| // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| use hir::def::Def; |
| use rustc::infer::{self, InferOk, TypeOrigin}; |
| use hir::pat_util::EnumerateAndAdjustIterator; |
| use rustc::ty::subst::Substs; |
| use rustc::ty::{self, Ty, TypeFoldable, LvaluePreference, VariantKind}; |
| use check::{FnCtxt, Expectation}; |
| use lint; |
| use util::nodemap::FnvHashMap; |
| |
| use std::collections::hash_map::Entry::{Occupied, Vacant}; |
| use std::cmp; |
| use syntax::ast; |
| use syntax::codemap::Spanned; |
| use syntax::ptr::P; |
| use syntax_pos::Span; |
| |
| use rustc::hir::{self, PatKind}; |
| use rustc::hir::print as pprust; |
| |
| impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> { |
| pub fn check_pat(&self, pat: &'gcx hir::Pat, expected: Ty<'tcx>) { |
| let tcx = self.tcx; |
| |
| debug!("check_pat(pat={:?},expected={:?})", pat, expected); |
| |
| match pat.node { |
| PatKind::Wild => { |
| self.write_ty(pat.id, expected); |
| } |
| PatKind::Lit(ref lt) => { |
| self.check_expr(<); |
| let expr_ty = self.expr_ty(<); |
| |
| // Byte string patterns behave the same way as array patterns |
| // They can denote both statically and dynamically sized byte arrays |
| let mut pat_ty = expr_ty; |
| if let hir::ExprLit(ref lt) = lt.node { |
| if let ast::LitKind::ByteStr(_) = lt.node { |
| let expected_ty = self.structurally_resolved_type(pat.span, expected); |
| if let ty::TyRef(_, mt) = expected_ty.sty { |
| if let ty::TySlice(_) = mt.ty.sty { |
| pat_ty = tcx.mk_imm_ref(tcx.mk_region(ty::ReStatic), |
| tcx.mk_slice(tcx.types.u8)) |
| } |
| } |
| } |
| } |
| |
| self.write_ty(pat.id, pat_ty); |
| |
| // somewhat surprising: in this case, the subtyping |
| // relation goes the opposite way as the other |
| // cases. Actually what we really want is not a subtyping |
| // relation at all but rather that there exists a LUB (so |
| // that they can be compared). However, in practice, |
| // constants are always scalars or strings. For scalars |
| // subtyping is irrelevant, and for strings `expr_ty` is |
| // type is `&'static str`, so if we say that |
| // |
| // &'static str <: expected |
| // |
| // that's equivalent to there existing a LUB. |
| self.demand_suptype(pat.span, expected, pat_ty); |
| } |
| PatKind::Range(ref begin, ref end) => { |
| self.check_expr(begin); |
| self.check_expr(end); |
| |
| let lhs_ty = self.expr_ty(begin); |
| let rhs_ty = self.expr_ty(end); |
| |
| // Check that both end-points are of numeric or char type. |
| let numeric_or_char = |ty: Ty| ty.is_numeric() || ty.is_char(); |
| let lhs_compat = numeric_or_char(lhs_ty); |
| let rhs_compat = numeric_or_char(rhs_ty); |
| |
| if !lhs_compat || !rhs_compat { |
| let span = if !lhs_compat && !rhs_compat { |
| pat.span |
| } else if !lhs_compat { |
| begin.span |
| } else { |
| end.span |
| }; |
| |
| // Note: spacing here is intentional, we want a space before "start" and "end". |
| span_err!(tcx.sess, span, E0029, |
| "only char and numeric types are allowed in range patterns\n \ |
| start type: {}\n end type: {}", |
| self.ty_to_string(lhs_ty), |
| self.ty_to_string(rhs_ty) |
| ); |
| return; |
| } |
| |
| // Now that we know the types can be unified we find the unified type and use |
| // it to type the entire expression. |
| let common_type = self.resolve_type_vars_if_possible(&lhs_ty); |
| |
| self.write_ty(pat.id, common_type); |
| |
