Use explicit features rather than implicit.

In Rust 2024 edition, implicit features from optional dependencies
are going away and explicit features are required.

This changes all features using optional dependencies to use the
"dep:" syntax to avoid creating implicit features.

It also adds new explicit features for optional dependencies that
didn't previously have an explicit feature to enable them.

One user-visible implicit feature has now been removed:
`rand` no longer has an implicit feature `rand_chacha`
as that is enabled by `std_rng`.

CHANGELOG.md

@@ -20,6 +20,7 @@ You may also find the [Upgrade Guide](https://rust-random.github.io/book/update.
 - Fix portability of `rand::distributions::Slice` (#1469)
 - Rename `rand::distributions` to `rand::distr` (#1470)
 - The `serde1` feature has been renamed `serde` (#1477)
+- Remove implicit feature `rand_chacha`. This is enabled by `std_rng`. (#1473)
 
 ## [0.9.0-alpha.1] - 2024-03-18
 - Add the `Slice::num_choices` method to the Slice distribution (#1402)

Cargo.toml

@@ -46,7 +46,7 @@ getrandom = ["rand_core/getrandom"]
 simd_support = ["zerocopy/simd-nightly"]
 
 # Option (enabled by default): enable StdRng
-std_rng = ["rand_chacha"]
+std_rng = ["dep:rand_chacha"]
 
 # Option: enable SmallRng
 small_rng = []
@@ -56,6 +56,9 @@ small_rng = []
 # Note: enabling this option is expected to affect reproducibility of results.
 unbiased = []
 
+# Option: enable logging
+log = ["dep:log"]
+
 [workspace]
 members = [
     "rand_core",

rand_core/Cargo.toml

@@ -27,6 +27,7 @@ all-features = true
 [features]
 std = ["alloc", "getrandom?/std"]
 alloc = []  # enables Vec and Box support without std
+getrandom = ["dep:getrandom"]
 serde = ["dep:serde"] # enables serde for BlockRng wrapper
 
 [dependencies]

rand_distr/Cargo.toml

@@ -30,6 +30,7 @@ alloc = ["rand/alloc"]
 std_math = ["num-traits/std"]
 
 serde = ["dep:serde", "rand/serde"]
+serde_with = ["dep:serde_with"]
 
 [dependencies]
 rand = { path = "..", version = "=0.9.0-alpha.1", default-features = false }