diff options
| -rw-r--r-- | src/librustc_typeck/check/expr.rs | 1537 | ||||
| -rw-r--r-- | src/librustc_typeck/check/mod.rs | 1387 | ||||
| -rw-r--r-- | src/librustc_typeck/lib.rs | 1 |
3 files changed, 1543 insertions, 1382 deletions
diff --git a/src/librustc_typeck/check/expr.rs b/src/librustc_typeck/check/expr.rs new file mode 100644 index 00000000000..fa9e0d8a857 --- /dev/null +++ b/src/librustc_typeck/check/expr.rs @@ -0,0 +1,1537 @@ +//! 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::SelfSource; +use crate::middle::lang_items; +use crate::util::common::ErrorReported; +use crate::util::nodemap::FxHashMap; +use crate::astconv::AstConv as _; + +use errors::{Applicability, DiagnosticBuilder}; +use syntax::ast; +use syntax::ptr::P; +use syntax::symbol::{Symbol, LocalInternedString, 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::{CtorKind, Res, DefKind}; +use rustc::infer; +use rustc::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; +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 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>, + ) -> Ty<'tcx> { + self.check_expr_meets_expectation_or_error(expr, ExpectHasType(expected)) + } + + fn check_expr_meets_expectation_or_error( + &self, + expr: &'tcx hir::Expr, + expected: Expectation<'tcx>, + ) -> 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 = match &expr.node { + ExprKind::DropTemps(expr) => expr, + _ => expr, + }; + // 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); + + // Warn for expressions after diverging siblings. + 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.node { + ExprKind::Block(..) | + ExprKind::Loop(..) | ExprKind::While(..) | + ExprKind::Match(..) => {} + + _ => 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); + } + + // 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().hir_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.node { + 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(mutbl, ref oprnd) => { + self.check_expr_addr_of(mutbl, oprnd, expected, expr) + } + ExprKind::Path(ref qpath) => { + self.check_expr_path(qpath, expr) + } + 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) => { + self.check_expr_break(destination, expr_opt.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.deref(), expr) + } + ExprKind::Assign(ref lhs, ref rhs) => { + self.check_expr_assign(expr, expected, lhs, rhs) + } + ExprKind::While(ref cond, ref body, _) => { + self.check_expr_while(cond, body, expr) + } + 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) => { + self.check_expr_yield(value, expr) + } + 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.sty { + 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].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 + } + + fn check_expr_addr_of( + &self, + 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.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() { + self.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)); + self.tcx.mk_ref(region, tm) + } + } + + 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.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 + } + + 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 = { + 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 + } + } + + 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::ReturnType(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_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_while( + &self, + cond: &'tcx hir::Expr, + body: &'tcx hir::Block, + expr: &'tcx hir::Expr + ) -> Ty<'tcx> { + 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, self.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() + } + + 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::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_method_error(span, + rcvr_t, + segment.ident, + SelfSource::MethodCall(rcvr), + error, + Some(args)); + } + Err(()) + } + }; + + // Call the generic checker. + self.check_method_argument_types(span, + expr.span, + method, + &args[1..], + DontTupleArguments, + expected) + } + + 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.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, + }) + }; + 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_from_hir_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.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 = 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 + } + } + + 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_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 = 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.sty { + 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.sty { + &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); + } + + 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 `{}`", + if remaining_fields.len() == 1 { "" } else { "s" }, + 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, + ) { + if variant.recovered { + return; + } + let mut err = self.type_error_struct_with_diag( + field.ident.span, + |actual| match ty.sty { + 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); + // prevent all specified fields from being suggested + let skip_fields = skip_fields.iter().map(|ref x| x.ident.as_str()); + 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.sty { + 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<LocalInternedString>) + -> 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.as_str()) || + (!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.sty { + 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 { + let struct_path = self.tcx().def_path_str(did); + let mut err = struct_span_err!(self.tcx().sess, expr.span, E0616, + "field `{}` of struct `{}` is private", + field, 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(); + field_ty + } else if field.name == kw::Invalid { + self.tcx().types.err + } else if self.method_exists(field, expr_t, expr.hir_id, true) { + 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(); + self.tcx().types.err + } else { + if !expr_t.is_primitive_ty() { + let mut err = self.no_such_field_err(field.span, field, expr_t); + + match expr_t.sty { + ty::Adt(def, _) if !def.is_enum() => { + 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))); + } + }; + } + ty::Array(_, len) => { + if let (Some(len), Ok(user_index)) = ( + len.assert_usize(self.tcx), + 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 + ); + } + } + ty::RawPtr(..) => { + 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, + ); + } + _ => {} + } + err + } 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 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.