADT type"); |
| if !adt.did.is_local() && variant.is_field_list_non_exhaustive() { |
| span_err!(self.tcx.sess, expr.span, E0639, |
| "cannot create non-exhaustive {} using struct expression", |
| adt.variant_descr()); |
| } |
| |
| let error_happened = self.check_expr_struct_fields(adt_ty, expected, expr.hir_id, path_span, |
| variant, fields, base_expr.is_none()); |
| if let &Some(ref base_expr) = base_expr { |
| // If check_expr_struct_fields hit an error, do not attempt to populate |
| // the fields with the base_expr. This could cause us to hit errors later |
| // when certain fields are assumed to exist that in fact do not. |
| if !error_happened { |
| self.check_expr_has_type_or_error(base_expr, adt_ty, |_| {}); |
| match adt_ty.kind { |
| ty::Adt(adt, substs) if adt.is_struct() => { |
| let fru_field_types = adt.non_enum_variant().fields.iter().map(|f| { |
| self.normalize_associated_types_in(expr.span, &f.ty(self.tcx, substs)) |
| }).collect(); |
| |
| self.tables |
| .borrow_mut() |
| .fru_field_types_mut() |
| .insert(expr.hir_id, fru_field_types); |
| } |
| _ => { |
| span_err!(self.tcx.sess, base_expr.span, E0436, |
| "functional record update syntax requires a struct"); |
| } |
| } |
| } |
| } |
| self.require_type_is_sized(adt_ty, expr.span, traits::StructInitializerSized); |
| adt_ty |
| } |
| |
| fn check_expr_struct_fields( |
| &self, |
| adt_ty: Ty<'tcx>, |
| expected: Expectation<'tcx>, |
| expr_id: hir::HirId, |
| span: Span, |
| variant: &'tcx ty::VariantDef, |
| ast_fields: &'tcx [hir::Field], |
| check_completeness: bool, |
| ) -> bool { |
| let tcx = self.tcx; |
| |
| let adt_ty_hint = |
| self.expected_inputs_for_expected_output(span, expected, adt_ty, &[adt_ty]) |
| .get(0).cloned().unwrap_or(adt_ty); |
| // re-link the regions that EIfEO can erase. |
| self.demand_eqtype(span, adt_ty_hint, adt_ty); |
| |
| let (substs, adt_kind, kind_name) = match &adt_ty.kind { |
| &ty::Adt(adt, substs) => { |
| (substs, adt.adt_kind(), adt.variant_descr()) |
| } |
| _ => span_bug!(span, "non-ADT passed to check_expr_struct_fields") |
| }; |
| |
| let mut remaining_fields = variant.fields.iter().enumerate().map(|(i, field)| |
| (field.ident.modern(), (i, field)) |
| ).collect::<FxHashMap<_, _>>(); |
| |
| let mut seen_fields = FxHashMap::default(); |
| |
| let mut error_happened = false; |
| |
| // Type-check each field. |
| for field in ast_fields { |
| let ident = tcx.adjust_ident(field.ident, variant.def_id); |
| let field_type = if let Some((i, v_field)) = remaining_fields.remove(&ident) { |
| seen_fields.insert(ident, field.span); |
| self.write_field_index(field.hir_id, i); |
| |
| // We don't look at stability attributes on |
| // struct-like enums (yet...), but it's definitely not |
| // a bug to have constructed one. |
| if adt_kind != AdtKind::Enum { |
| tcx.check_stability(v_field.did, Some(expr_id), field.span); |
| } |
| |
| self.field_ty(field.span, v_field, substs) |
| } else { |
| error_happened = true; |
| if let Some(prev_span) = seen_fields.get(&ident) { |
| let mut err = struct_span_err!(self.tcx.sess, |
| field.ident.span, |
| E0062, |
| "field `{}` specified more than once", |
| ident); |
| |
| err.span_label(field.ident.span, "used more than once"); |
| err.span_label(*prev_span, format!("first use of `{}`", ident)); |
| |
| err.emit(); |
| } else { |
| self.report_unknown_field(adt_ty, variant, field, ast_fields, kind_name, span); |
| } |
| |
| tcx.types.err |
| }; |
| |
| // Make sure to give a type to the field even if there's |
| // an error, so we can continue type-checking. |
| self.check_expr_coercable_to_type(&field.expr, field_type); |
| } |
| |
| // Make sure the programmer specified correct number of fields. |
