Use autocfg to avoid breaking change

Author: leo60228

.travis.yml

@@ -2,7 +2,12 @@ language: rust
 sudo: false
 matrix:
   include:
-    - rust: 1.36.0
+    - rust: 1.18.0
+      before_script:
+        # lazy_static 1.1 requires Rust 1.21+, so downgrade it.
+        # (we only use it in benchmarks anyway...)
+        - cargo generate-lockfile
+        - cargo update -p lazy_static --precise 1.0.2
     - rust: stable
       env:
        - FEATURES='serde-1'
@@ -17,6 +22,6 @@ branches:
 script:
   - |
       cargo build --verbose --features "$FEATURES" &&
-      cargo test --verbose --features "$FEATURES" &&
-      cargo test --release --verbose --features "$FEATURES" &&
+      cargo test --verbose --features "$FEATURES",force_std &&
+      cargo test --release --verbose --features "$FEATURES",force_std &&
       cargo doc --verbose --features "$FEATURES"

Cargo.toml

@@ -25,6 +25,12 @@ indexmap.
 keywords = ["hashmap"]
 categories = ["data-structures"]
 
+[package.metadata.release]
+no-dev-version = true
+
+[package.metadata.docs.rs]
+features = ["serde-1"]
+
 [lib]
 bench = false
 
@@ -48,11 +54,34 @@ serde-1 = ["serde"]
 test_low_transition_point = []
 test_debug = []
 
+force_std = []
+
 [profile.bench]
 debug = true
 
-[package.metadata.release]
-no-dev-version = true
+[build-dependencies]
+autocfg = "0.1.5"
 
-[package.metadata.docs.rs]
-features = ["serde-1"]
+[[test]]
+name = "tests"
+required-features = [ "force_std" ]
+
+[[test]]
+name = "serde"
+required-features = [ "force_std" ]
+
+[[test]]
+name = "quick"
+required-features = [ "force_std" ]
+
+[[test]]
+name = "equivalent_trait"
+required-features = [ "force_std" ]
+
+[[bench]]
+name = "bench"
+required-features = [ "force_std" ]
+
+[[bench]]
+name = "faststring"
+required-features = [ "force_std" ]

README.rst

@@ -12,8 +12,8 @@ indexmap
 .. |docs| image:: https://docs.rs/indexmap/badge.svg
 .. _docs: https://docs.rs/indexmap
 
-.. |rustc| image:: https://img.shields.io/badge/rust-1.36%2B-orange.svg
-.. _rustc: https://img.shields.io/badge/rust-1.36%2B-orange.svg
+.. |rustc| image:: https://img.shields.io/badge/rust-1.18%2B-orange.svg
+.. _rustc: https://img.shields.io/badge/rust-1.18%2B-orange.svg
 
 A safe, pure-Rust hash table which preserves insertion order.
 

build.rs

@@ -0,0 +1,5 @@
+fn main() {
+    let ac = autocfg::new();
+    ac.emit_has_path("std");
+    ac.emit_has_path("alloc");
+}

src/lib.rs

@@ -14,19 +14,26 @@
 //!
 //! ## Rust Version
 //!
-//! This version of indexmap requires Rust 1.36 or later.
+//! This version of indexmap requires Rust 1.18 or later.
 //!
 //! The indexmap 1.x release series will use a carefully considered version
 //! upgrade policy, where in a later 1.x version, we will raise the minimum
 //! required Rust version.
 
-#![cfg_attr(not(test), no_std)]
+#![cfg_attr(all(not(test), has_alloc, not(feature = "force_std")), no_std)]
 
 #[cfg(test)]
 extern crate core;
 
+#[cfg(all(has_alloc, not(feature = "force_std")))]
 extern crate alloc;
 
