bitcoin: Use no_std attribute

As we do for other crates; default to `no_std`.

The major issues with this is that we have, up until now, assumed we
have `extern crate std` in tests. Most of this patch is fixing the
feature gating to use stuff from `extern crate alloc` and correctly
feature gating on "std" if required.

bitcoin/src/bip158.rs

@@ -561,17 +561,20 @@ impl<'a, W: Write> BitStreamWriter<'a, W> {
 
 #[cfg(test)]
 mod test {
-    use std::collections::HashMap;
-
     use hex::test_hex_unwrap as hex;
-    use serde_json::Value;
 
     use super::*;
-    use crate::consensus::encode::deserialize;
-    use crate::ScriptBuf;
 
     #[test]
+    #[cfg(feature = "std")]
     fn test_blockfilters() {
+        use std::collections::HashMap;
+
+        use serde_json::Value;
+
+        use crate::consensus::encode::deserialize;
+        use crate::ScriptBuf;
+
         // test vectors from: https://github.com/jimpo/bitcoin/blob/c7efb652f3543b001b4dd22186a354605b14f47e/src/test/data/blockfilters.json
         let data = include_str!("../tests/data/blockfilters.json");
 

bitcoin/src/blockdata/block.rs

@@ -670,6 +670,8 @@ mod benches {
 
     use super::Block;
     use crate::consensus::{deserialize, Decodable, Encodable};
+    #[allow(unused_imports)] // Less maintenance to just import this in tests.
+    use crate::prelude::*;
 
     #[bench]
     pub fn bench_stream_reader(bh: &mut Bencher) {

bitcoin/src/blockdata/constants.rs

@@ -200,6 +200,8 @@ mod test {
     use super::*;
     use crate::consensus::encode::serialize;
     use crate::consensus::params;
+    #[allow(unused_imports)] // Less maintenance to just import this in tests.
+    use crate::prelude::*;
 
     #[test]
     fn bitcoin_genesis_first_transaction() {

bitcoin/src/blockdata/mod.rs

@@ -29,6 +29,8 @@ pub mod fee_rate {
     #[cfg(test)]
     mod tests {
         use super::*;
+        #[allow(unused_imports)] // Less maintenance to just import this in tests.
+        use crate::prelude::*;
 
         #[test]
         fn fee_convenience_functions_agree() {

bitcoin/src/blockdata/opcodes.rs

@@ -541,10 +541,9 @@ impl Ordinary {
 
 #[cfg(test)]
 mod tests {
-    use std::collections::HashSet;
-
     use super::*;
 
+    #[cfg(feature = "std")]
     macro_rules! roundtrip {
         ($unique:expr, $op:ident) => {
             assert_eq!($op, Opcode::from($op.to_u8()));
@@ -631,7 +630,10 @@ mod tests {
     }
 
     #[test]
+    #[cfg(feature = "std")]
     fn str_roundtrip() {
+        use std::collections::HashSet;
+
         let mut unique = HashSet::new();
         roundtrip!(unique, OP_PUSHBYTES_0);
         roundtrip!(unique, OP_PUSHBYTES_1);

bitcoin/src/blockdata/transaction.rs

@@ -2039,7 +2039,7 @@ mod tests {
     }
 
     #[test]
-    #[cfg(feature = "bitcoinconsensus")]
+    #[cfg(all(feature = "bitcoinconsensus", feature = "std"))]
     fn transaction_verify() {
         use std::collections::HashMap;
 
@@ -2433,9 +2433,10 @@ mod tests {
     }
 
     #[test]
+    #[cfg(feature = "std")]
     fn sequence_debug_output() {
         let seq = Sequence::from_seconds_floor(1000);
-        println!("{:?}", seq)
+        std::println!("{:?}", seq)
     }
 
     #[test]
@@ -2470,6 +2471,8 @@ mod benches {
 
     use super::Transaction;
     use crate::consensus::{deserialize, Encodable};
+    #[allow(unused_imports)] // Less maintenance to just import this in tests.
+    use crate::prelude::*;
 
     const SOME_TX: &str = "0100000001a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff0100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000";
 

bitcoin/src/blockdata/witness.rs

@@ -567,13 +567,14 @@ mod test {
     }
 
     #[test]
+    #[cfg(feature = "std")]
     fn witness_debug_can_display_empty_instruction() {
         let witness = Witness {
             witness_elements: 1,
             content: append_u32_vec(vec![], &[0]),
             indices_start: 2,
         };
-        println!("{:?}", witness);
+        std::println!("{:?}", witness);
     }
 
     #[test]

bitcoin/src/crypto/sighash.rs

@@ -1448,14 +1448,14 @@ impl<E: std::error::Error + 'static> std::error::Error for SigningDataError<E> {
 