| if kind_name == "union" { |
| if ast_fields.len() != 1 { |
| tcx.sess.span_err(span, "union expressions should have exactly one field"); |
| } |
| } else if check_completeness && !error_happened && !remaining_fields.is_empty() { |
| let len = remaining_fields.len(); |
| |
| let mut displayable_field_names = remaining_fields |
| .keys() |
| .map(|ident| ident.as_str()) |
| .collect::<Vec<_>>(); |
| |
| displayable_field_names.sort(); |
| |
| let truncated_fields_error = if len <= 3 { |
| String::new() |
| } else { |
| format!(" and {} other field{}", (len - 3), if len - 3 == 1 {""} else {"s"}) |
| }; |
| |
| let remaining_fields_names = displayable_field_names.iter().take(3) |
| .map(|n| format!("`{}`", n)) |
| .collect::<Vec<_>>() |
| .join(", "); |
| |
| struct_span_err!(tcx.sess, span, E0063, |
| "missing field{} {}{} in initializer of `{}`", |
| pluralize!(remaining_fields.len()), |
| remaining_fields_names, |
| truncated_fields_error, |
| adt_ty) |
| .span_label(span, format!("missing {}{}", |
| remaining_fields_names, |
| truncated_fields_error)) |
| .emit(); |
| } |
| error_happened |
| } |
| |
| fn check_struct_fields_on_error( |
| &self, |
| fields: &'tcx [hir::Field], |
| base_expr: &'tcx Option<P<hir::Expr>>, |
| ) { |
| for field in fields { |
| self.check_expr(&field.expr); |
| } |
| if let Some(ref base) = *base_expr { |
| self.check_expr(&base); |
| } |
| } |
| |
| fn report_unknown_field( |
| &self, |
| ty: Ty<'tcx>, |
| variant: &'tcx ty::VariantDef, |
| field: &hir::Field, |
| skip_fields: &[hir::Field], |
| kind_name: &str, |
| ty_span: Span |
| ) { |
| if variant.recovered { |
| return; |
| } |
| let mut err = self.type_error_struct_with_diag( |
| field.ident.span, |
| |actual| match ty.kind { |
| ty::Adt(adt, ..) if adt.is_enum() => { |
| struct_span_err!(self.tcx.sess, field.ident.span, E0559, |
| "{} `{}::{}` has no field named `{}`", |
| kind_name, actual, variant.ident, field.ident) |
| } |
| _ => { |
| struct_span_err!(self.tcx.sess, field.ident.span, E0560, |
| "{} `{}` has no field named `{}`", |
| kind_name, actual, field.ident) |
| } |
| }, |
| ty); |
| match variant.ctor_kind { |
| CtorKind::Fn => { |
| err.span_label(variant.ident.span, format!("`{adt}` defined here", adt=ty)); |
| err.span_label(field.ident.span, "field does not exist"); |
| err.span_label(ty_span, format!( |
| "`{adt}` is a tuple {kind_name}, \ |
| use the appropriate syntax: `{adt}(/* fields */)`", |
| adt=ty, |
| kind_name=kind_name |
| )); |
| } |
| _ => { |
| // prevent all specified fields from being suggested |
| let skip_fields = skip_fields.iter().map(|ref x| x.ident.name); |
| if let Some(field_name) = Self::suggest_field_name( |
| variant, |
| &field.ident.as_str(), |
| skip_fields.collect() |
| ) { |
| err.span_suggestion( |
| field.ident.span, |
| "a field with a similar name exists", |
| field_name.to_string(), |
| Applicability::MaybeIncorrect, |
| ); |
| } else { |
| match ty.kind { |
| ty::Adt(adt, ..) => { |
| if adt.is_enum() { |
| err.span_label(field.ident.span, format!( |
| "`{}::{}` does not have this field", |
| ty, |
| variant.ident |
| )); |
| } else { |
| err.span_label(field.ident.span, format!( |
| "`{}` does not have this field", |
| ty |
| )); |
| } |
| let available_field_names = self.available_field_names(variant); |
| if !available_field_names.is_empty() { |
| err.note(&format!("available fields are: {}", |
| self.name_series_display(available_field_names))); |
| } |
| } |
| _ => bug!("non-ADT passed to report_unknown_field") |
| } |
| }; |
| } |
| } |
| err.emit(); |
| } |
| |
| // Return an hint about the closest match in field names |
| fn suggest_field_name(variant: &'tcx ty::VariantDef, |
| field: &str, |
