Merge #45: Expand the amount of core-only

32c87da Allow doing more things without alloc (John Ericson)

Pull request description:

ACKs for top commit:
  apoelstra:
    ACK 32c87da

Tree-SHA512: eac2103059fcd688690947d5817dbf758fcb99c82ec83354aa2e82113b6f5f2487e28864efc9ab2cdeb978d832d9dcbfe08208ec9f935bd356a430cff3536023

Author: apoelstra

.github/workflows/rust.yml

@@ -88,7 +88,14 @@ jobs:
     steps:
       - name: Checkout Crate
         uses: actions/checkout@v3
+      - name: Set up QEMU
+        run: sudo apt update && sudo apt install -y qemu-system-arm gcc-arm-none-eabi
       - name: Checkout Toolchain
-        uses: dtolnay/rust-toolchain@stable
+        uses: dtolnay/rust-toolchain@nightly
+        with:
+          targets: thumbv7m-none-eabi
       - name: Run
-        run: cd embedded/no-allocator && cargo rustc -- -C link-arg=-nostartfiles
+        env:
+          RUSTFLAGS: "-C link-arg=-Tlink.x"
+          CARGO_TARGET_THUMBV7M_NONE_EABI_RUNNER: "qemu-system-arm -cpu cortex-m3 -machine mps2-an385 -nographic -semihosting-config enable=on,target=native -kernel"
+        run: cd embedded/no-allocator && cargo run --target thumbv7m-none-eabi

Cargo.toml

@@ -19,4 +19,7 @@ alloc = []
 # Only for CI to make all warnings errors, do not activate otherwise (may break forward compatibility)
 strict = []
 
-[dependencies]
+[dependencies.arrayvec]
+version = "0.7.1"
+default-features = false
+optional = true

contrib/test.sh

@@ -4,28 +4,31 @@
 #
 # The "strict" feature is used to configure cargo to deny all warnings, always use it in test runs.
 
-set -ex
-
-FEATURES="std alloc"
+set -eu
+set -x
 
 # Some tests require certain toolchain types.
 NIGHTLY=false
+MIN_VERSION=false
 if cargo --version | grep nightly; then
     NIGHTLY=true
 fi
+if cargo --version | grep 1.41; then
+    MIN_VERSION=true
+fi
 
 # Sanity, check tools exist.
 cargo --version
 rustc --version
 
 # Run the linter if told to.
-if [ "$DO_LINT" = true ]
+if [ "${DO_LINT-false}" = true ]
 then
     cargo clippy --all-features --all-targets -- -D warnings
 fi
 
 # Run formatter if told to.
-if [ "$DO_FMT" = true ]; then
+if [ "${DO_FMT-false}" = true ]; then
     if [ "$NIGHTLY" = false ]; then
         echo "DO_FMT requires a nightly toolchain (consider using RUSTUP_TOOLCHAIN)"
         exit 1
@@ -34,16 +37,34 @@ if [ "$DO_FMT" = true ]; then
     cargo fmt --check
 fi
 
+check () {
+    cargo build --no-default-features --features="strict $1"
+    cargo test --no-default-features --features="strict $1"
+}
+
 # Check without features ("strict" is a CI feature only, see above).
-cargo build --no-default-features --features="strict"
-cargo test --no-default-features --features="strict"
+check ""
 
-# Check "std" feature (implies "alloc", so this is equivalent to --all-features).
-cargo build --no-default-features --features="strict std"
-cargo test --no-default-features --features="strict std"
+# Check "arrayvec" feature alone.
+if [ "$MIN_VERSION" != true ]; then
+    check "arrayvec"
+fi
 
 # Check "alloc" feature alone.
-cargo build --no-default-features --features="strict alloc"
-cargo test --no-default-features --features="strict alloc"
+check "alloc"
+
+# Check "alloc" & "arrayvec" features together.
+if [ "$MIN_VERSION" != true ]; then
+    check "alloc arrayvec"
+fi
+
+# Check "std" feature (implies "alloc", so this is equivalent to --all-features).
+cargo build --no-default-features --features="std"
+cargo test --no-default-features --features="std"
+
+# Check "std" & "arrayvec" features together.
+if [ "$MIN_VERSION" != true ]; then
+    check "std arrayvec"
+fi
 
 exit 0

embedded/README.md

@@ -0,0 +1,11 @@
+## Embedded tests
+
+These no-std tests are a bit peculiar.
+They are cross compiled to ARM and run in an emulator.
+Here's why:
+
+ - We want to build for an exotic platform to help make sure `std` doesn't sneak in by accident.
+
+ - We use an emulator and build something runnable,
+   rather than merely testing whether a library builds,
+   because we want to actually run our integration test.