 #[cfg(test)]
 mod tests {
-    use std::str::FromStr;
-
     use hashes::HashEngine;
     use hex::{test_hex_unwrap as hex, FromHex};
 
     use super::*;
     use crate::blockdata::locktime::absolute;
     use crate::consensus::deserialize;
+    #[allow(unused_imports)] // Less maintenance to just import this in tests.
+    use crate::prelude::*;
 
     extern crate serde_json;
 
@@ -1770,6 +1770,8 @@ mod tests {
     #[cfg(feature = "serde")]
     #[test]
     fn bip_341_sighash_tests() {
+        use core::str::FromStr;
+
         use hex::DisplayHex;
 
         fn sighash_deser_numeric<'de, D>(deserializer: D) -> Result<TapSighashType, D::Error>
@@ -1962,6 +1964,8 @@ mod tests {
 
     #[test]
     fn sighashtype_fromstr_display() {
+        use core::str::FromStr;
+
         let sighashtypes = vec![
             ("SIGHASH_DEFAULT", TapSighashType::Default),
             ("SIGHASH_ALL", TapSighashType::All),

bitcoin/src/hash_types.rs

@@ -14,6 +14,8 @@ pub use crate::{
 mod tests {
     use super::*;
     use crate::hashes::Hash;
+    #[allow(unused_imports)] // Less maintenance to just import this in tests.
+    use crate::prelude::*;
     use crate::{
         LegacySighash, PubkeyHash, ScriptHash, SegwitV0Sighash, TapSighash, WPubkeyHash,
         WScriptHash, XKeyIdentifier,

bitcoin/src/lib.rs

@@ -29,7 +29,7 @@
 //!                            happen the implementations diverge one day.
 //! * `ordered` - (dependency), adds implementations of `ArbitraryOrdOrd` to some structs.
 
-#![cfg_attr(all(not(feature = "std"), not(test)), no_std)]
+#![no_std]
 // Experimental features we need.
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
 #![cfg_attr(bench, feature(test))]
@@ -55,6 +55,9 @@ extern crate test;
 #[macro_use]
 extern crate alloc;
 
+#[cfg(feature = "std")]
+extern crate std;
+
 #[cfg(feature = "base64")]
 /// Encodes and decodes base64 as bytes or utf8.
 pub extern crate base64;
@@ -141,22 +144,23 @@ pub use crate::{
     taproot::{TapBranchTag, TapLeafHash, TapLeafTag, TapNodeHash, TapTweakHash, TapTweakTag},
 };
 
+/// The `rust-bitcoin` crate requires an allocator.
 #[rustfmt::skip]
 #[allow(unused_imports)]
 mod prelude {
-    #[cfg(all(not(feature = "std"), not(test)))]
+    #[cfg(not(feature = "std"))]
     pub use alloc::{string::{String, ToString}, vec::Vec, boxed::Box, borrow::{Borrow, BorrowMut, Cow, ToOwned}, slice, rc};
 
-    #[cfg(all(not(feature = "std"), not(test), any(not(rust_v_1_60), target_has_atomic = "ptr")))]
+    #[cfg(all(not(feature = "std"), any(not(rust_v_1_60), target_has_atomic = "ptr")))]
     pub use alloc::sync;
 
-    #[cfg(any(feature = "std", test))]
+    #[cfg(feature = "std")]
     pub use std::{string::{String, ToString}, vec::Vec, boxed::Box, borrow::{Borrow, BorrowMut, Cow, ToOwned}, rc, sync};
 
-    #[cfg(all(not(feature = "std"), not(test)))]
+    #[cfg(not(feature = "std"))]
     pub use alloc::collections::{BTreeMap, BTreeSet, btree_map, BinaryHeap};
 
-    #[cfg(any(feature = "std", test))]
+    #[cfg(feature = "std")]
     pub use std::collections::{BTreeMap, BTreeSet, btree_map, BinaryHeap};
 
     pub use crate::io::sink;

bitcoin/src/network.rs

@@ -310,6 +310,8 @@ mod tests {
     use super::Network;
     use crate::consensus::encode::{deserialize, serialize};
     use crate::p2p::ServiceFlags;
+    #[allow(unused_imports)] // Less maintenance to just import this in tests.
+    use crate::prelude::*;
 
     #[test]
     fn serialize_test() {

bitcoin/src/p2p/address.rs

@@ -13,6 +13,7 @@ use io::{BufRead, Read, Write};
 
 use crate::consensus::encode::{self, Decodable, Encodable, ReadExt, VarInt, WriteExt};
 use crate::p2p::ServiceFlags;
+use crate::prelude::*;
 
 /// A message which can be sent on the Bitcoin network
 #[derive(Clone, PartialEq, Eq, Hash)]
@@ -311,6 +312,8 @@ mod test {
     use super::{AddrV2, AddrV2Message, Address};
     use crate::consensus::encode::{deserialize, serialize};
     use crate::p2p::ServiceFlags;
+    #[allow(unused_imports)] // Less maintenance to just import this in tests.
+    use crate::prelude::*;
 
