From 1246d4067fdc034d064dfb78f88c2c3c079c3f4f Mon Sep 17 00:00:00 2001 From: James Miller Date: Fri, 9 Jan 2015 16:10:57 +1300 Subject: [PATCH] Add `core::num::wrapping` and fix overflow errors. Many of the core rust libraries have places that rely on integer wrapping behaviour. These places have been altered to use the wrapping_* methods: * core::hash::sip - A number of macros * core::str - The `maximal_suffix` method in `TwoWaySearcher` * rustc::util::nodemap - Implementation of FnvHash * rustc_back::sha2 - A number of macros and other places * rand::isaac - Isaac64Rng, changed to use the Wrapping helper type Some places had "benign" underflow. This is when underflow or overflow occurs, but the unspecified value is not used due to other conditions. * collections::bit::Bitv - underflow when `self.nbits` is zero. * collections::hash::{map,table} - Underflow when searching an empty table. Did cause undefined behaviour in this case due to an out-of-bounds ptr::offset based on the underflowed index. However the resulting pointers would never be read from. * syntax::ext::deriving::encodable - Underflow when calculating the index of the last field in a variant with no fields. These cases were altered to avoid the underflow, often by moving the underflowing operation to a place where underflow could not happen. There was one case that relied on the fact that unsigned arithmetic and two's complement arithmetic are identical with wrapping semantics. This was changed to use the wrapping_* methods. Finally, the calculation of variant discriminants could overflow if the preceeding discriminant was `U64_MAX`. The logic in `rustc::middle::ty` for this was altered to avoid the overflow completely, while the remaining places were changed to use wrapping methods. This is because `rustc::middle::ty::enum_variants` now throws an error when the calculated discriminant value overflows a `u64`. This behaviour can be triggered by the following code: ``` enum Foo { A = U64_MAX, B } ``` This commit also implements the remaining integer operators for Wrapped. --- src/libcollections/bit.rs | 6 +- src/libcore/hash/sip.rs | 12 +- src/libcore/num/mod.rs | 3 + src/libcore/num/wrapping.rs | 153 ++++++++++++++++++++++++ src/libcore/str/mod.rs | 9 +- src/librand/distributions/range.rs | 3 +- src/librand/isaac.rs | 74 ++++++------ src/librustc/metadata/decoder.rs | 2 +- src/librustc/metadata/encoder.rs | 2 +- src/librustc/middle/astencode.rs | 4 +- src/librustc/middle/ty.rs | 21 +++- src/librustc/util/nodemap.rs | 2 +- src/librustc_back/sha2.rs | 28 +++-- src/librustc_typeck/check/mod.rs | 9 +- src/libstd/collections/hash/map.rs | 7 ++ src/libstd/collections/hash/table.rs | 6 +- src/libstd/num/mod.rs | 1 + src/libstd/prelude/v1.rs | 2 + src/libsyntax/ext/deriving/encodable.rs | 37 +++--- 19 files changed, 286 insertions(+), 95 deletions(-) create mode 100644 src/libcore/num/wrapping.rs diff --git a/src/libcollections/bit.rs b/src/libcollections/bit.rs index a92eccce142..05bf5f8e42c 100644 --- a/src/libcollections/bit.rs +++ b/src/libcollections/bit.rs @@ -818,11 +818,11 @@ impl BitVec { let full_value = if value { !0 } else { 0 }; // Correct the old tail word, setting or clearing formerly unused bits - let old_last_word = blocks_for_bits(self.nbits) - 1; + let num_cur_blocks = blocks_for_bits(self.nbits); if self.nbits % u32::BITS as usize > 0 { let mask = mask_for_bits(self.nbits); if value { - self.storage[old_last_word] |= !mask; + self.storage[num_cur_blocks - 1] |= !mask; } else { // Extra bits are already zero by invariant. } @@ -830,7 +830,7 @@ impl BitVec { // Fill in words after the old tail word let stop_idx = cmp::min(self.storage.len(), new_nblocks); - for idx in old_last_word + 1..stop_idx { + for idx in num_cur_blocks..stop_idx { self.storage[idx] = full_value; } diff --git a/src/libcore/hash/sip.rs b/src/libcore/hash/sip.rs index 39bcbacdff1..df0008c500b 100644 --- a/src/libcore/hash/sip.rs +++ b/src/libcore/hash/sip.rs @@ -14,7 +14,7 @@ use prelude::*; use default::Default; - +use num::wrapping::WrappingOps; use super::Hasher; /// An implementation of SipHash 2-4. @@ -71,17 +71,17 @@ macro_rules! u8to64_le { macro_rules! rotl { ($x:expr, $b:expr) => - (($x << $b) | ($x >> (64 - $b))) + (($x << $b) | ($x >> (64.wrapping_sub($b)))) } macro_rules! compress { ($v0:expr, $v1:expr, $v2:expr, $v3:expr) => ({ - $v0 += $v1; $v1 = rotl!($v1, 13); $v1 ^= $v0; + $v0 = $v0.wrapping_add($v1); $v1 = rotl!($v1, 13); $v1 ^= $v0; $v0 = rotl!($v0, 32); - $v2 += $v3; $v3 = rotl!($v3, 16); $v3 ^= $v2; - $v0 += $v3; $v3 = rotl!($v3, 21); $v3 ^= $v0; - $v2 += $v1; $v1 = rotl!($v1, 17); $v1 ^= $v2; + $v2 = $v2.wrapping_add($v3); $v3 = rotl!($v3, 16); $v3 ^= $v2; + $v0 = $v0.wrapping_add($v3); $v3 = rotl!($v3, 21); $v3 ^= $v0; + $v2 = $v2.wrapping_add($v1); $v1 = rotl!($v1, 17); $v1 ^= $v2; $v2 = rotl!($v2, 32); }) } diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs index d77a1eb4203..3ed059520b1 100644 --- a/src/libcore/num/mod.rs +++ b/src/libcore/num/mod.rs @@ -30,6 +30,9 @@ use option::Option::{self, Some, None}; use result::Result::{self, Ok, Err}; use str::{FromStr, StrExt}; +#[unstable(feature = "core", reason = "may be removed or relocated")] +pub mod wrapping; + /// A built-in signed or unsigned integer. #[stable(feature = "rust1", since = "1.0.0")] pub trait Int diff --git a/src/libcore/num/wrapping.rs b/src/libcore/num/wrapping.rs new file mode 100644 index 00000000000..30478a8f09f --- /dev/null +++ b/src/libcore/num/wrapping.rs @@ -0,0 +1,153 @@ +// Copyright 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 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. +#![allow(missing_docs)] + +use ops::*; + +#[cfg(not(stage0))] +use intrinsics::{overflowing_add, overflowing_sub, overflowing_mul}; + +pub trait WrappingOps { + fn wrapping_add(self, rhs: Self) -> Self; + fn wrapping_sub(self, rhs: Self) -> Self; + fn wrapping_mul(self, rhs: Self) -> Self; +} + +#[cfg(not(stage0))] +macro_rules! wrapping_impl { + ($($t:ty)*) => ($( + impl WrappingOps for $t { + #[inline(always)] + fn wrapping_add(self, rhs: $t) -> $t { + unsafe { + overflowing_add(self, rhs) + } + } + #[inline(always)] + fn wrapping_sub(self, rhs: $t) -> $t { + unsafe { + overflowing_sub(self, rhs) + } + } + #[inline(always)] + fn wrapping_mul(self, rhs: $t) -> $t { + unsafe { + overflowing_mul(self, rhs) + } + } + } + )*) +} + +#[cfg(stage0)] +macro_rules! wrapping_impl { + ($($t:ty)*) => ($( + impl WrappingOps for $t { + #[inline(always)] + fn wrapping_add(self, rhs: $t) -> $t { + self + rhs + } + #[inline(always)] + fn wrapping_sub(self, rhs: $t) -> $t { + self - rhs + } + #[inline(always)] + fn wrapping_mul(self, rhs: $t) -> $t { + self * rhs + } + } + )*) +} + +wrapping_impl! { uint u8 u16 u32 u64 int i8 i16 i32 i64 } + +#[unstable(feature = "core", reason = "may be removed, renamed, or relocated")] +#[derive(PartialEq,Eq,PartialOrd,Ord,Clone,Copy)] +pub struct Wrapping(pub T); + +impl Add for Wrapping { + type Output = Wrapping; + + #[inline(always)] + fn add(self, other: Wrapping) -> Wrapping { + Wrapping(self.0.wrapping_add(other.0)) + } +} + +impl Sub for Wrapping { + type Output = Wrapping; + + #[inline(always)] + fn sub(self, other: Wrapping) -> Wrapping { + Wrapping(self.0.wrapping_sub(other.0)) + } +} + +impl Mul for Wrapping { + type Output = Wrapping; + + #[inline(always)] + fn mul(self, other: Wrapping) -> Wrapping { + Wrapping(self.0.wrapping_mul(other.0)) + } +} + +impl> Not for Wrapping { + type Output = Wrapping; + + fn not(self) -> Wrapping { + Wrapping(!self.0) + } +} + +impl> BitXor for Wrapping { + type Output = Wrapping; + + #[inline(always)] + fn bitxor(self, other: Wrapping) -> Wrapping { + Wrapping(self.0 ^ other.0) + } +} + +impl> BitOr for Wrapping { + type Output = Wrapping; + + #[inline(always)] + fn bitor(self, other: Wrapping) -> Wrapping { + Wrapping(self.0 | other.0) + } +} + +impl> BitAnd for Wrapping { + type Output = Wrapping; + + #[inline(always)] + fn bitand(self, other: Wrapping) -> Wrapping { + Wrapping(self.0 & other.0) + } +} + +impl> Shl for Wrapping { + type Output = Wrapping; + + #[inline(always)] + fn shl(self, other: uint) -> Wrapping { + Wrapping(self.0 << other) + } +} + +impl> Shr for Wrapping { + type Output = Wrapping; + + #[inline(always)] + fn shr(self, other: uint) -> Wrapping { + Wrapping(self.0 >> other) + } +} diff --git a/src/libcore/str/mod.rs b/src/libcore/str/mod.rs index b354116993c..a7a06906409 100644 --- a/src/libcore/str/mod.rs +++ b/src/libcore/str/mod.rs @@ -830,6 +830,7 @@ impl TwoWaySearcher { #[inline] #[allow(dead_code)] fn maximal_suffix(arr: &[u8], reversed: bool) -> (usize, usize) { + use num::wrapping::WrappingOps; let mut left = -1; // Corresponds to i in the paper let mut right = 0; // Corresponds to j in the paper let mut offset = 1; // Corresponds to k in the paper @@ -839,17 +840,17 @@ impl TwoWaySearcher { let a; let b; if reversed { - a = arr[left + offset]; + a = arr[left.wrapping_add(offset)]; b = arr[right + offset]; } else { a = arr[right + offset]; - b = arr[left + offset]; + b = arr[left.wrapping_add(offset)]; } if a < b { // Suffix is smaller, period is entire prefix so far. right += offset; offset = 