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 = 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) -> Ty<'tcx> { + 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(); + } + } + self.tcx.mk_unit() + } +} diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs index 22f17097fcb..ecf7860367b 100644 --- a/src/librustc_typeck/check/mod.rs +++ b/src/librustc_typeck/check/mod.rs @@ -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; @@ -105,7 +106,7 @@ use rustc::middle::region; use rustc::mir::interpret::{ConstValue, GlobalId}; use rustc::traits::{self, ObligationCause, ObligationCauseCode, TraitEngine}; use rustc::ty::{ - self, AdtKind, CanonicalUserType, Ty, TyCtxt, Const, GenericParamDefKind, Visibility, + self, AdtKind, CanonicalUserType, Ty, TyCtxt, Const, GenericParamDefKind, ToPolyTraitRef, ToPredicate, RegionKind, UserType }; use rustc::ty::adjustment::{ @@ -123,13 +124,11 @@ use syntax::attr; use syntax::feature_gate::{GateIssue, emit_feature_err}; use syntax::ptr::P; use syntax::source_map::{DUMMY_SP, original_sp}; -use syntax::symbol::{Symbol, LocalInternedString, kw, sym}; -use syntax::util::lev_distance::find_best_match_for_name; +use syntax::symbol::{kw, sym}; use std::cell::{Cell, RefCell, Ref, RefMut}; use std::collections::hash_map::Entry; use std::cmp; -use std::fmt::Display; use std::iter; use std::mem::replace; use std::ops::{self, Deref}; @@ -142,7 +141,7 @@ use crate::TypeAndSubsts; use crate::lint; use crate::util::captures::Captures; use crate::util::common::{ErrorReported, indenter}; -use crate::util::nodemap::{DefIdMap, DefIdSet, FxHashMap, FxHashSet, HirIdMap}; +use crate::util::nodemap::{DefIdMap, DefIdSet, FxHashSet, HirIdMap}; pub use self::Expectation::*; use self::autoderef::Autoderef; @@ -3196,82 +3195,6 @@ 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>, - ) -> Ty<'tcx> { - self.check_expr_meets_expectation_or_error(expr, ExpectHasType(expected)) - } - - fn check_expr_meets_expectation_or_error( - &self, - expr: &'tcx hir::Expr, - expected: Expectation<'tcx>, - ) -> 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 = match &expr.node { - ExprKind::DropTemps(expr) => expr, - _ => expr, - }; - // Error possibly reported in `check_assign` so avoid emitting error again. - err.emit_unless(self.is_assign_to_bool(expr, expected_ty)); - } - ty - } - - 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) - } - - fn check_expr_with_hint(&self, expr: &'tcx hir::Expr, expected: Ty<'tcx>) -> Ty<'tcx> { - self.check_expr_with_expectation(expr, ExpectHasType(expected)) - } - - 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) - } - - fn check_expr(&self, expr: &'tcx hir::Expr) -> Ty<'tcx> { - self.check_expr_with_expectation(expr, NoExpectation) - } - - fn check_expr_with_needs(&self, expr: &'tcx hir::Expr, needs: Needs) -> Ty<'tcx> { - self.check_expr_with_expectation_and_needs(expr, NoExpectation, needs) - } - // Determine the `Self` type, using fresh variables for all variables // declared on the impl declaration e.g., `impl<A,B> for Vec<(A,B)>` // would return `($0, $1)` where `$0` and `$1` are freshly instantiated type @@ -3341,470 +3264,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { expect_args } - // 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_method_error(span, - rcvr_t, - segment.ident, - SelfSource::MethodCall(rcvr), - error, - Some(args)); - } - Err(()) - } - }; - - // Call the generic checker. - self.check_method_argument_types(span, - expr.span, - method, - &args[1..], - DontTupleArguments, - expected) - } - - 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::ReturnType(return_expr.hir_id)), - return_expr, - return_expr_ty); - } - - // 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.sty { - 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 { - let struct_path = self.tcx().def_path_str(did); - let mut err = struct_span_err!(self.tcx().sess, expr.span, E0616, - "field `{}` of struct `{}` is private", - field, 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(); - field_ty - } else if field.name == kw::Invalid { - self.tcx().types.err - } else if self.method_exists(field, expr_t, expr.hir_id, true) { - 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(); - self.tcx().types.err - } else { - if !expr_t.is_primitive_ty() { - let mut err = self.no_such_field_err(field.span, field, expr_t); - - match expr_t.sty { - ty::Adt(def, _) if !def.is_enum() => { - 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))); - } - }; - } - ty::Array(_, len) => { - if let (Some(len), Ok(user_index)) = ( - len.assert_usize(self.tcx), - 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 - ); - } - } - ty::RawPtr(..) => { - 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, - ); - } - _ => {} - } - err - } 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 - } - } - - // Return an hint about the closest match in field names - fn suggest_field_name(variant: &'tcx ty::VariantDef, - field: &str, - skip: Vec<LocalInternedString>) - -> 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.as_str()) || - (!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 - } - - 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 report_unknown_field( - &self, - ty: Ty<'tcx>, - variant: &'tcx ty::VariantDef, - field: &hir::Field, - skip_fields: &[hir::Field], - kind_name: &str, - ) { - if variant.recovered { - return; - } - let mut err = self.type_error_struct_with_diag( - field.ident.span, - |actual| match ty.sty { - 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); - // prevent all specified fields from being suggested - let skip_fields = skip_fields.iter().map(|ref x| x.ident.as_str()); - 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.sty { - 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(); - } - - 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.sty { - &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); - } - - 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 `{}`", - if remaining_fields.len() == 1 { "" } else { "s" }, - 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); - } - } - pub fn check_struct_path(&self, qpath: &QPath, hir_id: hir::HirId) @@ -3863,842 +3322,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } } - 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.sty { - 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 - } - - - /// 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); - - // Warn for expressions after diverging siblings. - 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.node { - ExprKind::Block(..) | - ExprKind::Loop(..) | ExprKind::While(..) | - ExprKind::Match(..) => {} - - _ => 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); - } - - // 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().hir_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; - 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( - &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_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() - } - } - // Finish resolving a path in a struct expression or pattern `S::A { .. }` if necessary. // The newly resolved definition is written into `type_dependent_defs`. fn finish_resolving_struct_path(&self, diff --git a/src/librustc_typeck/lib.rs b/src/librustc_typeck/lib.rs index 79674e4baeb..cc6f7a07d96 100644 --- a/src/librustc_typeck/lib.rs +++ b/src/librustc_typeck/lib.rs @@ -68,6 +68,7 @@ This API is completely unstable and subject to change. #![feature(rustc_diagnostic_macros)] #![feature(slice_patterns)] #![feature(never_type)] +#![feature(inner_deref)] #![recursion_limit="256"] |