     #[test]
     fn serialize_address_test() {

bitcoin/src/p2p/message_blockdata.rs

@@ -14,6 +14,7 @@ use crate::blockdata::transaction::{Txid, Wtxid};
 use crate::consensus::encode::{self, Decodable, Encodable};
 use crate::internal_macros::impl_consensus_encoding;
 use crate::p2p;
+use crate::prelude::*;
 
 /// An inventory item.
 #[derive(PartialEq, Eq, Clone, Debug, Copy, Hash, PartialOrd, Ord)]
@@ -150,6 +151,8 @@ mod tests {
 
     use super::{GetBlocksMessage, GetHeadersMessage};
     use crate::consensus::encode::{deserialize, serialize};
+    #[allow(unused_imports)] // Less maintenance to just import this in tests.
+    use crate::prelude::*;
 
     #[test]
     fn getblocks_message_test() {

bitcoin/src/p2p/message_bloom.rs

@@ -9,6 +9,7 @@ use io::{BufRead, Write};
 
 use crate::consensus::{encode, Decodable, Encodable, ReadExt};
 use crate::internal_macros::impl_consensus_encoding;
+use crate::prelude::*;
 
 /// `filterload` message sets the current bloom filter
 #[derive(Clone, PartialEq, Eq, Debug)]

bitcoin/src/p2p/message_filter.rs

@@ -8,6 +8,7 @@
 use crate::bip158::{FilterHash, FilterHeader};
 use crate::blockdata::block::BlockHash;
 use crate::internal_macros::impl_consensus_encoding;
+use crate::prelude::*;
 
 /// getcfilters message
 #[derive(PartialEq, Eq, Clone, Debug)]

bitcoin/src/p2p/message_network.rs

@@ -155,6 +155,8 @@ mod tests {
     use super::{Reject, RejectReason, VersionMessage};
     use crate::consensus::encode::{deserialize, serialize};
     use crate::p2p::ServiceFlags;
+    #[allow(unused_imports)] // Less maintenance to just import this in tests.
+    use crate::prelude::*;
 
     #[test]
     fn version_message_test() {

bitcoin/src/pow.rs

@@ -1040,6 +1040,8 @@ impl kani::Arbitrary for U256 {
 #[cfg(test)]
 mod tests {
     use super::*;
+    #[allow(unused_imports)] // Less maintenance to just import this in tests.
+    use crate::prelude::*;
 
     impl<T: Into<u128>> From<T> for Target {
         fn from(x: T) -> Self { Self(U256::from(x)) }
@@ -1710,7 +1712,7 @@ mod tests {
 
     #[test]
     fn target_is_met_by_for_target_equals_hash() {
-        use std::str::FromStr;
+        use core::str::FromStr;
 
         use hashes::Hash;
 

bitcoin/src/psbt/mod.rs

@@ -1568,7 +1568,7 @@ mod tests {
 
     mod bip_vectors {
         #[cfg(feature = "base64")]
-        use std::str::FromStr;
+        use core::str::FromStr;
 
         use super::*;
         use crate::psbt::map::Map;

bitcoin/src/sign_message.rs

@@ -210,6 +210,8 @@ pub fn signed_msg_hash(msg: &str) -> sha256d::Hash {
 #[cfg(test)]
 mod tests {
     use super::*;
+    #[allow(unused_imports)] // Less maintenance to just import this in tests.
+    use crate::prelude::*;
 
     #[test]
     fn test_signed_msg_hash() {

bitcoin/tests/bip_174.rs

@@ -1,8 +1,10 @@
 //! Tests PSBT integration vectors from BIP 174
 //! defined at <https://github.com/bitcoin/bips/blob/master/bip-0174.mediawiki#test-vectors>
 
+#![cfg(feature = "std")]
+
+use core::str::FromStr;
 use std::collections::BTreeMap;
-use std::str::FromStr;
 
 use bitcoin::bip32::{Fingerprint, IntoDerivationPath, KeySource, Xpriv, Xpub};
 use bitcoin::blockdata::opcodes::OP_0;

bitcoin/tests/psbt-sign-taproot.rs

@@ -1,7 +1,7 @@
-#![cfg(not(feature = "rand-std"))]
+#![cfg(all(not(feature = "rand-std"), feature = "std"))]
 
+use core::str::FromStr;
 use std::collections::BTreeMap;
-use std::str::FromStr;
 
 use bitcoin::bip32::{DerivationPath, Fingerprint};
 use bitcoin::consensus::encode::serialize_hex;

bitcoin/tests/serde.rs

@@ -20,10 +20,10 @@
 //  let mut file = File::create("/tmp/script_bincode").unwrap();
 //  file.write_all(&got).unwrap();
 
-#![cfg(feature = "serde")]
+#![cfg(all(feature = "serde", feature = "std"))]
 
+use core::str::FromStr;
 use std::collections::BTreeMap;
-use std::str::FromStr;
 
 use bincode::serialize;
 use bitcoin::bip32::{ChildNumber, KeySource, Xpriv, Xpub};