| // subtyping doesn't matter here, as the value is some kind of scalar |
| self.demand_eqtype(pat.span, expected, lhs_ty); |
| self.demand_eqtype(pat.span, expected, rhs_ty); |
| } |
| PatKind::Binding(bm, _, ref sub) => { |
| let typ = self.local_ty(pat.span, pat.id); |
| match bm { |
| hir::BindByRef(mutbl) => { |
| // if the binding is like |
| // ref x | ref const x | ref mut x |
| // then `x` is assigned a value of type `&M T` where M is the mutability |
| // and T is the expected type. |
| let region_var = self.next_region_var(infer::PatternRegion(pat.span)); |
| let mt = ty::TypeAndMut { ty: expected, mutbl: mutbl }; |
| let region_ty = tcx.mk_ref(tcx.mk_region(region_var), mt); |
| |
| // `x` is assigned a value of type `&M T`, hence `&M T <: typeof(x)` is |
| // required. However, we use equality, which is stronger. See (*) for |
| // an explanation. |
| self.demand_eqtype(pat.span, region_ty, typ); |
| } |
| // otherwise the type of x is the expected type T |
| hir::BindByValue(_) => { |
| // As above, `T <: typeof(x)` is required but we |
| // use equality, see (*) below. |
| self.demand_eqtype(pat.span, expected, typ); |
| } |
| } |
| |
| self.write_ty(pat.id, typ); |
| |
| // if there are multiple arms, make sure they all agree on |
| // what the type of the binding `x` ought to be |
| match tcx.expect_def(pat.id) { |
| Def::Err => {} |
| Def::Local(_, var_id) => { |
| if var_id != pat.id { |
| let vt = self.local_ty(pat.span, var_id); |
| self.demand_eqtype(pat.span, vt, typ); |
| } |
| } |
| d => bug!("bad def for pattern binding `{:?}`", d) |
| } |
| |
| if let Some(ref p) = *sub { |
| self.check_pat(&p, expected); |
| } |
| } |
| PatKind::TupleStruct(ref path, ref subpats, ddpos) => { |
| self.check_pat_tuple_struct(pat, path, &subpats, ddpos, expected); |
| } |
| PatKind::Path(ref opt_qself, ref path) => { |
| let opt_qself_ty = opt_qself.as_ref().map(|qself| self.to_ty(&qself.ty)); |
| self.check_pat_path(pat, opt_qself_ty, path, expected); |
| } |
| PatKind::Struct(ref path, ref fields, etc) => { |
| self.check_pat_struct(pat, path, fields, etc, expected); |
| } |
| PatKind::Tuple(ref elements, ddpos) => { |
| let mut expected_len = elements.len(); |
| if ddpos.is_some() { |
| // Require known type only when `..` is present |
| if let ty::TyTuple(ref tys) = |
| self.structurally_resolved_type(pat.span, expected).sty { |
| expected_len = tys.len(); |
| } |
| } |
| let max_len = cmp::max(expected_len, elements.len()); |
| |
| let element_tys: Vec<_> = (0 .. max_len).map(|_| self.next_ty_var()).collect(); |
| let pat_ty = tcx.mk_tup(element_tys.clone()); |
| self.write_ty(pat.id, pat_ty); |
| self.demand_eqtype(pat.span, expected, pat_ty); |
| for (i, elem) in elements.iter().enumerate_and_adjust(max_len, ddpos) { |
| self.check_pat(elem, &element_tys[i]); |
| } |
| } |
| PatKind::Box(ref inner) => { |
| let inner_ty = self.next_ty_var(); |
| let uniq_ty = tcx.mk_box(inner_ty); |
| |
| if self.check_dereferencable(pat.span, expected, &inner) { |
| // Here, `demand::subtype` is good enough, but I don't |
| // think any errors can be introduced by using |
| // `demand::eqtype`. |
| self.demand_eqtype(pat.span, expected, uniq_ty); |
| self.write_ty(pat.id, uniq_ty); |
| self.check_pat(&inner, inner_ty); |
| } else { |
| self.write_error(pat.id); |
| self.check_pat(&inner, tcx.types.err); |
| } |
| } |
| PatKind::Ref(ref inner, mutbl) => { |
