From d8b7d11db153a73b4e78812ba7a9c530eafca12e Mon Sep 17 00:00:00 2001
From: "Jamil Lambert, PhD" <Jamil.Lambert@proton.me>
Date: Wed, 19 Feb 2025 19:36:51 +0000
Subject: [PATCH] Add CI check for odd BufEncoder CAP

Add a test file that has an odd capacity BufEncoder.

Add a CI check that the test file does not compile.
---
 .github/workflows/README.md   |  1 +
 .github/workflows/rust.yaml   | 11 +++++++++++
 Cargo.toml                    |  2 +-
 contrib/compile-tests.sh      | 12 ++++++++++++
 tests/compiletest/Cargo.toml  |  8 ++++++++
 tests/compiletest/src/main.rs |  7 +++++++
 6 files changed, 40 insertions(+), 1 deletion(-)
 create mode 100755 contrib/compile-tests.sh
 create mode 100644 tests/compiletest/Cargo.toml
 create mode 100644 tests/compiletest/src/main.rs

diff --git a/.github/workflows/README.md b/.github/workflows/README.md
index 21f8272..ef4f912 100644
--- a/.github/workflows/README.md
+++ b/.github/workflows/README.md
@@ -24,3 +24,4 @@ Run from rust.yml unless stated otherwise. Unfortunately we are now exceeding th
 10. `Arch32bit`
 11. `Cross`
 12. `Format`
+13. `Compile tests`
diff --git a/.github/workflows/rust.yaml b/.github/workflows/rust.yaml
index b0b1bc6..311e8db 100644
--- a/.github/workflows/rust.yaml
+++ b/.github/workflows/rust.yaml
@@ -218,3 +218,14 @@ jobs:
         run: rustup component add rustfmt
       - name: "Check formatting"
         run: cargo +nightly fmt --all -- --check
+
+  Compile:
+    name: Compile tests
+    runs-on: ubuntu-latest
+    steps:
+      - name: "Checkout repo"
+        uses: actions/checkout@v4
+      - name: "Select toolchain"
+        uses: dtolnay/rust-toolchain@stable
+      - name: "Run compile tests"
+        run: ./contrib/compile-tests.sh
diff --git a/Cargo.toml b/Cargo.toml
index 47ff9df..ed25e5d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,7 +18,7 @@ all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
 
 [workspace]
-members = ["fuzz"]
+members = ["fuzz", "tests/compiletest"]
 
 [features]
 default = ["std"]
diff --git a/contrib/compile-tests.sh b/contrib/compile-tests.sh
new file mode 100755
index 0000000..c3e7283
--- /dev/null
+++ b/contrib/compile-tests.sh
@@ -0,0 +1,12 @@
+#!/bin/bash
+
+# Check that an odd BufEncoder capacity fails to compile
+
+cd tests/compiletest
+if cargo run > /dev/null 2>&1; then
+    echo "test compiled with an odd BufEncoder capacity when it shouldn't"
+    exit 1
+else
+    echo "odd BufEncoder capacity failed to compile as expected"
+    exit 0
+fi
diff --git a/tests/compiletest/Cargo.toml b/tests/compiletest/Cargo.toml
new file mode 100644
index 0000000..c691770
--- /dev/null
+++ b/tests/compiletest/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "compiletest"
+version = "0.1.0"
+edition = "2021"
+rust-version = "1.63.0"
+
+[dependencies]
+hex = { package = "hex-conservative", path = "../../" }
diff --git a/tests/compiletest/src/main.rs b/tests/compiletest/src/main.rs
new file mode 100644
index 0000000..1650880
--- /dev/null
+++ b/tests/compiletest/src/main.rs
@@ -0,0 +1,7 @@
+use hex::buf_encoder::BufEncoder;
+use hex::Case;
+
+fn main() { odd_buffer(); }
+
+// This should fail to compile because the capacity size is odd.
+fn odd_buffer() { let _encoder = BufEncoder::<3>::new(Case::Lower); }