Adapt lightning-invoice to no_std

Author: devrandom

.github/workflows/build.yml

@@ -115,6 +115,11 @@ jobs:
           # check if there is a conflict between no-std and the default std feature
           cargo test --verbose --color always --features no-std
           cd ..
+          cd lightning-invoice
+          cargo test --verbose --color always --no-default-features --features no-std
+          # check if there is a conflict between no-std and the default std feature
+          cargo test --verbose --color always --features no-std
+          cd ..
       - name: Test on no-std builds Rust ${{ matrix.toolchain }} and full code-linking for coverage generation
         if: "matrix.build-no-std && matrix.coverage"
         run: |

lightning-invoice/Cargo.toml

@@ -8,13 +8,20 @@ license = "MIT OR Apache-2.0"
 keywords = [ "lightning", "bitcoin", "invoice", "BOLT11" ]
 readme = "README.md"
 
+[features]
+default = ["std"]
+no-std = ["hashbrown", "lightning/no-std", "core2/alloc"]
+std = ["bitcoin_hashes/std", "num-traits/std", "lightning/std"]
+
 [dependencies]
 bech32 = "0.8"
-lightning = { version = "0.0.104", path = "../lightning" }
-secp256k1 = { version = "0.20", features = ["recovery"] }
-num-traits = "0.2.8"
-bitcoin_hashes = "0.10"
+lightning = { version = "0.0.104", path = "../lightning", default-features = false }
+secp256k1 = { version = "0.20", default-features = false, features = ["recovery", "alloc"] }
+num-traits = { version = "0.2.8", default-features = false }
+bitcoin_hashes = { version = "0.10", default-features = false }
+hashbrown = { version = "0.11", optional = true }
+core2 = { version = "0.3.0", default-features = false, optional = true }
 
 [dev-dependencies]
+lightning = { version = "0.0.104", path = "../lightning", default-features = false, features = ["_test_utils"] }
 hex = "0.3"
-lightning = { version = "0.0.104", path = "../lightning", features = ["_test_utils"] }

lightning-invoice/src/de.rs

@@ -1,15 +1,17 @@
+#[cfg(feature = "std")]
 use std::error;
-use std::fmt;
-use std::fmt::{Display, Formatter};
-use std::num::ParseIntError;
-use std::str;
-use std::str::FromStr;
+use core::fmt;
+use core::fmt::{Display, Formatter};
+use core::num::ParseIntError;
+use core::str;
+use core::str::FromStr;
 
 use bech32;
 use bech32::{u5, FromBase32};
 
 use bitcoin_hashes::Hash;
 use bitcoin_hashes::sha256;
+use crate::prelude::*;
 use lightning::ln::PaymentSecret;
 use lightning::routing::network_graph::RoutingFees;
 use lightning::routing::router::{RouteHint, RouteHintHop};
@@ -28,7 +30,7 @@ use self::hrp_sm::parse_hrp;
 
 /// State machine to parse the hrp
 mod hrp_sm {
-	use std::ops::Range;
+	use core::ops::Range;
 
 	#[derive(PartialEq, Eq, Debug)]
 	enum States {
@@ -723,8 +725,10 @@ impl Display for ParseOrSemanticError {
 	}
 }
 
+#[cfg(feature = "std")]
 impl error::Error for ParseError {}
 
+#[cfg(feature = "std")]
 impl error::Error for ParseOrSemanticError {}
 
 macro_rules! from_error {