ci: semver-check for non-additive cargo features

Co-authored-by: Predrag Gruevski <2348618+obi1kenobi@users.noreply.github.com>

.github/workflows/semver-checks.yml

@@ -4,8 +4,8 @@ on:   # yamllint disable-line rule:truthy
 name: Check semver breaks
 
 jobs:
-  API:
-    name: API - stable toolchain
+  PR:
+    name: PR Semver - nightly toolchain
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
@@ -21,7 +21,7 @@ jobs:
       - name: "Binstall cargo-semver-checks"
         run: cargo binstall cargo-semver-checks --no-confirm
       - name: "Run semver checker script"
-        run: ./contrib/check-semver.sh
+        run: ./contrib/check-semver-pr.sh
       - name: Save PR number
         if: ${{ hashFiles('semver-break') != '' }}
         env:
@@ -39,3 +39,21 @@ jobs:
         with:
           name: semver-break
           path: semver-break
+
+  Feature:
+    name: Non additive cargo features - stable toolchain
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+    steps:
+      - name: "Checkout repo"
+        uses: actions/checkout@v4
+      - name: "Install Rustup"
+        uses: dtolnay/rust-toolchain@stable
+      - name: "Install cargo-binstall"
+        uses: cargo-bins/cargo-binstall@main
+      - name: "Binstall cargo-semver-checks"
+        run: cargo binstall cargo-semver-checks --no-confirm
+      - name: "Run semver checker script"
+        run: ./contrib/check-semver-feature.sh
+

contrib/check-semver-feature.sh

@@ -0,0 +1,136 @@
+#!/usr/bin/env bash
+#
+# Checks semver compatibility between the `--no-features` and `all-features`.
+# This is important since it tests for the presence non-additive cargo features.
+#
+# Under the hood uses cargo semver-checks to check for breaking changes.
+# We cannot use it directly since it only supports checking against published
+# crates.
+# That's the intended use case for cargo semver-checks:
+# you run before publishing a new version of a crate to check semver breaks.
+# Here we are hacking it by first generating JSON files from cargo doc
+# and then using those files to check for breaking changes with
+# cargo semver-checks.
+
+set -euo pipefail
+
+# These are the hardcoded flags that cargo semver-checks uses
+# under the hood to invoke rustdoc.
+RUSTDOCFLAGS="-Z unstable-options --document-private-items --document-hidden-items --output-format=json --cap-lints=allow"
+
+main() {
+    # Generate JSON files for no-features and all-features
+    # 1. bitcoin
+    generate_json_files_all_features "bitcoin"
+    generate_json_files_no_default_features "bitcoin"
+
+    # 2. base58ck
+    generate_json_files_all_features "base58ck"
+    generate_json_files_no_default_features "base58ck"
+
+    # 3. bitcoin_hashes
+    generate_json_files_all_features "bitcoin_hashes"
+    generate_json_files_no_default_features "bitcoin_hashes"
+
+    # 4. bitcoin-units
+    generate_json_files_all_features "bitcoin-units"
+    generate_json_files_no_default_features "bitcoin-units"
+
+    # 5. bitcoin-io
+    generate_json_files_all_features "bitcoin-io"
+    generate_json_files_no_default_features "bitcoin-io"
+
+    # Check for API semver non-addivite cargo features on all the generated JSON files above.
+    run_cargo_semver_check "bitcoin"
+    run_cargo_semver_check "base58ck"
+    run_cargo_semver_check "bitcoin_hashes"
+    run_cargo_semver_check "bitcoin-units"
+    run_cargo_semver_check "bitcoin-io"
+
+    # Invoke cargo semver-checks to check for non-additive cargo features
+    # in all generated files.
+    check_for_non_additive_cargo_features
+}
+
+# Run cargo doc with the cargo semver-checks rustdoc flags.
+# We don't care about dependencies.
+run_cargo_doc() {
+    RUSTDOCFLAGS="$RUSTDOCFLAGS" RUSTC_BOOTSTRAP=1 cargo doc --no-deps "$@"
+}
+
+# Run cargo semver-check
+run_cargo_semver_check() {
+    local crate="$1"
+
+    echo "Running cargo semver-checks for $crate"
+    # Hack to not fail on errors.
+    # This is necessary since cargo semver-checks will fail if the
+    # semver check fails.
+    # We check that manually later.
+    set +e
+    cargo semver-checks -v --baseline-rustdoc "$crate-no-default-features.json" --current-rustdoc "$crate-all-features.json" > "$crate--additive-features.txt" 2>&1
+    set -e
+}
+
+# The following function uses cargo doc to generate JSON files that
+# cargo semver-checks can use.
+# - no-default-features: generate JSON doc files with no default features.
+generate_json_files_no_default_features() {
+    local crate="$1"
+
+    echo "Running cargo doc no-default-features for $crate"
+    run_cargo_doc --no-default-features -p "$crate"
+
+    # replace _ for - in crate name.
+    # This is necessary since some crates have - in their name
+    # which will be converted to _ in the output file by cargo doc.
+    mv "target/doc/${crate//-/_}.json" "$crate-no-default-features.json"
+}
+# - all-features: generate JSON doc files with all features.
+generate_json_files_all_features() {
+    local crate="$1"
+
+    echo "Running cargo doc all-features for $crate"
+    run_cargo_doc --all-features -p "$crate"
+
+    # replace _ for - in crate name.
+    # This is necessary since some crates have - in their name
+    # which will be converted to _ in the output file by cargo doc.
+    mv -v "target/doc/${crate//-/_}.json" "$crate-all-features.json"
+}
+
+# Check if there are non-additive cargo features.
+# We loop through all the generated files and check if there is a FAIL
+# in the cargo semver-checks output.
+# If we detect a fail, we create an empty file non-additive-cargo.
+# If the following CI step finds this file, it will add:
+# 1. a comment on the PR.
+# 2. a label to the PR.
+check_for_non_additive_cargo_features() {
+    for file in *additive-features.txt; do
+        echo "Checking $file"
+        if grep -q "FAIL" "$file"; then
+            echo "You have introduced non-additive cargo features"
+            echo "FAIL found in $file"
+            # flag it as a breaking change
+            # Handle the case where FAIL is found
+            touch non-additive-cargo
+        fi
+    done
+    if ! [ -f non-additive-cargo ]; then
+       echo "No non-additive cargo features found"
+    else
+        err "Non-additive cargo features found"
+    fi
+}
+
+err() {
+    echo "$1" >&2
+    exit 1
+}
+
+#
+# Main script
+#
+main "$@"
+exit 0