| let expected = self.shallow_resolve(expected); |
| if self.check_dereferencable(pat.span, expected, &inner) { |
| // `demand::subtype` would be good enough, but using |
| // `eqtype` turns out to be equally general. See (*) |
| // below for details. |
| |
| // Take region, inner-type from expected type if we |
| // can, to avoid creating needless variables. This |
| // also helps with the bad interactions of the given |
| // hack detailed in (*) below. |
| let (rptr_ty, inner_ty) = match expected.sty { |
| ty::TyRef(_, mt) if mt.mutbl == mutbl => { |
| (expected, mt.ty) |
| } |
| _ => { |
| let inner_ty = self.next_ty_var(); |
| let mt = ty::TypeAndMut { ty: inner_ty, mutbl: mutbl }; |
| let region = self.next_region_var(infer::PatternRegion(pat.span)); |
| let rptr_ty = tcx.mk_ref(tcx.mk_region(region), mt); |
| self.demand_eqtype(pat.span, expected, rptr_ty); |
| (rptr_ty, inner_ty) |
| } |
| }; |
| |
| self.write_ty(pat.id, rptr_ty); |
| self.check_pat(&inner, inner_ty); |
| } else { |
| self.write_error(pat.id); |
| self.check_pat(&inner, tcx.types.err); |
| } |
| } |
| PatKind::Vec(ref before, ref slice, ref after) => { |
| let expected_ty = self.structurally_resolved_type(pat.span, expected); |
| let (inner_ty, slice_ty) = match expected_ty.sty { |
| ty::TyArray(inner_ty, size) => { |
| let min_len = before.len() + after.len(); |
| if slice.is_none() { |
| if min_len != size { |
| span_err!(tcx.sess, pat.span, E0527, |
| "pattern requires {} elements but array has {}", |
| min_len, size); |
| } |
| (inner_ty, tcx.types.err) |
| } else if let Some(rest) = size.checked_sub(min_len) { |
| (inner_ty, tcx.mk_array(inner_ty, rest)) |
| } else { |
| span_err!(tcx.sess, pat.span, E0528, |
| "pattern requires at least {} elements but array has {}", |
| min_len, size); |
| (inner_ty, tcx.types.err) |
| } |
| } |
| ty::TySlice(inner_ty) => (inner_ty, expected_ty), |
| _ => { |
| if !expected_ty.references_error() { |
| let mut err = struct_span_err!( |
| tcx.sess, pat.span, E0529, |
| "expected an array or slice, found `{}`", |
| expected_ty); |
| if let ty::TyRef(_, ty::TypeAndMut { mutbl: _, ty }) = expected_ty.sty { |
| match ty.sty { |
| ty::TyArray(..) | ty::TySlice(..) => { |
| err.help("the semantics of slice patterns changed \ |
| recently; see issue #23121"); |
| } |
| _ => {} |
| } |
| } |
| err.emit(); |
| } |
| (tcx.types.err, tcx.types.err) |
| } |
| }; |
| |
| self.write_ty(pat.id, expected_ty); |
| |
| for elt in before { |
| self.check_pat(&elt, inner_ty); |
| } |
| if let Some(ref slice) = *slice { |
| self.check_pat(&slice, slice_ty); |
| } |
| for elt in after { |
| self.check_pat(&elt, inner_ty); |
| } |
| } |
| } |
| |
| // (*) In most of the cases above (literals and constants being |
| // the exception), we relate types using strict equality, evewn |
| // though subtyping would be sufficient. There are a few reasons |
| // for this, some of which are fairly subtle and which cost me |
| // (nmatsakis) an hour or two debugging to remember, so I thought |
| // I'd write them down this time. |
| // |
| // 1. There is no loss of expressiveness here, though it does |
| // cause some inconvenience. What we are saying is that the type |
| // of `x` becomes *exactly* what is expected. This can cause unnecessary |
| // errors in some cases, such as this one: |
| // it will cause errors in a case like this: |