| skip: Vec<Symbol>) |
| -> Option<Symbol> { |
| let names = variant.fields.iter().filter_map(|field| { |
| // ignore already set fields and private fields from non-local crates |
| if skip.iter().any(|&x| x == field.ident.name) || |
| (!variant.def_id.is_local() && field.vis != Visibility::Public) |
| { |
| None |
| } else { |
| Some(&field.ident.name) |
| } |
| }); |
| |
| find_best_match_for_name(names, field, None) |
| } |
| |
| fn available_field_names(&self, variant: &'tcx ty::VariantDef) -> Vec<ast::Name> { |
| variant.fields.iter().filter(|field| { |
| let def_scope = |
| self.tcx.adjust_ident_and_get_scope(field.ident, variant.def_id, self.body_id).1; |
| field.vis.is_accessible_from(def_scope, self.tcx) |
| }) |
| .map(|field| field.ident.name) |
| .collect() |
| } |
| |
| fn name_series_display(&self, names: Vec<ast::Name>) -> String { |
| // dynamic limit, to never omit just one field |
| let limit = if names.len() == 6 { 6 } else { 5 }; |
| let mut display = names.iter().take(limit) |
| .map(|n| format!("`{}`", n)).collect::<Vec<_>>().join(", "); |
| if names.len() > limit { |
| display = format!("{} ... and {} others", display, names.len() - limit); |
| } |
| display |
| } |
| |
| // Check field access expressions |
| fn check_field( |
| &self, |
| expr: &'tcx hir::Expr, |
| needs: Needs, |
| base: &'tcx hir::Expr, |
| field: ast::Ident, |
| ) -> Ty<'tcx> { |
| let expr_t = self.check_expr_with_needs(base, needs); |
| let expr_t = self.structurally_resolved_type(base.span, |
| expr_t); |
| let mut private_candidate = None; |
| let mut autoderef = self.autoderef(expr.span, expr_t); |
| while let Some((base_t, _)) = autoderef.next() { |
| match base_t.kind { |
| ty::Adt(base_def, substs) if !base_def.is_enum() => { |
| debug!("struct named {:?}", base_t); |
| let (ident, def_scope) = |
| self.tcx.adjust_ident_and_get_scope(field, base_def.did, self.body_id); |
| let fields = &base_def.non_enum_variant().fields; |
| if let Some(index) = fields.iter().position(|f| f.ident.modern() == ident) { |
| let field = &fields[index]; |
| let field_ty = self.field_ty(expr.span, field, substs); |
| // Save the index of all fields regardless of their visibility in case |
| // of error recovery. |
| self.write_field_index(expr.hir_id, index); |
| if field.vis.is_accessible_from(def_scope, self.tcx) { |
| let adjustments = autoderef.adjust_steps(self, needs); |
| self.apply_adjustments(base, adjustments); |
| autoderef.finalize(self); |
| |
| self.tcx.check_stability(field.did, Some(expr.hir_id), expr.span); |
| return field_ty; |
| } |
| private_candidate = Some((base_def.did, field_ty)); |
| } |
| } |
| ty::Tuple(ref tys) => { |
| let fstr = field.as_str(); |
| if let Ok(index) = fstr.parse::<usize>() { |
| if fstr == index.to_string() { |
| if let Some(field_ty) = tys.get(index) { |
| let adjustments = autoderef.adjust_steps(self, needs); |
| self.apply_adjustments(base, adjustments); |
| autoderef.finalize(self); |
| |
| self.write_field_index(expr.hir_id, index); |
| return field_ty.expect_ty(); |
| } |
| } |
| } |
| } |
| _ => {} |
| } |
| } |
| autoderef.unambiguous_final_ty(self); |
| |
| if let Some((did, field_ty)) = private_candidate { |
| self.ban_private_field_access(expr, expr_t, field, did); |
| return field_ty; |
| } |
| |
| if field.name == kw::Invalid { |
| } else if self.method_exists(field, expr_t, expr.hir_id, true) { |
| self.ban_take_value_of_method(expr, expr_t, field); |
| } else if !expr_t.is_primitive_ty() { |
| self.ban_nonexisting_field(field, base, expr, expr_t); |
| } else { |
| type_error_struct!( |
| self.tcx().sess, |
| field.span, |
| expr_t, |
| E0610, |
| "`{}` is a primitive type and therefore doesn't have fields", |
| expr_t |
