From 2b7a23ed304d4298247b030eea0820018c05cd30 Mon Sep 17 00:00:00 2001 From: Andrew Cann Date: Wed, 25 Jan 2017 14:48:20 +0800 Subject: [PATCH] Hide uninhabitedness checks behind feature gate --- src/librustc/ty/inhabitedness/mod.rs | 6 +-- src/librustc_const_eval/_match.rs | 17 +++++-- src/librustc_mir/build/matches/simplify.rs | 30 ++++++----- .../uninhabited-matches-feature-gated.rs | 50 +++++++++++++++++++ ...ninhabited-reference-type-feature-gated.rs | 19 ------- 5 files changed, 81 insertions(+), 41 deletions(-) create mode 100644 src/test/compile-fail/uninhabited-matches-feature-gated.rs delete mode 100644 src/test/compile-fail/uninhabited-reference-type-feature-gated.rs diff --git a/src/librustc/ty/inhabitedness/mod.rs b/src/librustc/ty/inhabitedness/mod.rs index 92395e3c381aa..6c49493a65559 100644 --- a/src/librustc/ty/inhabitedness/mod.rs +++ b/src/librustc/ty/inhabitedness/mod.rs @@ -191,11 +191,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> { } } TyRef(_, ref tm) => { - if tcx.sess.features.borrow().never_type { - tm.ty.uninhabited_from(visited, tcx) - } else { - DefIdForest::empty() - } + tm.ty.uninhabited_from(visited, tcx) } _ => DefIdForest::empty(), diff --git a/src/librustc_const_eval/_match.rs b/src/librustc_const_eval/_match.rs index bb5dacf71e175..1770a112cdf23 100644 --- a/src/librustc_const_eval/_match.rs +++ b/src/librustc_const_eval/_match.rs @@ -379,19 +379,24 @@ impl<'tcx> Witness<'tcx> { fn all_constructors<'a, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>, pcx: PatternContext<'tcx>) -> Vec { + let check_inhabited = cx.tcx.sess.features.borrow().never_type; debug!("all_constructors({:?})", pcx.ty); match pcx.ty.sty { ty::TyBool => [true, false].iter().map(|b| ConstantValue(ConstVal::Bool(*b))).collect(), ty::TySlice(ref sub_ty) => { - if sub_ty.is_uninhabited_from(cx.module, cx.tcx) { + if sub_ty.is_uninhabited_from(cx.module, cx.tcx) + && check_inhabited + { vec![Slice(0)] } else { (0..pcx.max_slice_length+1).map(|length| Slice(length)).collect() } } ty::TyArray(ref sub_ty, length) => { - if length == 0 || !sub_ty.is_uninhabited_from(cx.module, cx.tcx) { + if length == 0 || !(sub_ty.is_uninhabited_from(cx.module, cx.tcx) + && check_inhabited) + { vec![Slice(length)] } else { vec![] @@ -403,7 +408,9 @@ fn all_constructors<'a, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>, let forest = v.uninhabited_from(&mut visited, cx.tcx, substs, AdtKind::Enum); - if forest.contains(cx.tcx, cx.module) { + if forest.contains(cx.tcx, cx.module) + && check_inhabited + { None } else { Some(Variant(v.did)) @@ -411,7 +418,9 @@ fn all_constructors<'a, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>, }).collect() } _ => { - if pcx.ty.is_uninhabited_from(cx.module, cx.tcx) { + if pcx.ty.is_uninhabited_from(cx.module, cx.tcx) + && check_inhabited + { vec![] } else { vec![Single] diff --git a/src/librustc_mir/build/matches/simplify.rs b/src/librustc_mir/build/matches/simplify.rs index b071834122367..e94d35195c213 100644 --- a/src/librustc_mir/build/matches/simplify.rs +++ b/src/librustc_mir/build/matches/simplify.rs @@ -99,20 +99,24 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> { } PatternKind::Variant { adt_def, substs, variant_index, ref subpatterns } => { - let irrefutable = adt_def.variants.iter().enumerate().all(|(i, v)| { - i == variant_index || { - let mut visited = FxHashSet::default(); - let node_set = v.uninhabited_from(&mut visited, - self.hir.tcx(), - substs, - adt_def.adt_kind()); - !node_set.is_empty() + if self.hir.tcx().sess.features.borrow().never_type { + let irrefutable = adt_def.variants.iter().enumerate().all(|(i, v)| { + i == variant_index || { + let mut visited = FxHashSet::default(); + let node_set = v.uninhabited_from(&mut visited, + self.hir.tcx(), + substs, + adt_def.adt_kind()); + !node_set.is_empty() + } + }); + if irrefutable { + let lvalue = match_pair.lvalue.downcast(adt_def, variant_index); + candidate.match_pairs.extend(self.field_match_pairs(lvalue, subpatterns)); + Ok(()) + } else { + Err(match_pair) } - }); - if irrefutable { - let lvalue = match_pair.lvalue.downcast(adt_def, variant_index); - candidate.match_pairs.extend(self.field_match_pairs(lvalue, subpatterns)); - Ok(()) } else { Err(match_pair) } diff --git a/src/test/compile-fail/uninhabited-matches-feature-gated.rs b/src/test/compile-fail/uninhabited-matches-feature-gated.rs new file mode 100644 index 0000000000000..0f8b0a6c238d0 --- /dev/null +++ b/src/test/compile-fail/uninhabited-matches-feature-gated.rs @@ -0,0 +1,50 @@ +// Copyright 2016 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 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![feature(slice_patterns)] + +enum Void {} + +fn main() { + let x: Result = Ok(23); + let _ = match x { //~ ERROR non-exhaustive + Ok(n) => n, + }; + + let x: &Void = unsafe { std::mem::uninitialized() }; + let _ = match x {}; + //~^ ERROR non-exhaustive + + let x: (Void,) = unsafe { std::mem::uninitialized() }; + let _ = match x {}; + //~^ ERROR non-exhaustive + + let x: [Void; 1] = unsafe { std::mem::uninitialized() }; + let _ = match x {}; + //~^ ERROR non-exhaustive + + let x: &[Void] = unsafe { std::mem::uninitialized() }; + let _ = match x { //~ ERROR non-exhaustive + &[] => (), + }; + + let x: Void = unsafe { std::mem::uninitialized() }; + let _ = match x {}; // okay + + let x: Result = Ok(23); + let _ = match x { //~ ERROR non-exhaustive + Ok(x) => x, + }; + + let x: Result = Ok(23); + let Ok(x) = x; + //~^ ERROR refutable +} + diff --git a/src/test/compile-fail/uninhabited-reference-type-feature-gated.rs b/src/test/compile-fail/uninhabited-reference-type-feature-gated.rs deleted file mode 100644 index 8f246eddbcde4..0000000000000 --- a/src/test/compile-fail/uninhabited-reference-type-feature-gated.rs +++ /dev/null @@ -1,19 +0,0 @@ -// Copyright 2016 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 or the MIT license -// , at your -// option. This file may not be copied, modified, or distributed -// except according to those terms. - -enum Void {} - -fn main() { - let x: Result = Ok(23); - let _ = match x { //~ ERROR non-exhaustive - Ok(n) => n, - }; -} -