| // |
| // ``` |
| // fn foo<'x>(x: &'x int) { |
| // let a = 1; |
| // let mut z = x; |
| // z = &a; |
| // } |
| // ``` |
| // |
| // The reason we might get an error is that `z` might be |
| // assigned a type like `&'x int`, and then we would have |
| // a problem when we try to assign `&a` to `z`, because |
| // the lifetime of `&a` (i.e., the enclosing block) is |
| // shorter than `'x`. |
| // |
| // HOWEVER, this code works fine. The reason is that the |
| // expected type here is whatever type the user wrote, not |
| // the initializer's type. In this case the user wrote |
| // nothing, so we are going to create a type variable `Z`. |
| // Then we will assign the type of the initializer (`&'x |
| // int`) as a subtype of `Z`: `&'x int <: Z`. And hence we |
| // will instantiate `Z` as a type `&'0 int` where `'0` is |
| // a fresh region variable, with the constraint that `'x : |
| // '0`. So basically we're all set. |
| // |
| // Note that there are two tests to check that this remains true |
| // (`regions-reassign-{match,let}-bound-pointer.rs`). |
| // |
| // 2. Things go horribly wrong if we use subtype. The reason for |
| // THIS is a fairly subtle case involving bound regions. See the |
| // `givens` field in `region_inference`, as well as the test |
| // `regions-relate-bound-regions-on-closures-to-inference-variables.rs`, |
| // for details. Short version is that we must sometimes detect |
| // relationships between specific region variables and regions |
| // bound in a closure signature, and that detection gets thrown |
| // off when we substitute fresh region variables here to enable |
| // subtyping. |
| } |
| |
| pub fn check_dereferencable(&self, span: Span, expected: Ty<'tcx>, inner: &hir::Pat) -> bool { |
| if let PatKind::Binding(..) = inner.node { |
| if let Some(mt) = self.shallow_resolve(expected).builtin_deref(true, ty::NoPreference) { |
| if let ty::TyTrait(..) = mt.ty.sty { |
| // This is "x = SomeTrait" being reduced from |
| // "let &x = &SomeTrait" or "let box x = Box<SomeTrait>", an error. |
| span_err!(self.tcx.sess, span, E0033, |
| "type `{}` cannot be dereferenced", |
| self.ty_to_string(expected)); |
| return false |
| } |
| } |
| } |
| true |
| } |
| } |
| |
| impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> { |
| pub fn check_match(&self, |
| expr: &'gcx hir::Expr, |
| discrim: &'gcx hir::Expr, |
| arms: &'gcx [hir::Arm], |
| expected: Expectation<'tcx>, |
| match_src: hir::MatchSource) { |
| let tcx = self.tcx; |
| |
| // Not entirely obvious: if matches may create ref bindings, we |
| // want to use the *precise* type of the discriminant, *not* some |
| // supertype, as the "discriminant type" (issue #23116). |
| let contains_ref_bindings = arms.iter() |
| .filter_map(|a| tcx.arm_contains_ref_binding(a)) |
| .max_by_key(|m| match *m { |
| hir::MutMutable => 1, |
| hir::MutImmutable => 0, |
| }); |
| let discrim_ty; |
| if let Some(m) = contains_ref_bindings { |
| self.check_expr_with_lvalue_pref(discrim, LvaluePreference::from_mutbl(m)); |
| discrim_ty = self.expr_ty(discrim); |
| } else { |
| // ...but otherwise we want to use any supertype of the |
| // discriminant. This is sort of a workaround, see note (*) in |
| // `check_pat` for some details. |
| discrim_ty = self.next_ty_var(); |
| self.check_expr_has_type(discrim, discrim_ty); |
| }; |
| |