| ) |
| .emit(); |
| } |
| |
| self.tcx().types.err |
| } |
| |
| fn ban_nonexisting_field( |
| &self, |
| field: ast::Ident, |
| base: &'tcx hir::Expr, |
| expr: &'tcx hir::Expr, |
| expr_t: Ty<'tcx>, |
| ) { |
| let mut err = self.no_such_field_err(field.span, field, expr_t); |
| |
| match expr_t.peel_refs().kind { |
| ty::Array(_, len) => { |
| self.maybe_suggest_array_indexing(&mut err, expr, base, field, len); |
| } |
| ty::RawPtr(..) => { |
| self.suggest_first_deref_field(&mut err, expr, base, field); |
| } |
| ty::Adt(def, _) if !def.is_enum() => { |
| self.suggest_fields_on_recordish(&mut err, def, field); |
| } |
| ty::Param(param_ty) => { |
| self.point_at_param_definition(&mut err, param_ty); |
| } |
| _ => {} |
| } |
| |
| if field.name == kw::Await { |
| // We know by construction that `<expr>.await` is either on Rust 2015 |
| // or results in `ExprKind::Await`. Suggest switching the edition to 2018. |
| err.note("to `.await` a `Future`, switch to Rust 2018"); |
| err.help("set `edition = \"2018\"` in `Cargo.toml`"); |
| err.note("for more on editions, read https://doc.rust-lang.org/edition-guide"); |
| } |
| |
| err.emit(); |
| } |
| |
| fn ban_private_field_access( |
| &self, |
| expr: &hir::Expr, |
| expr_t: Ty<'tcx>, |
| field: ast::Ident, |
| base_did: DefId, |
| ) { |
| let struct_path = self.tcx().def_path_str(base_did); |
| let kind_name = match self.tcx().def_kind(base_did) { |
| Some(def_kind) => def_kind.descr(base_did), |
| _ => " ", |
| }; |
| let mut err = struct_span_err!( |
| self.tcx().sess, |
| expr.span, |
| E0616, |
| "field `{}` of {} `{}` is private", |
| field, |
| kind_name, |
| struct_path |
| ); |
| // Also check if an accessible method exists, which is often what is meant. |
| if self.method_exists(field, expr_t, expr.hir_id, false) |
| && !self.expr_in_place(expr.hir_id) |
| { |
| self.suggest_method_call( |
| &mut err, |
| &format!("a method `{}` also exists, call it with parentheses", field), |
| field, |
| expr_t, |
| expr.hir_id, |
| ); |
| } |
| err.emit(); |
| } |
| |
| fn ban_take_value_of_method(&self, expr: &hir::Expr, expr_t: Ty<'tcx>, field: ast::Ident) { |
| let mut err = type_error_struct!( |
| self.tcx().sess, |
| field.span, |
| expr_t, |
| E0615, |
| "attempted to take value of method `{}` on type `{}`", |
| field, |
| expr_t |
| ); |
| |
| if !self.expr_in_place(expr.hir_id) { |
| self.suggest_method_call( |
| &mut err, |
| "use parentheses to call the method", |
| field, |
| expr_t, |
| expr.hir_id |
| ); |
| } else { |
| err.help("methods are immutable and cannot be assigned to"); |
| } |
| |
| err.emit(); |
| } |
| |
| fn point_at_param_definition(&self, err: &mut DiagnosticBuilder<'_>, param: ty::ParamTy) { |
| let generics = self.tcx.generics_of(self.body_id.owner_def_id()); |
| let generic_param = generics.type_param(¶m, self.tcx); |
| if let ty::GenericParamDefKind::Type{synthetic: Some(..), ..} = generic_param.kind { |
| return; |
| } |
| let param_def_id = generic_param.def_id; |
| let param_hir_id = match self.tcx.hir().as_local_hir_id(param_def_id) { |
| Some(x) => x, |
| None => return, |
| }; |
| let param_span = self.tcx.hir().span(param_hir_id); |
| let param_name = self.tcx.hir().ty_param_name(param_hir_id); |
| |
| err.span_label(param_span, &format!("type parameter '{}' declared here", param_name)); |
| } |
| |
| fn suggest_fields_on_recordish( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| def: &'tcx ty::AdtDef, |
| field: ast::Ident, |
| ) { |
| if let Some(suggested_field_name) = |
| Self::suggest_field_name(def.non_enum_variant(), &field.as_str(), vec![]) |
| { |
| err.span_suggestion( |
| field.span, |
| "a field with a similar name exists", |