1; - period = right - left; + period = right.wrapping_sub(left); } else if a == b { // Advance through repetition of the current period. if offset == period { @@ -866,7 +867,7 @@ impl TwoWaySearcher { period = 1; } } - (left + 1, period) + (left.wrapping_add(1), period) } } diff --git a/src/librand/distributions/range.rs b/src/librand/distributions/range.rs index 6eb1d68a081..04c67b16a7c 100644 --- a/src/librand/distributions/range.rs +++ b/src/librand/distributions/range.rs @@ -14,6 +14,7 @@ use core::prelude::{PartialOrd}; use core::num::Int; +use core::num::wrapping::WrappingOps; use Rng; use distributions::{Sample, IndependentSample}; @@ -97,7 +98,7 @@ macro_rules! integer_impl { // bijection. fn construct_range(low: $ty, high: $ty) -> Range<$ty> { - let range = high as $unsigned - low as $unsigned; + let range = (high as $unsigned).wrapping_sub(low as $unsigned); let unsigned_max: $unsigned = Int::max_value(); // this is the largest number that fits into $unsigned diff --git a/src/librand/isaac.rs b/src/librand/isaac.rs index 701749ff344..63eb8417655 100644 --- a/src/librand/isaac.rs +++ b/src/librand/isaac.rs @@ -304,7 +304,7 @@ impl Isaac64Rng { fn init(&mut self, use_rsl: bool) { macro_rules! init { ($var:ident) => ( - let mut $var = 0x9e3779b97f4a7c13; + let mut $var = Wrapping(0x9e3779b97f4a7c13); ) } init!(a); init!(b); init!(c); init!(d); @@ -312,14 +312,14 @@ impl Isaac64Rng { macro_rules! mix { () => {{ - a-=e; f^=h>>9; h+=a; - b-=f; g^=a<<9; a+=b; - c-=g; h^=b>>23; b+=c; - d-=h; a^=c<<15; c+=d; - e-=a; b^=d>>14; d+=e; - f-=b; c^=e<<20; e+=f; - g-=c; d^=f>>17; f+=g; - h-=d; e^=g<<14; g+=h; + a=a-e; f=f^h>>9; h=h+a; + b=b-f; g=g^a<<9; a=a+b; + c=c-g; h=h^b>>23; b=b+c; + d=d-h; a=a^c<<15; c=c+d; + e=e-a; b=b^d>>14; d=d+e; + f=f-b; c=c^e<<20; e=e+f; + g=g-c; d=d^f>>17; f=f+g; + h=h-d; e=e^g<<14; g=g+h; }} } @@ -331,15 +331,15 @@ impl Isaac64Rng { macro_rules! memloop { ($arr:expr) => {{ for i in (0..RAND_SIZE_64 / 8).map(|i| i * 8) { - a+=$arr[i ]; b+=$arr[i+1]; - c+=$arr[i+2]; d+=$arr[i+3]; - e+=$arr[i+4]; f+=$arr[i+5]; - g+=$arr[i+6]; h+=$arr[i+7]; + a=a+Wrapping($arr[i ]); b=b+Wrapping($arr[i+1]); + c=c+Wrapping($arr[i+2]); d=d+Wrapping($arr[i+3]); + e=e+Wrapping($arr[i+4]); f=f+Wrapping($arr[i+5]); + g=g+Wrapping($arr[i+6]); h=h+Wrapping($arr[i+7]); mix!(); - self.mem[i ]=a; self.mem[i+1]=b; - self.mem[i+2]=c; self.mem[i+3]=d; - self.mem[i+4]=e; self.mem[i+5]=f; - self.mem[i+6]=g; self.mem[i+7]=h; + self.mem[i ]=a.0; self.mem[i+1]=b.0; + self.mem[i+2]=c.0; self.mem[i+3]=d.0; + self.mem[i+4]=e.0; self.mem[i+5]=f.0; + self.mem[i+6]=g.0; self.mem[i+7]=h.0; } }} } @@ -349,10 +349,10 @@ impl Isaac64Rng { } else { for i in (0..RAND_SIZE_64 / 8).map(|i| i * 8) { mix!