+#[cfg(all(has_alloc, has_std))]
+extern crate std;
+
+#[cfg(any(not(has_alloc), feature = "force_std"))]
+extern crate std as alloc;
+
 #[macro_use]
 mod macros;
 #[cfg(feature = "serde-1")]

src/macros.rs

@@ -1,5 +1,5 @@
 #[macro_export]
-/// Create an `IndexMap` from a list of key-value pairs
+/// Create an `IndexMap` from a list of key-value pairs. Requires `std` to be available.
 ///
 /// ## Example
 ///
@@ -21,6 +21,7 @@
 /// assert_eq!(map.keys().next(), Some(&"a"));
 /// # }
 /// ```
+#[cfg(any(has_std, feature = "force_std", test))]
 macro_rules! indexmap {
     (@single $($x:tt)*) => (());
     (@count $($rest:expr),*) => (<[()]>::len(&[$(indexmap!(@single $rest)),*]));
@@ -60,6 +61,7 @@ macro_rules! indexmap {
 /// assert_eq!(set.iter().next(), Some(&"a"));
 /// # }
 /// ```
+#[cfg(any(has_std, feature = "force_std", test))]
 macro_rules! indexset {
     (@single $($x:tt)*) => (());
     (@count $($rest:expr),*) => (<[()]>::len(&[$(indexset!(@single $rest)),*]));

src/map.rs

@@ -7,7 +7,6 @@ use core::hash::Hash;
 use core::hash::BuildHasher;
 use core::hash::Hasher;
 use core::iter::FromIterator;
-use hashbrown::hash_map::DefaultHashBuilder;
 use core::ops::RangeFull;
 
 use core::cmp::{max, Ordering};
@@ -265,7 +264,15 @@ impl<Sz> ShortHashProxy<Sz>
 /// assert_eq!(letters.get(&'y'), None);
 /// ```
 #[derive(Clone)]
-pub struct IndexMap<K, V, S = DefaultHashBuilder> {
+#[cfg(any(has_std, feature = "force_std", test))]
+pub struct IndexMap<K, V, S = ::std::collections::hash_map::RandomState> {
+    core: OrderMapCore<K, V>,
+    hash_builder: S,
+}
+
+#[derive(Clone)]
+#[cfg(not(any(has_std, feature = "force_std", test)))]
+pub struct IndexMap<K, V, S> {
     core: OrderMapCore<K, V>,
     hash_builder: S,
 }
@@ -356,7 +363,8 @@ macro_rules! probe_loop {
     }
 }
 
-impl<K, V> IndexMap<K, V> {
+#[cfg(any(has_std, feature = "force_std", test))]
+impl<K, V> IndexMap<K, V, ::std::collections::hash_map::RandomState> {
     /// Create a new map. (Does not allocate.)
     pub fn new() -> Self {
         Self::with_capacity(0)

src/set.rs

@@ -1,7 +1,6 @@
 //! A hash set implemented using `IndexMap`
 
 use core::cmp::Ordering;
-use hashbrown::hash_map::DefaultHashBuilder;
 use core::fmt;
 use core::iter::{FromIterator, Chain};
 use core::hash::{Hash, BuildHasher};
@@ -57,7 +56,14 @@ type Bucket<T> = super::Bucket<T, ()>;
 /// assert!(!letters.contains(&'y'));
 /// ```
 #[derive(Clone)]
-pub struct IndexSet<T, S = DefaultHashBuilder> {
+#[cfg(any(has_std, feature = "force_std", test))]
+pub struct IndexSet<T, S = ::std::collections::hash_map::RandomState> {
+    map: IndexMap<T, (), S>,
+}
+
+#[derive(Clone)]
+#[cfg(not(any(has_std, feature = "force_std", test)))]
+pub struct IndexSet<T, S> {
     map: IndexMap<T, (), S>,
 }
 
@@ -75,6 +81,7 @@ impl<T, S> fmt::Debug for IndexSet<T, S>
     }
 }
 
+#[cfg(any(has_std, feature = "force_std", test))]
 impl<T> IndexSet<T> {
     /// Create a new set. (Does not allocate.)
     pub fn new() -> Self {

tests/equivalent_trait.rs

@@ -1,4 +1,3 @@
-
 #[macro_use] extern crate indexmap;
 
 use indexmap::Equivalent;

tests/quick.rs

@@ -1,4 +1,3 @@
-
 #[macro_use]
 extern crate quickcheck;
 

tests/tests.rs

@@ -1,4 +1,3 @@
-
 #[macro_use]
 extern crate indexmap;