Check in CI that the crate builds on targets without libstd

.travis.yml

@@ -33,8 +33,8 @@ matrix:
     - name: "x86_64-unknown-linux-gnu (stable)"
       rust: stable
       env: TARGET=x86_64-unknown-linux-gnu
-    - name: "x86_64-unknown-linux-gnu (Rust 1.31.0)"
-      rust: 1.31.0
+    - name: "x86_64-unknown-linux-gnu (Rust 1.32.0)"
+      rust: 1.32.0
       env: TARGET=x86_64-unknown-linux-gnu
     - name: "i686-unknown-linux-gnu"
       env: TARGET=i686-unknown-linux-gnu CROSS=1
@@ -62,6 +62,14 @@ matrix:
     - name: "aarch64-unknown-linux-gnu"
       env: TARGET=aarch64-unknown-linux-gnu CROSS=1
 
+    # Ensure that we successfully build without libstd
+    - name: "thumbv6m-none-eabi"
+      env: TARGET=thumbv6m-none-eabi NO_STD=1
+      script:
+        # cross doesn't seem to work with thumb targets...
+        - rustup target install $TARGET
+        - sh ci/run.sh
+
 install: travis_retry rustup target add "${TARGET}"
 script: sh ci/run.sh
 

Cargo.toml

@@ -14,7 +14,7 @@ build = "build.rs"
 
 [dependencies]
 # For the default hasher
-ahash = { version = "0.2", optional = true }
+ahash = { version = "0.2.11", optional = true }
 
 # For external trait impls
 rayon = { version = "1.0", optional = true }

ci/run.sh

@@ -4,7 +4,14 @@ set -ex
 
 : "${TARGET?The TARGET environment variable must be set.}"
 
-FEATURES="rayon,serde,rustc-internal-api"
+if [ "${NO_STD}" = "1" ]; then
+    # Unfortunately serde currently doesn't work without std due to a cargo bug.
+    FEATURES="rustc-internal-api"
+    OP="build"
+else
+    FEATURES="rustc-internal-api,serde,rayon"
+    OP="test"
+fi
 if [ "${TRAVIS_RUST_VERSION}" = "nightly" ]; then
     FEATURES="${FEATURES},nightly"
     export RUSTFLAGS="$RUSTFLAGS -D warnings"
@@ -19,18 +26,17 @@ if [ "${CROSS}" = "1" ]; then
     CARGO=cross
 fi
 
-export RUSTFLAGS="$RUSTFLAGS --cfg hashbrown_deny_warnings"
-
 # Make sure we can compile without the default hasher
-"${CARGO}" -vv check --target="${TARGET}" --no-default-features
+"${CARGO}" -vv build --target="${TARGET}" --no-default-features
+"${CARGO}" -vv build --target="${TARGET}" --release --no-default-features
 
-"${CARGO}" -vv test --target="${TARGET}"
-"${CARGO}" -vv test --target="${TARGET}" --features "${FEATURES}"
+"${CARGO}" -vv ${OP} --target="${TARGET}"
+"${CARGO}" -vv ${OP} --target="${TARGET}" --features "${FEATURES}"
 
-"${CARGO}" -vv test --target="${TARGET}" --release
-"${CARGO}" -vv test --target="${TARGET}" --release --features "${FEATURES}"
+"${CARGO}" -vv ${OP} --target="${TARGET}" --release
+"${CARGO}" -vv ${OP} --target="${TARGET}" --release --features "${FEATURES}"
 
-if [ "${TRAVIS_RUST_VERSION}" = "nightly" ]; then
+if [ "${TRAVIS_RUST_VERSION}" = "nightly" ] && [ "${NO_STD}" != 1 ]; then
     # Run benchmark on native targets, build them on non-native ones:
     NO_RUN=""
     if [ "${CROSS}" = "1" ]; then

ci/tools.sh

@@ -13,7 +13,7 @@ retry() {
         "$@"
         result=$?
         [ $result -eq 0 ] && break
-        count=$(count + 1)
+        count=$((count + 1))
         sleep 1
     done
 

src/map.rs

@@ -18,7 +18,7 @@ pub enum DefaultHashBuilder {}
 
 /// A hash map implemented with quadratic probing and SIMD lookup.
 ///
-/// The default hashing algorithm is currently [AHash], though this is
+/// The default hashing algorithm is currently [`AHash`], though this is
 /// subject to change at any point in the future. This hash function is very
 /// fast for all types of keys, but this algorithm will typically *not* protect
 /// against attacks such as HashDoS.
@@ -145,7 +145,7 @@ pub enum DefaultHashBuilder {}
 /// [`with_hasher`]: #method.with_hasher
 /// [`with_capacity_and_hasher`]: #method.with_capacity_and_hasher
 /// [`fnv`]: https://crates.io/crates/fnv
-/// [AHash]: https://crates.io/crates/ahash
+/// [`AHash`]: https://crates.io/crates/ahash
 ///
 /// ```
 /// use hashbrown::HashMap;

src/raw/mod.rs

@@ -73,18 +73,20 @@ impl Fallibility {
     /// Error to return on capacity overflow.
     #[inline]
     fn capacity_overflow(self) -> CollectionAllocErr {
+        use Fallibility::*;
         match self {
-            Fallibility::Fallible => CollectionAllocErr::CapacityOverflow,
-            Fallibility::Infallible => panic!("Hash table capacity overflow"),
+            Fallible => CollectionAllocErr::CapacityOverflow,
+            Infallible => panic!("Hash table capacity overflow"),
         }
     }
 
     /// Error to return on allocation error.
     #[inline]
     fn alloc_err(self, layout: Layout) -> CollectionAllocErr {
+        use Fallibility::*;
         match self {
-            Fallibility::Fallible => CollectionAllocErr::AllocErr { layout },
-            Fallibility::Infallible => handle_alloc_error(layout),
+            Fallible => CollectionAllocErr::AllocErr { layout },
+            Infallible => handle_alloc_error(layout),
         }
     }
 }