(); - self.mem[i ]=a; self.mem[i+1]=b; - self.mem[i+2]=c; self.mem[i+3]=d; - self.mem[i+4]=e; self.mem[i+5]=f; - self.mem[i+6]=g; self.mem[i+7]=h; + self.mem[i ]=a.0; self.mem[i+1]=b.0; + self.mem[i+2]=c.0; self.mem[i+3]=d.0; + self.mem[i+4]=e.0; self.mem[i+5]=f.0; + self.mem[i+6]=g.0; self.mem[i+7]=h.0; } } @@ -363,8 +363,8 @@ impl Isaac64Rng { fn isaac64(&mut self) { self.c += 1; // abbreviations - let mut a = self.a; - let mut b = self.b + self.c; + let mut a = Wrapping(self.a); + let mut b = Wrapping(self.b) + Wrapping(self.c); const MIDPOINT: uint = RAND_SIZE_64 / 2; const MP_VEC: [(uint, uint); 2] = [(0,MIDPOINT), (MIDPOINT, 0)]; macro_rules! ind { @@ -383,13 +383,13 @@ impl Isaac64Rng { let mix = if $j == 0 {!mix} else {mix}; unsafe { - let x = *self.mem.get_unchecked(base + mr_offset); - a = mix + *self.mem.get_unchecked(base + m2_offset); - let y = ind!(x) + a + b; - *self.mem.get_unchecked_mut(base + mr_offset) = y; + let x = Wrapping(*self.mem.get_unchecked(base + mr_offset)); + a = mix + Wrapping(*self.mem.get_unchecked(base + m2_offset)); + let y = Wrapping(ind!(x.0)) + a + b; + *self.mem.get_unchecked_mut(base + mr_offset) = y.0; - b = ind!(y >> RAND_SIZE_64_LEN) + x; - *self.rsl.get_unchecked_mut(base + mr_offset) = b; + b = Wrapping(ind!(y.0 >> RAND_SIZE_64_LEN)) + x; + *self.rsl.get_unchecked_mut(base + mr_offset) = b.0; } }} } @@ -401,13 +401,13 @@ impl Isaac64Rng { let mix = if $j == 0 {!mix} else {mix}; unsafe { - let x = *self.mem.get_unchecked(base + mr_offset); - a = mix + *self.mem.get_unchecked(base + m2_offset); - let y = ind!(x) + a + b; - *self.mem.get_unchecked_mut(base + mr_offset) = y; + let x = Wrapping(*self.mem.get_unchecked(base + mr_offset)); + a = mix + Wrapping(*self.mem.get_unchecked(base + m2_offset)); + let y = Wrapping(ind!(x.0)) + a + b; + *self.mem.get_unchecked_mut(base + mr_offset) = y.0; - b = ind!(y >> RAND_SIZE_64_LEN) + x; - *self.rsl.get_unchecked_mut(base + mr_offset) = b; + b = Wrapping(ind!(y.0 >> RAND_SIZE_64_LEN)) + x; + *self.rsl.get_unchecked_mut(base + mr_offset) = b.0; } }} } @@ -419,8 +419,8 @@ impl Isaac64Rng { } } - self.a = a; - self.b = b; + self.a = a.0; + self.b = b.0; self.cnt = RAND_SIZE_64; } } diff --git a/src/librustc/metadata/decoder.rs b/src/librustc/metadata/decoder.rs index 251c5e6eac7..e32fcaec047 100644 --- a/src/librustc/metadata/decoder.rs +++ b/src/librustc/metadata/decoder.rs @@ -783,7 +783,7 @@ pub fn get_enum_variants<'tcx>(intr: Rc, cdata: Cmd, id: ast::Nod _ => { /* empty */ } } let old_disr_val = disr_val; - disr_val += 1; + disr_val = disr_val.wrapping_add(1); Rc::new(ty::VariantInfo { args: arg_tys, arg_names: arg_names, diff --git a/src/librustc/metadata/encoder.rs b/src/librustc/metadata/encoder.rs index 131a299cc50..8152a2bf16d 100644 --- a/src/librustc/metadata/encoder.rs +++ b/src/librustc/metadata/encoder.rs @@ -347,7 +347,7 @@ fn encode_enum_variant_info(ecx: &EncodeContext, ecx.tcx.map.with_path(variant.node.id, |path| encode_path(rbml_w, path)); rbml_w.end_tag(); - disr_val += 1; + disr_val = disr_val.wrapping_add(1); i += 1; } } diff --git a/src/librustc/middle/astencode.rs b/src/librustc/middle/astencode.rs index 599dde4b701..33c0fb8b031 100644 --- a/src/librustc/middle/astencode.rs +++ b/src/librustc/middle/astencode.rs @@ -204,7 +204,9 @@ impl<'a, 'b, 'tcx> DecodeContext<'a, 'b, 'tcx> { pub fn tr_id(&self, id: ast::NodeId) -> ast::NodeId { // from_id_range should be non-empty assert!