ffi-seams.yml

# SPDX-License-Identifier: MPL-2.0
# Owner: Jonathan D.A. Jewell <j.d.a.jewell@open.ac.uk>
# ffi-seams.yml — contract tests for the idris2 <-> zig token-buffer ABI.
#
# Runs `zig test` on idris2/ffi/zig/seams.zig, which exercises the @ptrCast
# NUL-sentinel invariant + integer/bool marshalling + i32<->usize clamping
# across the C-ABI seam (see the header of idris2/ffi/zig/seams.zig).
#
# Convention (per the estate CI rule): NO workflow-level `on.*.paths` on a
# gate — a path-filtered required check is reported "Expected" forever and
# strands PRs as blocked. Instead an always-run `changes` job decides whether
# the heavy `test` job runs; a job skipped via `if:` counts as a passing
# required check.

name: FFI Seam Tests

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]
  workflow_dispatch:

permissions:
  contents: read

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

jobs:
  changes:
    name: Detect relevant changes
    runs-on: ubuntu-latest
    timeout-minutes: 5
    outputs:
      run: ${{ steps.detect.outputs.run }}
    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          fetch-depth: 0
      - id: detect
        env:
          EVENT: ${{ github.event_name }}
          BASE: ${{ github.base_ref }}
          BEFORE: ${{ github.event.before }}
        run: |
          # Fail-safe: default to running; only set run=false when a successful
          # diff shows nothing under idris2/ffi/zig/ changed.
          set -uo pipefail
          run=true
          if [ "$EVENT" = pull_request ]; then
            git fetch --no-tags --depth=200 origin "$BASE" 2>/dev/null \
              && changed=$(git diff --name-only "origin/${BASE}...HEAD" 2>/dev/null) \
              && { printf '%s\n' "$changed" | grep -qE '^idris2/ffi/zig/' && run=true || run=false; }
          elif [ "$EVENT" = push ] && [ -n "$BEFORE" ] && [ "$BEFORE" != 0000000000000000000000000000000000000000 ]; then
            changed=$(git diff --name-only "${BEFORE}...${GITHUB_SHA}" 2>/dev/null) \
              && { printf '%s\n' "$changed" | grep -qE '^idris2/ffi/zig/' && run=true || run=false; }
          fi
          printf 'run=%s\n' "$run" >> "$GITHUB_OUTPUT"
          echo "relevant=$run"

  test:
    name: Zig FFI seam tests
    needs: changes
    if: needs.changes.outputs.run == 'true'
    runs-on: ubuntu-latest
    timeout-minutes: 15
    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1

      - name: Install Zig
        uses: mlugg/setup-zig@d1434d08867e3ee9daa34448df10607b98908d29 # v2
        with:
          version: 0.15.2

      - name: Run token-buffer seam tests
        # -lc: tokbuf.zig allocates via std.heap.c_allocator.
        run: zig test -lc idris2/ffi/zig/seams.zig