| // Typecheck the patterns first, so that we get types for all the |
| // bindings. |
| for arm in arms { |
| for p in &arm.pats { |
| self.check_pat(&p, discrim_ty); |
| } |
| } |
| |
| // Now typecheck the blocks. |
| // |
| // The result of the match is the common supertype of all the |
| // arms. Start out the value as bottom, since it's the, well, |
| // bottom the type lattice, and we'll be moving up the lattice as |
| // we process each arm. (Note that any match with 0 arms is matching |
| // on any empty type and is therefore unreachable; should the flow |
| // of execution reach it, we will panic, so bottom is an appropriate |
| // type in that case) |
| let expected = expected.adjust_for_branches(self); |
| let mut result_ty = self.next_diverging_ty_var(); |
| let coerce_first = match expected { |
| // We don't coerce to `()` so that if the match expression is a |
| // statement it's branches can have any consistent type. That allows |
| // us to give better error messages (pointing to a usually better |
| // arm for inconsistent arms or to the whole match when a `()` type |
| // is required). |
| Expectation::ExpectHasType(ety) if ety != self.tcx.mk_nil() => { |
| ety |
| } |
| _ => result_ty |
| }; |
| for (i, arm) in arms.iter().enumerate() { |
| if let Some(ref e) = arm.guard { |
| self.check_expr_has_type(e, tcx.types.bool); |
| } |
| self.check_expr_with_expectation(&arm.body, expected); |
| let arm_ty = self.expr_ty(&arm.body); |
| |
| if result_ty.references_error() || arm_ty.references_error() { |
| result_ty = tcx.types.err; |
| continue; |
| } |
| |
| // Handle the fallback arm of a desugared if-let like a missing else. |
| let is_if_let_fallback = match match_src { |
| hir::MatchSource::IfLetDesugar { contains_else_clause: false } => { |
| i == arms.len() - 1 && arm_ty.is_nil() |
| } |
| _ => false |
| }; |
| |
| let origin = if is_if_let_fallback { |
| TypeOrigin::IfExpressionWithNoElse(expr.span) |
| } else { |
| TypeOrigin::MatchExpressionArm(expr.span, arm.body.span, match_src) |
| }; |
| |
| let result = if is_if_let_fallback { |
| self.eq_types(true, origin, arm_ty, result_ty) |
| .map(|InferOk { obligations, .. }| { |
| // FIXME(#32730) propagate obligations |
| assert!(obligations.is_empty()); |
| arm_ty |
| }) |
| } else if i == 0 { |
| // Special-case the first arm, as it has no "previous expressions". |
| self.try_coerce(&arm.body, coerce_first) |
| } else { |
| let prev_arms = || arms[..i].iter().map(|arm| &*arm.body); |
| self.try_find_coercion_lub(origin, prev_arms, result_ty, &arm.body) |
| }; |
| |
| result_ty = match result { |
| Ok(ty) => ty, |
| Err(e) => { |
| let (expected, found) = if is_if_let_fallback { |
| (arm_ty, result_ty) |
| } else { |
| (result_ty, arm_ty) |
| }; |
| self.report_mismatched_types(origin, expected, found, e); |
| self.tcx.types.err |
| } |
| }; |
| } |
| |
| self.write_ty(expr.id, result_ty); |
| } |
| } |
| |
| impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> { |
| fn check_pat_struct(&self, |
| pat: &'gcx hir::Pat, |
| path: &hir::Path, |
| fields: &'gcx [Spanned<hir::FieldPat>], |
| etc: bool, |
| expected: Ty<'tcx>) |
| { |
| // Resolve the path and check the definition for errors. |
| let (variant, pat_ty) = if let Some(variant_ty) = self.check_struct_path(path, pat.id, |
| pat.span) { |
| variant_ty |
| } else { |
| self.write_error(pat.id); |
| for field in fields { |