(!self.from_id_range.empty()); - (id - self.from_id_range.min + self.to_id_range.min) + // Use wrapping arithmetic because otherwise it introduces control flow. + // Maybe we should just have the control flow? -- aatch + (id.wrapping_sub(self.from_id_range.min).wrapping_add(self.to_id_range.min)) } /// Translates an EXTERNAL def-id, converting the crate number from the one used in the encoded diff --git a/src/librustc/middle/ty.rs b/src/librustc/middle/ty.rs index aaba840825e..b6d1fc5a369 100644 --- a/src/librustc/middle/ty.rs +++ b/src/librustc/middle/ty.rs @@ -5333,6 +5333,7 @@ pub fn type_is_empty(cx: &ctxt, ty: Ty) -> bool { pub fn enum_variants<'tcx>(cx: &ctxt<'tcx>, id: ast::DefId) -> Rc>>> { + use std::num::Int; // For checked_add memoized(&cx.enum_var_cache, id, |id: ast::DefId| { if ast::LOCAL_CRATE != id.krate { Rc::new(csearch::get_enum_variants(cx, id)) @@ -5349,11 +5350,7 @@ pub fn enum_variants<'tcx>(cx: &ctxt<'tcx>, id: ast::DefId) let mut last_discriminant: Option = None; Rc::new(enum_definition.variants.iter().map(|variant| { - let mut discriminant = match last_discriminant { - Some(val) => val + 1, - None => INITIAL_DISCRIMINANT_VALUE - }; - + let mut discriminant = INITIAL_DISCRIMINANT_VALUE; if let Some(ref e) = variant.node.disr_expr { // Preserve all values, and prefer signed. let ty = Some(cx.types.i64); @@ -5373,7 +5370,19 @@ pub fn enum_variants<'tcx>(cx: &ctxt<'tcx>, id: ast::DefId) "expected constant: {}", err); } } - }; + } else { + if let Some(val) = last_discriminant { + if let Some(v) = val.checked_add(1) { + discriminant = v + } else { + cx.sess.span_err( + variant.span, + &format!("Discriminant overflowed!")); + } + } else { + discriminant = INITIAL_DISCRIMINANT_VALUE; + } + } last_discriminant = Some(discriminant); Rc::new(VariantInfo::from_ast_variant(cx, &**variant, diff --git a/src/librustc/util/nodemap.rs b/src/librustc/util/nodemap.rs index b15da7dab3e..0f69aa941a3 100644 --- a/src/librustc/util/nodemap.rs +++ b/src/librustc/util/nodemap.rs @@ -57,7 +57,7 @@ impl Hasher for FnvHasher { let FnvHasher(mut hash) = *self; for byte in bytes { hash = hash ^ (*byte as u64); - hash = hash * 0x100000001b3; + hash = hash.wrapping_mul(0x100000001b3); } *self = FnvHasher(hash); } diff --git a/src/librustc_back/sha2.rs b/src/librustc_back/sha2.rs index 6654a46f7c3..8acb6851f11 100644 --- a/src/librustc_back/sha2.rs +++ b/src/librustc_back/sha2.rs @@ -347,17 +347,19 @@ impl Engine256State { // Sha-512 and Sha-256 use basically the same calculations which are implemented // by these macros. Inlining the calculations seems to result in better generated code. macro_rules! schedule_round { ($t:expr) => ( - w[$t] = sigma1(w[$t - 2]) + w[$t - 7] + sigma0(w[$t - 15]) + w[$t - 16]; - ) + w[$t] = sigma1(w[$t - 2]).wrapping_add(w[$t - 7]) + .wrapping_add(sigma0(w[$t - 15])).wrapping_add(w[$t - 16]); + ) } macro_rules! sha2_round { ($A:ident, $B:ident, $C:ident, $D:ident, $E:ident, $F:ident, $G:ident, $H:ident, $K:ident, $t:expr) => ( { - $H += sum1($E) + ch($E, $F, $G) + $K[$t] + w[$t]; - $D += $H; - $H += sum0($A) + maj($A, $B, $C); + $H = $H.wrapping_add(sum1($E)).wrapping_add(ch($E, $F, $G)) + .wrapping_add($K[$t]).wrapping_add(w[$t]); + $D = $D.wrapping_add($H); + $H = $H.wrapping_add(sum0($A)).wrapping_add(maj($A, $B, $C)); } ) } @@ -397,14 +399,14 @@ impl Engine256State { sha2_round!