Auto merge of #511 - Amanieu:clone_from_index, r=Amanieu

Fix index calculation in panic guard of clone_from_impl

Previously, it was possible for an uninitialized element to be dropped if all of the following occurred:
- `clone_from` was called where `T: !Copy`.
- The `clone` implementation of `T` panicked.
- The first bucket of the source `HashMap` contained an entry.

Fixes #510

Author: bors

.github/workflows/rust.yml

@@ -43,8 +43,6 @@ jobs:
     - env:
         TARGET: ${{ matrix.target }}
         CHANNEL: ${{ matrix.channel }}
-        CROSS: ${{ matrix.target != 'x86_64-unknown-linux-gnu' && '1' || '0' }}
-        NO_STD: ${{ matrix.target == 'thumbv6m-none-eabi' && '1' || '0' }}
       run: sh ci/run.sh
     strategy:
       matrix:
@@ -56,9 +54,10 @@ jobs:
           armv7-unknown-linux-gnueabihf,
           aarch64-unknown-linux-gnu,
           thumbv6m-none-eabi,
-          x86_64-pc-windows-gnu,
+          # Disabled due to issues with cross-rs
+          #x86_64-pc-windows-gnu,
         ]
-        channel: [1.72.0, nightly]
+        channel: [1.74.0, nightly]
         include:
         - os: macos-latest
           target: x86_64-apple-darwin
@@ -68,10 +67,10 @@ jobs:
           channel: nightly
         - os: macos-latest
           target: x86_64-apple-darwin
-          channel: 1.72.0
+          channel: 1.74.0
         - os: windows-latest
           target: x86_64-pc-windows-msvc
-          channel: 1.72.0
+          channel: 1.74.0
         - os: ubuntu-latest
           target: x86_64-unknown-linux-gnu
           channel: beta

ci/run.sh

@@ -4,6 +4,30 @@ set -ex
 
 : "${TARGET?The TARGET environment variable must be set.}"
 
+case "${TARGET}" in
+    x86_64-unknown-linux-gnu|x86_64-apple-darwin|x86_64-pc-windows-msvc)
+        CROSS=0
+        NO_STD=0
+        ;;
+    thumbv6m-none-eabi)
+        CROSS=1
+        NO_STD=1
+        ;;
+    *)
+        CROSS=1
+        NO_STD=0
+        ;;
+esac
+
+CARGO=cargo
+if [ "${CROSS}" = "1" ]; then
+    export CARGO_NET_RETRY=5
+    export CARGO_NET_TIMEOUT=10
+
+    cargo install --locked cross
+    CARGO=cross
+fi
+
 if [ "${NO_STD}" = "1" ]; then
     # Unfortunately serde currently doesn't work without std due to a cargo bug.
     FEATURES="rustc-internal-api"
@@ -12,20 +36,12 @@ else
     FEATURES="rustc-internal-api,serde,rayon,raw"
     OP="test"
 fi
+
 if [ "${CHANNEL}" = "nightly" ]; then
     FEATURES="${FEATURES},nightly"
     export RUSTFLAGS="$RUSTFLAGS -D warnings"
 fi
 
-CARGO=cargo
-if [ "${CROSS}" = "1" ]; then
-    export CARGO_NET_RETRY=5
-    export CARGO_NET_TIMEOUT=10
-
-    cargo install --locked cross
-    CARGO=cross
-fi
-
 # Make sure we can compile without the default hasher
 "${CARGO}" -vv build --target="${TARGET}" --no-default-features
 "${CARGO}" -vv build --target="${TARGET}" --release --no-default-features

src/map.rs

@@ -5,7 +5,7 @@ use crate::{Equivalent, TryReserveError};
 use core::borrow::Borrow;
 use core::fmt::{self, Debug};
 use core::hash::{BuildHasher, Hash};
-use core::iter::{FromIterator, FusedIterator};
+use core::iter::FusedIterator;
 use core::marker::PhantomData;
 use core::mem;
 use core::ops::Index;

src/raw/mod.rs

@@ -3582,7 +3582,7 @@ impl<T: Clone, A: Allocator + Clone> RawTable<T, A> {
         // cloned so far.
         let mut guard = guard((0, &mut *self), |(index, self_)| {
             if T::NEEDS_DROP {
-                for i in 0..=*index {
+                for i in 0..*index {
                     if self_.is_bucket_full(i) {
                         self_.bucket(i).drop();
                     }
@@ -3596,7 +3596,7 @@ impl<T: Clone, A: Allocator + Clone> RawTable<T, A> {
             to.write(from.as_ref().clone());
 
             // Update the index in case we need to unwind.
-            guard.0 = index;
+            guard.0 = index + 1;
         }
 
         // Successfully cloned all items, no need to clean up.

src/set.rs

@@ -4,7 +4,7 @@ use crate::{Equivalent, TryReserveError};
 use alloc::borrow::ToOwned;
 use core::fmt;
 use core::hash::{BuildHasher, Hash};
-use core::iter::{Chain, FromIterator, FusedIterator};
+use core::iter::{Chain, FusedIterator};
 use core::ops::{BitAnd, BitOr, BitXor, Sub};
 
 use super::map::{self, DefaultHashBuilder, HashMap, Keys};