| self.check_pat(&field.node.pat, self.tcx.types.err); |
| } |
| return; |
| }; |
| |
| // Type check the path. |
| self.demand_eqtype(pat.span, expected, pat_ty); |
| |
| // Type check subpatterns. |
| let substs = match pat_ty.sty { |
| ty::TyStruct(_, substs) | ty::TyEnum(_, substs) => substs, |
| _ => span_bug!(pat.span, "struct variant is not an ADT") |
| }; |
| self.check_struct_pat_fields(pat.span, fields, variant, substs, etc); |
| } |
| |
| fn check_pat_path(&self, |
| pat: &hir::Pat, |
| opt_self_ty: Option<Ty<'tcx>>, |
| path: &hir::Path, |
| expected: Ty<'tcx>) |
| { |
| let tcx = self.tcx; |
| let report_unexpected_def = || { |
| span_err!(tcx.sess, pat.span, E0533, |
| "`{}` does not name a unit variant, unit struct or a constant", |
| pprust::path_to_string(path)); |
| self.write_error(pat.id); |
| }; |
| |
| // Resolve the path and check the definition for errors. |
| let (def, opt_ty, segments) = self.resolve_ty_and_def_ufcs(opt_self_ty, path, |
| pat.id, pat.span); |
| match def { |
| Def::Err => { |
| self.set_tainted_by_errors(); |
| self.write_error(pat.id); |
| return; |
| } |
| Def::Method(..) => { |
| report_unexpected_def(); |
| return; |
| } |
| Def::Variant(..) | Def::Struct(..) => { |
| let variant = tcx.expect_variant_def(def); |
| if variant.kind != VariantKind::Unit { |
| report_unexpected_def(); |
| return; |
| } |
| } |
| Def::Const(..) | Def::AssociatedConst(..) => {} // OK |
| _ => bug!("unexpected pattern definition {:?}", def) |
| } |
| |
| // Type check the path. |
| let scheme = tcx.lookup_item_type(def.def_id()); |
| let predicates = tcx.lookup_predicates(def.def_id()); |
| let pat_ty = self.instantiate_value_path(segments, scheme, &predicates, |
| opt_ty, def, pat.span, pat.id); |
| self.demand_suptype(pat.span, expected, pat_ty); |
| } |
| |
| fn check_pat_tuple_struct(&self, |
| pat: &hir::Pat, |
| path: &hir::Path, |
| subpats: &'gcx [P<hir::Pat>], |
| ddpos: Option<usize>, |
| expected: Ty<'tcx>) |
| { |
| let tcx = self.tcx; |
| let on_error = || { |
| self.write_error(pat.id); |
| for pat in subpats { |
| self.check_pat(&pat, tcx.types.err); |
| } |
| }; |
| let report_unexpected_def = |is_lint| { |
| let msg = format!("`{}` does not name a tuple variant or a tuple struct", |
| pprust::path_to_string(path)); |
| if is_lint { |
| tcx.sess.add_lint(lint::builtin::MATCH_OF_UNIT_VARIANT_VIA_PAREN_DOTDOT, |
| pat.id, pat.span, msg); |
| } else { |
| span_err!(tcx.sess, pat.span, E0164, "{}", msg); |
| on_error(); |
| } |
| }; |
| |
| // Resolve the path and check the definition for errors. |
| let (def, opt_ty, segments) = self.resolve_ty_and_def_ufcs(None, path, pat.id, pat.span); |
| let variant = match def { |
| Def::Err => { |
| self.set_tainted_by_errors(); |
| on_error(); |
| return; |
| } |
| Def::Const(..) | Def::AssociatedConst(..) | Def::Method(..) => { |
| report_unexpected_def(false); |
| return; |
| } |
| Def::Variant(..) | Def::Struct(..) => { |
| tcx.expect_variant_def(def) |
| } |
| _ => bug!("unexpected pattern definition {:?}", def) |
| }; |
| if variant.kind == VariantKind::Unit && subpats.is_empty() && ddpos.is_some() { |
| // Matching unit structs with tuple variant patterns (`UnitVariant(..)`) |
| // is allowed for backward compatibility. |
| report_unexpected_def(true); |
| } else if variant.kind != VariantKind::Tuple { |
| report_unexpected_def(false); |
| return; |
| } |
| |