embedded/no-allocator/Cargo.toml

@@ -5,11 +5,21 @@ readme = "README.md"
 name = "no-allocator"
 version = "0.1.0"
 
+[dependencies]
+cortex-m = "0.6.0"
+cortex-m-rt = "0.6.10"
+cortex-m-semihosting = "0.3.3"
+panic-halt = "0.2.0"
+arrayvec = { version = "0.7.1", default-features = false }
+bech32 = { path = "../../", default-features = false, features = ["arrayvec"] }
+
+[[bin]]
+name = "no-allocator"
+test = false
+bench = false
+
 [profile.dev]
 panic = "abort"
 
 [profile.release]
 panic = "abort"
-
-[dependencies]
-bech32 = { path = "../../", default_features = false }

embedded/no-allocator/README.md

@@ -0,0 +1,6 @@
+MEMORY
+{
+
+  FLASH : ORIGIN = 0x00000000, LENGTH = 256K
+  RAM : ORIGIN = 0x20000000, LENGTH = 64K
+}

embedded/no-allocator/memory.x

@@ -3,24 +3,52 @@
 //! Build with: `cargo rustc -- -C link-arg=-nostartfiles`.
 //!
 
-#![no_std]
+#![feature(alloc_error_handler)]
 #![no_main]
+#![no_std]
+
+use panic_halt as _;
 
-use core::panic::PanicInfo;
+use arrayvec::{ArrayString, ArrayVec};
+use bech32::{self, u5, ComboError, FromBase32, ToBase32, Variant};
+use cortex_m_rt::entry;
+use cortex_m_semihosting::{debug, hprintln};
 
 // Note: `#[global_allocator]` is NOT set.
 
-#[allow(unused_imports)]
-use bech32;
+#[entry]
+fn main() -> ! {
+    let mut encoded = ArrayString::<30>::new();
+
+    let mut base32 = ArrayVec::<u5, 30>::new();
+
+    [0x00u8, 0x01, 0x02].write_base32(&mut base32).unwrap();
+
+    bech32::encode_to_fmt_anycase(&mut encoded, "bech32", &base32, Variant::Bech32)
+        .unwrap()
+        .unwrap();
+    test(&*encoded == "bech321qqqsyrhqy2a");
+
+    hprintln!("{}", encoded).unwrap();
+
+    let mut decoded = ArrayVec::<u5, 30>::new();
+
+    let mut scratch = ArrayVec::<u5, 30>::new();
+
+    let (hrp, data, variant) =
+        bech32::decode_lowercase::<ComboError, _, _>(&encoded, &mut decoded, &mut scratch).unwrap();
+    test(hrp == "bech32");
+    let res = ArrayVec::<u8, 30>::from_base32(&data).unwrap();
+    test(&res == [0x00, 0x01, 0x02].as_ref());
+    test(variant == Variant::Bech32);
+
+    debug::exit(debug::EXIT_SUCCESS);
 
-/// This function is called on panic, defining this ensures build will fail if `std` is enabled
-/// because `panic` will be defined twice.
-#[panic_handler]
-fn panic(_info: &PanicInfo) -> ! {
     loop {}
 }
 
-#[no_mangle]
-pub extern "C" fn _start() -> ! {
-    loop {}
+fn test(result: bool) {
+    if !result {
+        debug::exit(debug::EXIT_FAILURE);
+    }
 }

embedded/no-allocator/src/main.rs

@@ -11,7 +11,7 @@ cortex-m-rt = "0.6.10"
 cortex-m-semihosting = "0.3.3"
 panic-halt = "0.2.0"
 alloc-cortex-m = "0.4.1"
-bech32 = { path="../../", default-features = false, features = ["alloc"] }
+bech32 = { path = "../../", default-features = false, features = ["alloc"] }
 
 [[bin]]
 name = "with-allocator"