Add/fix alloc features

Eventually we would like all our crates other than `bitcoin` to be able
to be used without an allocator. Currently, and during crate smashing,
this is not that useful because so much of the code comes from `bitcoin`
and relies on the availability of an allocator.

As an initial step, add the `alloc` feature to `addresses` , `base58`,
and `primitives`.

In order to to keep `--no-default-features` builds working make the
crates empty if the `alloc` feature is not enabled. This is a suboptimal
solution because the error messages users will get when they forget to
enable `alloc` will be confusing (eg something like primitives does not
contain Transaction). However our CI script (`run_task.sh`) expects
`--no-default-features` to build cleanly (as do I).

addresses/contrib/test_vars.sh

@@ -8,7 +8,7 @@
 FEATURES_WITH_STD=""
 
 # Test all these features without "std" enabled.
-FEATURES_WITHOUT_STD=""
+FEATURES_WITHOUT_STD="alloc"
 
 # Run these examples.
 EXAMPLES=""

addresses/src/lib.rs

@@ -5,8 +5,12 @@
 //! Bitcoin addresses do not appear on chain; rather, they are conventions used by Bitcoin (wallet)
 //! software to communicate where coins should be sent and are based on the output type e.g., P2WPKH.
 //!
+//! This crate can be used in a no-std environment but requires an allocator.
+//!
 //! ref: <https://sprovoost.nl/2022/11/10/what-is-a-bitcoin-address/>
 
+// NB: This crate is empty if `alloc` is not enabled.
+#![cfg(feature = "alloc")]
 #![cfg_attr(all(not(test), not(feature = "std")), no_std)]
 // Experimental features we need.
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]

base58/Cargo.toml

@@ -14,11 +14,12 @@ exclude = ["tests", "contrib"]
 
 [features]
 default = ["std"]
-std = ["hashes/std", "internals/std"]
+std = ["alloc", "hashes/std", "internals/std"]
+alloc = ["hashes/alloc", "internals/alloc"]
 
 [dependencies]
-hashes = { package = "bitcoin_hashes", version = "0.14.0", default-features = false, features = ["alloc"] }
+hashes = { package = "bitcoin_hashes", version = "0.14.0", default-features = false }
-internals = { package = "bitcoin-internals", version = "0.3.0", features = ["alloc"] }
+internals = { package = "bitcoin-internals", version = "0.3.0" }
 
 [dev-dependencies]
 hex = { package = "hex-conservative", version = "0.2.0", default-features = false, features = ["alloc"] }

base58/contrib/test_vars.sh

@@ -8,7 +8,7 @@
 FEATURES_WITH_STD=""
 
 # Test all these features without "std" enabled.
-FEATURES_WITHOUT_STD=""
+FEATURES_WITHOUT_STD="alloc"
 
 # Run these examples.
 EXAMPLES=""

base58/src/lib.rs

@@ -4,6 +4,8 @@
 //!
 //! This crate can be used in a no-std environment but requires an allocator.
 
+// NB: This crate is empty if `alloc` is not enabled.
+#![cfg(feature = "alloc")]
 #![no_std]
 // Experimental features we need.
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]

bitcoin/Cargo.toml

@@ -25,13 +25,13 @@ secp-recovery = ["secp256k1/recovery"]
 bitcoinconsensus-std = ["bitcoinconsensus/std", "std"]
 
 [dependencies]
-base58 = { package = "base58ck", version = "0.1.0", default-features = false }
+base58 = { package = "base58ck", version = "0.1.0", default-features = false, features = ["alloc"] }
 bech32 = { version = "0.11.0", default-features = false, features = ["alloc"] }
 hashes = { package = "bitcoin_hashes", version = "0.14.0", default-features = false, features = ["alloc", "io"] }
 hex = { package = "hex-conservative", version = "0.2.0", default-features = false, features = ["alloc"] }
 internals = { package = "bitcoin-internals", version = "0.3.0", features = ["alloc"] }
 io = { package = "bitcoin-io", version = "0.1.1", default-features = false, features = ["alloc"] }
-primitives = { package = "bitcoin-primitives", version = "0.100.0", default-features = false }
+primitives = { package = "bitcoin-primitives", version = "0.100.0", default-features = false, features = ["alloc"] }
 secp256k1 = { version = "0.29.0", default-features = false, features = ["hashes", "alloc"] }
 units = { package = "bitcoin-units", version = "0.1.0", default-features = false, features = ["alloc"] }
 

primitives/Cargo.toml

@@ -16,14 +16,15 @@ exclude = ["tests", "contrib"]
 
 [features]
 default = ["std"]
-std = ["internals/std"]
+std = ["alloc", "internals/std"]
+alloc = ["internals/alloc"]
 serde = ["actual-serde", "internals/serde"]
 
 [dependencies]
-internals = { package = "bitcoin-internals", version = "0.3.0", features = ["alloc"] }
+internals = { package = "bitcoin-internals", version = "0.3.0" }
 
 # Do NOT use this as a feature! Use the `serde` feature instead.
-actual-serde = { package = "serde", version = "1.0.103", default-features = false, features = [ "alloc" ], optional = true }
+actual-serde = { package = "serde", version = "1.0.103", default-features = false, optional = true }
 
 [dev-dependencies]
 

primitives/contrib/test_vars.sh

@@ -5,10 +5,10 @@
 # shellcheck disable=SC2034
 
 # Test these features with "std" enabled.
-FEATURES_WITH_STD=""
+FEATURES_WITH_STD="serde"
 
 # Test these features without "std" enabled.
-FEATURES_WITHOUT_STD=""
+FEATURES_WITHOUT_STD="alloc serde"
 
 # Run these examples.
 EXAMPLES=""

primitives/src/lib.rs

@@ -4,8 +4,12 @@
 //!
 //! Primitive data types that are used throughout the [`rust-bitcoin`] ecosystem.
 //!
+//! This crate can be used in a no-std environment but requires an allocator.
+//!
 //! [`rust-bitcoin`]: <https://github.com/rust-bitcoin>
 
+// NB: This crate is empty if `alloc` is not enabled.
+#![cfg(feature = "alloc")]
 #![cfg_attr(all(not(test), not(feature = "std")), no_std)]
 // Experimental features we need.
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]