| // Type check the path. |
| let scheme = tcx.lookup_item_type(def.def_id()); |
| let scheme = if scheme.ty.is_fn() { |
| // Replace constructor type with constructed type for tuple struct patterns. |
| let fn_ret = tcx.no_late_bound_regions(&scheme.ty.fn_ret()).unwrap().unwrap(); |
| ty::TypeScheme { ty: fn_ret, generics: scheme.generics } |
| } else { |
| // Leave the type as is for unit structs (backward compatibility). |
| scheme |
| }; |
| let predicates = tcx.lookup_predicates(def.def_id()); |
| let pat_ty = self.instantiate_value_path(segments, scheme, &predicates, |
| opt_ty, def, pat.span, pat.id); |
| self.demand_eqtype(pat.span, expected, pat_ty); |
| |
| // Type check subpatterns. |
| if subpats.len() == variant.fields.len() || |
| subpats.len() < variant.fields.len() && ddpos.is_some() { |
| let substs = match pat_ty.sty { |
| ty::TyStruct(_, substs) | ty::TyEnum(_, substs) => substs, |
| ref ty => bug!("unexpected pattern type {:?}", ty), |
| }; |
| for (i, subpat) in subpats.iter().enumerate_and_adjust(variant.fields.len(), ddpos) { |
| let field_ty = self.field_ty(subpat.span, &variant.fields[i], substs); |
| self.check_pat(&subpat, field_ty); |
| } |
| } else { |
| span_err!(tcx.sess, pat.span, E0023, |
| "this pattern has {} field{s}, but the corresponding {} has {} field{s}", |
| subpats.len(), def.kind_name(), variant.fields.len(), |
| s = if variant.fields.len() == 1 {""} else {"s"}); |
| on_error(); |
| } |
| } |
| |
| /// `path` is the AST path item naming the type of this struct. |
| /// `fields` is the field patterns of the struct pattern. |
| /// `struct_fields` describes the type of each field of the struct. |
| /// `struct_id` is the ID of the struct. |
| /// `etc` is true if the pattern said '...' and false otherwise. |
| pub fn check_struct_pat_fields(&self, |
| span: Span, |
| fields: &'gcx [Spanned<hir::FieldPat>], |
| variant: ty::VariantDef<'tcx>, |
| substs: &Substs<'tcx>, |
| etc: bool) { |
| let tcx = self.tcx; |
| |
| // Index the struct fields' types. |
| let field_map = variant.fields |
| .iter() |
| .map(|field| (field.name, field)) |
| .collect::<FnvHashMap<_, _>>(); |
| |
| // Keep track of which fields have already appeared in the pattern. |
| let mut used_fields = FnvHashMap(); |
| |
| // Typecheck each field. |
| for &Spanned { node: ref field, span } in fields { |
| let field_ty = match used_fields.entry(field.name) { |
| Occupied(occupied) => { |
| let mut err = struct_span_err!(tcx.sess, span, E0025, |
| "field `{}` bound multiple times \ |
| in the pattern", |
| field.name); |
| span_note!(&mut err, *occupied.get(), |
| "field `{}` previously bound here", |
| field.name); |
| err.emit(); |
| tcx.types.err |
| } |
| Vacant(vacant) => { |
| vacant.insert(span); |
| field_map.get(&field.name) |
| .map(|f| self.field_ty(span, f, substs)) |
| .unwrap_or_else(|| { |
| span_err!(tcx.sess, span, E0026, |
| "struct `{}` does not have a field named `{}`", |
| tcx.item_path_str(variant.did), |
| field.name); |
| tcx.types.err |
| }) |
| } |
| }; |
| |
| self.check_pat(&field.pat, field_ty); |
| } |
| |
| // Report an error if not all the fields were specified. |
| if !etc { |
| for field in variant.fields |
| .iter() |
| .filter(|field| !used_fields.contains_key(&field.name)) { |
| span_err!(tcx.sess, span, E0027, |
| "pattern does not mention field `{}`", |
| field.name); |
| } |
| } |
| } |
| } |