(b, c, d, e, f, g, h, a, K32, t + 7); } - self.h0 += a; - self.h1 += b; - self.h2 += c; - self.h3 += d; - self.h4 += e; - self.h5 += f; - self.h6 += g; - self.h7 += h; + self.h0 = self.h0.wrapping_add(a); + self.h1 = self.h1.wrapping_add(b); + self.h2 = self.h2.wrapping_add(c); + self.h3 = self.h3.wrapping_add(d); + self.h4 = self.h4.wrapping_add(e); + self.h5 = self.h5.wrapping_add(f); + self.h6 = self.h6.wrapping_add(g); + self.h7 = self.h7.wrapping_add(h); } } diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs index 273aadc383c..10771935e22 100644 --- a/src/librustc_typeck/check/mod.rs +++ b/src/librustc_typeck/check/mod.rs @@ -4554,6 +4554,7 @@ pub fn check_enum_variants<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>, id: ast::NodeId, hint: attr::ReprAttr) -> Vec>> { + use std::num::Int; let rty = ty::node_id_to_type(ccx.tcx, id); let mut variants: Vec> = Vec::new(); @@ -4565,7 +4566,13 @@ pub fn check_enum_variants<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>, // If the discriminant value is specified explicitly in the enum check whether the // initialization expression is valid, otherwise use the last value plus one. let mut current_disr_val = match prev_disr_val { - Some(prev_disr_val) => prev_disr_val + 1, + Some(prev_disr_val) => { + if let Some(v) = prev_disr_val.checked_add(1) { + v + } else { + ty::INITIAL_DISCRIMINANT_VALUE + } + } None => ty::INITIAL_DISCRIMINANT_VALUE }; diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs index faddbba5059..8eb29a8327a 100644 --- a/src/libstd/collections/hash/map.rs +++ b/src/libstd/collections/hash/map.rs @@ -314,6 +314,13 @@ fn search_hashed(table: M, M: Deref>, F: FnMut(&K) -> bool, { + // This is the only function where capacity can be zero. To avoid + // undefined behaviour when Bucket::new gets the raw bucket in this + // case, immediately return the appropriate search result. + if table.capacity() == 0 { + return TableRef(table); + } + let size = table.size(); let mut probe = Bucket::new(table, hash); let ib = probe.index(); diff --git a/src/libstd/collections/hash/table.rs b/src/libstd/collections/hash/table.rs index 4c03d8915eb..908b5267b69 100644 --- a/src/libstd/collections/hash/table.rs +++ b/src/libstd/collections/hash/table.rs @@ -224,6 +224,9 @@ impl>> Bucket { } pub fn at_index(table: M, ib_index: usize) -> Bucket { + // if capacity is 0, then the RawBucket will be populated with bogus pointers. + // This is an uncommon case though, so avoid it in release builds. + debug_assert!