Always use an explicit feature for std

Author: cuviper

Cargo.toml

@@ -14,9 +14,6 @@ rust-version = "1.56"
 [lib]
 bench = false
 
-[build-dependencies]
-autocfg = "1"
-
 [dependencies]
 serde = { version = "1.0", optional = true, default-features = false }
 rayon = { version = "1.4.1", optional = true }
@@ -40,7 +37,7 @@ fxhash = "0.2.1"
 serde_derive = "1.0"
 
 [features]
-# Force the use of `std`, bypassing target detection.
+default = ["std"]
 std = []
 
 # for testing only, of course

build.rs

@@ -61,13 +61,12 @@
 //!
 //! ## No Standard Library Targets
 //!
-//! This crate supports being built without `std`, requiring
-//! `alloc` instead. This is enabled automatically when it is detected that
-//! `std` is not available. There is no crate feature to enable/disable to
-//! trigger this. It can be tested by building for a std-less target.
+//! This crate supports being built without `std`, requiring `alloc` instead.
+//! This is chosen by disabling the default "std" cargo feature, by adding
+//! `default-features = false` to your dependency specification.
 //!
 //! - Creating maps and sets using [`new`][IndexMap::new] and
-//! [`with_capacity`][IndexMap::with_capacity] is unavailable without `std`.  
+//! [`with_capacity`][IndexMap::with_capacity] is unavailable without `std`.
 //!   Use methods [`IndexMap::default`][def],
 //!   [`with_hasher`][IndexMap::with_hasher],
 //!   [`with_capacity_and_hasher`][IndexMap::with_capacity_and_hasher] instead.
@@ -79,7 +78,7 @@
 
 extern crate alloc;
 
-#[cfg(has_std)]
+#[cfg(feature = "std")]
 #[macro_use]
 extern crate std;
 

src/lib.rs

@@ -1,4 +1,4 @@
-#[cfg(has_std)]
+#[cfg(feature = "std")]
 #[macro_export]
 /// Create an `IndexMap` from a list of key-value pairs
 ///
@@ -35,7 +35,7 @@ macro_rules! indexmap {
     };
 }
 
-#[cfg(has_std)]
+#[cfg(feature = "std")]
 #[macro_export]
 /// Create an `IndexSet` from a list of values
 ///

src/macros.rs

@@ -16,7 +16,7 @@ use ::core::iter::{FromIterator, FusedIterator};
 use ::core::ops::{Index, IndexMut, RangeBounds};
 use ::core::slice::{Iter as SliceIter, IterMut as SliceIterMut};
 
-#[cfg(has_std)]
+#[cfg(feature = "std")]
 use std::collections::hash_map::RandomState;
 
 use self::core::IndexMapCore;
@@ -67,12 +67,12 @@ pub use self::core::{Entry, OccupiedEntry, VacantEntry};
 /// assert_eq!(letters[&'u'], 1);
 /// assert_eq!(letters.get(&'y'), None);
 /// ```
-#[cfg(has_std)]
+#[cfg(feature = "std")]
 pub struct IndexMap<K, V, S = RandomState> {
     pub(crate) core: IndexMapCore<K, V>,
     hash_builder: S,
 }
-#[cfg(not(has_std))]
+#[cfg(not(feature = "std"))]
 pub struct IndexMap<K, V, S> {
     pub(crate) core: IndexMapCore<K, V>,
     hash_builder: S,
@@ -140,7 +140,7 @@ where
     }
 }
 
-#[cfg(has_std)]
+#[cfg(feature = "std")]
 impl<K, V> IndexMap<K, V> {
     /// Create a new map. (Does not allocate.)
     #[inline]
@@ -1391,7 +1391,7 @@ where
     }
 }
 
-#[cfg(all(has_std, rustc_1_51))]
+#[cfg(feature = "std")]
 impl<K, V, const N: usize> From<[(K, V); N]> for IndexMap<K, V, RandomState>
 where
     K: Hash + Eq,
@@ -1906,7 +1906,7 @@ mod tests {
     }
 
     #[test]
-    #[cfg(all(has_std, rustc_1_51))]
+    #[cfg(feature = "std")]
     fn from_array() {
         let map = IndexMap::from([(1, 2), (3, 4)]);
         let mut expected = IndexMap::new();

src/map.rs

@@ -3,7 +3,7 @@
 #[cfg(feature = "rayon")]
 pub use crate::rayon::set as rayon;
 
-#[cfg(has_std)]
+#[cfg(feature = "std")]
 use std::collections::hash_map::RandomState;
 
 use crate::vec::{self, Vec};
@@ -59,11 +59,11 @@ type Bucket<T> = super::Bucket<T, ()>;
 /// assert!(letters.contains(&'u'));
 /// assert!(!letters.contains(&'y'));
 /// ```
-#[cfg(has_std)]
+#[cfg(feature = "std")]
 pub struct IndexSet<T, S = RandomState> {
     pub(crate) map: IndexMap<T, (), S>,
 }
-#[cfg(not(has_std))]
+#[cfg(not(feature = "std"))]
 pub struct IndexSet<T, S> {
     pub(crate) map: IndexMap<T, (), S>,
 }
@@ -124,7 +124,7 @@ where
     }
 }
 
-#[cfg(has_std)]
+#[cfg(feature = "std")]
 impl<T> IndexSet<T> {
     /// Create a new set. (Does not allocate.)
     pub fn new() -> Self {
@@ -888,7 +888,7 @@ where
     }
 }
 
-#[cfg(all(has_std, rustc_1_51))]
+#[cfg(feature = "std")]
 impl<T, const N: usize> From<[T; N]> for IndexSet<T, RandomState>
 where
     T: Eq + Hash,
@@ -1882,7 +1882,7 @@ mod tests {
     }
 
     #[test]
-    #[cfg(all(has_std, rustc_1_51))]
+    #[cfg(feature = "std")]
     fn from_array() {
         let set1 = IndexSet::from([1, 2, 3, 4]);
         let set2: IndexSet<_> = [1, 2, 3, 4].into();

src/set.rs

@@ -4,7 +4,9 @@ version = "0.1.0"
 publish = false
 edition = "2021"
 
-[dependencies]
-indexmap = { path = "..", features = ["serde"] }
+[dependencies.indexmap]
+path = ".."
+default-features = false
+features = ["serde"]
 
 [dev-dependencies]