| suggested_field_name.to_string(), |
| Applicability::MaybeIncorrect, |
| ); |
| } else { |
| err.span_label(field.span, "unknown field"); |
| let struct_variant_def = def.non_enum_variant(); |
| let field_names = self.available_field_names(struct_variant_def); |
| if !field_names.is_empty() { |
| err.note(&format!( |
| "available fields are: {}", |
| self.name_series_display(field_names), |
| )); |
| } |
| } |
| } |
| |
| fn maybe_suggest_array_indexing( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| expr: &hir::Expr, |
| base: &hir::Expr, |
| field: ast::Ident, |
| len: &ty::Const<'tcx>, |
| ) { |
| if let (Some(len), Ok(user_index)) = ( |
| len.try_eval_usize(self.tcx, self.param_env), |
| field.as_str().parse::<u64>() |
| ) { |
| let base = self.tcx.sess.source_map() |
| .span_to_snippet(base.span) |
| .unwrap_or_else(|_| self.tcx.hir().hir_to_pretty_string(base.hir_id)); |
| let help = "instead of using tuple indexing, use array indexing"; |
| let suggestion = format!("{}[{}]", base, field); |
| let applicability = if len < user_index { |
| Applicability::MachineApplicable |
| } else { |
| Applicability::MaybeIncorrect |
| }; |
| err.span_suggestion(expr.span, help, suggestion, applicability); |
| } |
| } |
| |
| fn suggest_first_deref_field( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| expr: &hir::Expr, |
| base: &hir::Expr, |
| field: ast::Ident, |
| ) { |
| let base = self.tcx.sess.source_map() |
| .span_to_snippet(base.span) |
| .unwrap_or_else(|_| self.tcx.hir().hir_to_pretty_string(base.hir_id)); |
| let msg = format!("`{}` is a raw pointer; try dereferencing it", base); |
| let suggestion = format!("(*{}).{}", base, field); |
| err.span_suggestion( |
| expr.span, |
| &msg, |
| suggestion, |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| |
| fn no_such_field_err<T: Display>(&self, span: Span, field: T, expr_t: &ty::TyS<'_>) |
| -> DiagnosticBuilder<'_> { |
| type_error_struct!(self.tcx().sess, span, expr_t, E0609, |
| "no field `{}` on type `{}`", |
| field, expr_t) |
| } |
| |
| fn check_expr_index( |
| &self, |
| base: &'tcx hir::Expr, |
| idx: &'tcx hir::Expr, |
| needs: Needs, |
| expr: &'tcx hir::Expr, |
| ) -> Ty<'tcx> { |
| 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!(self.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.kind { |
| 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.kind { |
| if let ast::LitKind::Int(i, ast::LitIntType::Unsuffixed) = lit.node { |
| let snip = self.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 |
| } |
| } |
| } |
| } |
| |
| fn check_expr_yield( |
| &self, |
| value: &'tcx hir::Expr, |
| expr: &'tcx hir::Expr, |
| src: &'tcx hir::YieldSource |
| ) -> Ty<'tcx> { |
| match self.yield_ty { |
| Some(ty) => { |
| self.check_expr_coercable_to_type(&value, ty); |
| } |
| // Given that this `yield` expression was generated as a result of lowering a `.await`, |
| // we know that the yield type must be `()`; however, the context won't contain this |
| // information. Hence, we check the source of the yield expression here and check its |
| // value's type against `()` (this check should always hold). |
| None if src == &hir::YieldSource::Await => { |
| self.check_expr_coercable_to_type(&value, self.tcx.mk_unit()); |
| } |
| _ => { |
| struct_span_err!(self.tcx.sess, expr.span, E0627, |
| "yield statement outside of generator literal").emit(); |
| } |
| } |
| self.tcx.mk_unit() |
| } |
| } |
| |
| pub(super) fn ty_kind_suggestion(ty: Ty<'_>) -> Option<&'static str> { |
| Some(match ty.kind { |
| ty::Bool => "true", |
| ty::Char => "'a'", |
| ty::Int(_) | ty::Uint(_) => "42", |
| ty::Float(_) => "3.14159", |
| ty::Error | ty::Never => return None, |
| _ => "value", |
| }) |
| } |