(table.capacity() > 0, "Table should have capacity at this point"); let ib_index = ib_index & (table.capacity() - 1); Bucket { raw: unsafe { @@ -368,10 +371,11 @@ impl>> FullBucket { /// In the cited blog posts above, this is called the "distance to /// initial bucket", or DIB. Also known as "probe count". pub fn distance(&self) -> usize { + use core::num::wrapping::WrappingOps; // Calculates the distance one has to travel when going from // `hash mod capacity` onwards to `idx mod capacity`, wrapping around // if the destination is not reached before the end of the table. - (self.idx - self.hash().inspect() as usize) & (self.table.capacity() - 1) + (self.idx.wrapping_sub(self.hash().inspect() as usize)) & (self.table.capacity() - 1) } #[inline] diff --git a/src/libstd/num/mod.rs b/src/libstd/num/mod.rs index d776079efae..d4428282b14 100644 --- a/src/libstd/num/mod.rs +++ b/src/libstd/num/mod.rs @@ -30,6 +30,7 @@ pub use core::num::{from_uint, from_u8, from_u16, from_u32, from_u64}; pub use core::num::{from_f32, from_f64}; pub use core::num::{FromStrRadix, from_str_radix}; pub use core::num::{FpCategory, ParseIntError, ParseFloatError}; +pub use core::num::wrapping; use option::Option; diff --git a/src/libstd/prelude/v1.rs b/src/libstd/prelude/v1.rs index dad0ff0a15e..60e1354482c 100644 --- a/src/libstd/prelude/v1.rs +++ b/src/libstd/prelude/v1.rs @@ -58,3 +58,5 @@ #[doc(no_inline)] pub use old_io::{Buffer, Writer, Reader, Seek, BufferPrelude}; // NB: remove when range syntax lands #[doc(no_inline)] pub use iter::range; + +#[doc(no_inline)] pub use num::wrapping::{Wrapping, WrappingOps}; diff --git a/src/libsyntax/ext/deriving/encodable.rs b/src/libsyntax/ext/deriving/encodable.rs index 8038074cee1..94b7d1b4d8c 100644 --- a/src/libsyntax/ext/deriving/encodable.rs +++ b/src/libsyntax/ext/deriving/encodable.rs @@ -240,25 +240,24 @@ fn encodable_substructure(cx: &mut ExtCtxt, trait_span: Span, let encoder = cx.expr_ident(trait_span, blkarg); let emit_variant_arg = cx.ident_of("emit_enum_variant_arg"); let mut stmts = Vec::new(); - let last = fields.len() - 1; - for (i, &FieldInfo { ref self_, span, .. }) in fields.iter().enumerate() { - let enc = cx.expr_method_call(span, self_.clone(), - encode, vec!(blkencoder.clone())); - let lambda = cx.lambda_expr_1(span, enc, blkarg); - let call = cx.expr_method_call(span, blkencoder.clone(), - emit_variant_arg, - vec!(cx.expr_usize(span, i), - lambda)); - let call = if i != last { - cx.expr_try(span, call) - } else { - cx.expr(span, ExprRet(Some(call))) - }; - stmts.push(cx.stmt_expr(call)); - } - - // enums with no fields need to return Ok() - if stmts.len() == 0 { + if fields.len() > 0 { + let last = fields.len() - 1; + for (i, &FieldInfo { ref self_, span, .. }) in fields.iter().enumerate() { + let enc = cx.expr_method_call(span, self_.clone(), + encode, vec!(blkencoder.clone())); + let lambda = cx.lambda_expr_1(span, enc, blkarg); + let call = cx.expr_method_call(span, blkencoder.clone(), + emit_variant_arg, + vec!(cx.expr_usize(span, i), + lambda)); + let call = if i != last { + cx.expr_try(span, call) + } else { + cx.expr(span, ExprRet(Some(call))) + }; + stmts.push(cx.stmt_expr(call)); + } + } else { let ret_ok = cx.expr(trait_span, ExprRet(Some(cx.expr_ok(trait_span, cx.expr_tuple(trait_span, vec![])))));