Merge #71: Add "alloc" feature

85caa28 Add CI test.sh script (Tobin C. Harding)
1ceb828 Add no-allocator crate (Tobin C. Harding)
8f27962 Add "alloc" feature (Tobin C. Harding)
33bad4c Move embedded to sub-dir with-allocator (Tobin C. Harding)

Pull request description:

  We would like users to be able to use parts of this library in a `no_std` environment without an allocator. To achieve this add an "alloc" feature and feature gate any code that requires allocation behind.

  To test the new feature gating works, and catch regressions, add a crate that uses `bech32` as a dependency with no default features and forces a `no_std` build. (Does not test any code just imports the lib to verify it builds.)

  Patch 3 can be moved before patch 2 to verify that the crate does not currently build without an allocator.

  Patch 4 adds a minimal `contrib/test.sh` script.

ACKs for top commit:
  apoelstra:
    ACK 85caa28

Tree-SHA512: ee1507d08dca79ddee07e6b7188c8f707d0c0dd1aaf778f3d5b376fa5ba99358260ed034efce852366e794843737757589564cbf65fa3e2560ff73559baa06d2

Author: apoelstra

.github/workflows/rust.yml

@@ -3,7 +3,7 @@ on: [pull_request]
 name: Continuous Integration
 
 jobs:
-  test:
+  Test:
     name: Test Suite
     runs-on: ubuntu-latest
     strategy:
@@ -13,16 +13,17 @@ jobs:
           - stable
           - nightly
     steps:
+      - name: Checkout Crate
       - uses: actions/checkout@v2
+      - name: Checkout Toolchain
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
           toolchain: ${{ matrix.rust }}
           override: true
-      - uses: actions-rs/cargo@v1
-        with:
-          command: test
-          args: --verbose --features strict
+      - name: Run Test Script
+        env: ${{ matrix.rust }}
+        run: ./contrib/test.sh
 
   fmt:
     name: Rustfmt
@@ -60,7 +61,8 @@ jobs:
           command: clippy
           args: -- -D warnings
 
-  Embedded:
+  EmbeddedWithAlloc:
+    name: no_std with alloc
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
@@ -79,4 +81,20 @@ jobs:
         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 && cargo run --target thumbv7m-none-eabi
+        run: cd embedded/with-allocator && cargo run --target thumbv7m-none-eabi
+
+  EmbeddedNoAlloc:
+    name: no_std no alloc
+    runs-on: ubuntu-latest
+    strategy:
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+      - uses: actions-rs/cargo@v1
+        with:
+          command: rustc
+          args: -- -C link-arg=-nostartfiles

.gitignore

@@ -2,5 +2,7 @@
 *.o
 /Cargo.lock
 
-/embedded/Cargo.lock
-/embedded/.cargo
+/embedded/no-allocator/Cargo.lock
+/embedded/no-allocator/.cargo
+/embedded/with-allocator/Cargo.lock
+/embedded/with-allocator/.cargo

Cargo.toml

@@ -13,7 +13,9 @@ edition = "2018"
 
 [features]
 default = ["std"]
-std = []
+std = ["alloc"]
+alloc = []
+
 # Only for CI to make all warnings errors, do not activate otherwise (may break forward compatibility)
 strict = []
 

contrib/test.sh

@@ -0,0 +1,25 @@
+#!/bin/sh
+#
+# CI test script for rust-bech32.
+#
+# The "strict" feature is used to configure cargo to deny all warnings, always use it in test runs.
+
+set -ex
+
+# Sanity, check tools exist.
+cargo --version
+rustc --version
+
+# 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 "std" feature (implies "alloc").
+cargo build --no-default-features --features="strict std"
+cargo test --no-default-features --features="strict std"
+
+# Check "alloc" feature alone.
+cargo build --no-default-features --features="strict alloc"
+cargo test --no-default-features --features="strict alloc"
+
+exit 0

embedded/no-allocator/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+authors = ["Tobin C. Harding <me@tobin.cc>"]
+edition = "2018"
+readme = "README.md"
+name = "no-allocator"
+version = "0.1.0"
+
+[profile.dev]
+panic = "abort"
+
+[profile.release]
+panic = "abort"
+
+[dependencies]
+bech32 = { path = "../../", default_features = false }

embedded/no-allocator/README.md

@@ -0,0 +1,10 @@
+# no_std test crate without an allocator
+
+This crate is based on the blog post found at:
+
+ https://blog.dbrgn.ch/2019/12/24/testing-for-no-std-compatibility/
+
+Its purpose is to test that the `rust-bech32` library can be built in a `no_std` environment without
+a global allocator.
+
+Build with: `cargo rustc -- -C link-arg=-nostartfiles`.

embedded/no-allocator/src/main.rs

@@ -0,0 +1,26 @@
+//! Test `no_std` build of `bech32`.
+//!
+//! Build with: `cargo rustc -- -C link-arg=-nostartfiles`.
+//!
+
+#![no_std]
+#![no_main]
+
+use core::panic::PanicInfo;
+
+// Note: `#[global_allocator]` is NOT set.
+
+#[allow(unused_imports)]
+use bech32;
+
+/// 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 {}
+}

embedded/Cargo.toml renamed to embedded/with-allocator/Cargo.toml

@@ -2,7 +2,7 @@
 authors = ["Riccardo Casatta <riccardo@casatta.it>"]
 edition = "2018"
 readme = "README.md"
-name = "embedded"
+name = "with-allocator"
 version = "0.1.0"
 
 [dependencies]
@@ -11,10 +11,10 @@ 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 }
+bech32 = { path="../../", default-features = false }
 
 [[bin]]
-name = "embedded"
+name = "with-allocator"
 test = false
 bench = false