Add support for actions CI.

.github/check-installable/action.yml

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+name: Check if package is installable
+inputs:
+  opam:
+    required: true
+  package:
+    reauired: true
+outputs:
+  installable:
+    description: "Is the package installable?"
+    value: ${{ steps.installable.outputs.installable }}
+runs:
+  using: composite
+  steps:
+    - name: Get opam cli option
+      id: cli
+      shell: sh
+      run: |
+        if [ "${{ inputs.opam }}" = "opam-2.1" ]; then
+          echo '##[set-output name=cli]--cli=2.1'
+        fi
+    - name: Check if package is installable
+      id: installable
+      shell: sh
+      run: |
+        if opam ${{ steps.cli.outputs.cli }} list --readonly --external --resolve=${{ inputs.package }} >/dev/null 2>&1; then
+          echo '##[set-output name=installable]true';
+        else
+          echo "Package is not installable";
+        fi
+    - name: Annotate result
+      if: ${{ !steps.installable.outputs.installable }}
+      uses: actions/github-script@v5
+      with:
+        script: |
+          core.notice('${{ inputs.package }} is not installable');

.github/install-ocaml/action.yml

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+name: Install OCaml
+inputs:
+  compiler:
+    reauired: true
+runs:
+  using: composite
+  steps:
+    - name: Setup OCaml
+      uses: ocaml/setup-ocaml@v2
+      with:
+        ocaml-compiler: ${{ inputs.compiler }}
+        opam-disable-sandboxing: true
+        opam-repositories: |
+          default: file://.

.github/install-package/action.yml

@@ -0,0 +1,30 @@
+name: Install Package
+inputs:
+  opam:
+    required: true
+  package:
+    reauired: true
+  env:
+    default: '{}'
+runs:
+  using: composite
+  steps:
+    - name: Get opam cli option
+      id: cli
+      shell: sh
+      run: |
+        if [ "${{ inputs.opam }}" = "opam-2.1" ]; then
+          echo '##[set-output name=cli]--cli=2.1 --confirm-level=unsafe-yes'
+        fi
+    - name: Install ${{ inputs.package }} depopts
+      if: inputs.opam == 'opam-2.0'
+      shell: sh
+      run: |
+        opam depext ${{ inputs.package }}
+    - name: Install ${{ inputs.package }}
+      shell: sh
+      env: ${{ fromJson(inputs.env) }}
+      run: |
+        opam install --deps-only ${{ steps.cli.outputs.cli }} ${{ inputs.package }}
+        opam install ${{ steps.cli.outputs.cli }} ${{ inputs.package }}
+        opam remove ${{ steps.cli.outputs.cli }} ${{ inputs.package }}

.github/install-system-packages/action.yml

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+name: Install System Packages
+inputs:
+  distribution:
+    reauired: true
+runs:
+  using: composite
+  steps:
+    - name: Install debian system packages
+      if: startsWith(inputs.distribution, 'debian') || startsWith(inputs.distribution, 'ubuntu')
+      shell: sh
+      env:
+        DEBIAN_FRONTEND: noninteractive
+      run: |
+        apt-get update
+        apt-get install -qq -yy curl darcs gcc git m4 make mercurial patch rsync sudo unzip bzip2
+    - name: Install alpine system packages
+      if: startsWith(inputs.distribution, 'alpine')
+      shell: sh
+      run: |
+        apk add build-base coreutils curl libgcc libstdc++ musl patch unzip bzip2 mercurial git rsync tar
+    - name: Install yum-based system packages
+      if: startsWith(inputs.distribution, 'centos') || startsWith(inputs.distribution, 'fedora') || startsWith(inputs.distribution, 'oraclelinux')
+      shell: sh
+      run: |
+        yum install -y curl diffutils gcc gcc-c++ tar git m4 make mercurial patch rsync sudo unzip gzip bzip2
+    - name: Install opensuse system packages
+      if: startsWith(inputs.distribution, 'opensuse')
+      shell: sh
+      run: |
+        zypper install -y curl diffutils gcc gcc-c++ tar git m4 make mercurial patch rsync sudo unzip gzip bzip2 which
+    - name: Install archlinux system packages
+      if: startsWith(inputs.distribution, 'archlinux')
+      shell: sh
+      run: |
+        pacman -Sy --noconfirm base-devel unzip git rsync

.github/package-revdeps/action.yml

@@ -0,0 +1,26 @@
+name: Get package revdeps
+inputs:
+  package:
+    reauired: true
+  cache_key:
+    required: true
+runs:
+  using: composite
+  steps:
+    - name: Store package revdeps
+      uses: actions/cache@v2
+      id: cache_revdeps
+      with:
+        path: ${{ inputs.package }}.revdeps
+        key: ${{ inputs.cache_key }}-${{ inputs.package }}
+
+    - name: Get package revdeps
+      id: revdeps
+      shell: sh
+      if: ${{ !steps.cache_revdeps.outputs.cache-hit }}
+      env:
+        OCAMLCLI: ''
+      run: |
+        REVDEPS=`(opam list -s --color=never --depends-on ${{ inputs.package }} --coinstallable-with ${{ inputs.package }} --installable --all-versions --recursive --depopts && opam list -s --color=never --depends-on ${{ inputs.package }} --coinstallable-with ${{ inputs.package }} --installable --all-versions --with-test --depopts) | sort -u | grep -v ${{ inputs.package }} | while read i; do echo "\"$i\""; done | paste -sd ',' -`
+        echo "${{ inputs.package }} revdeps: [$REVDEPS]"
+        echo "[$REVDEPS]" > ${{ inputs.package }}.revdeps

.github/revdeps-config/action.yml

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+name: Get revdeps configl
+inputs:
+  packages:
+    reauired: true
+  cache_key:
+    required: true
+outputs:
+  revdeps_config:
+    description: "Revdeps config"
+    value: ${{ steps.revdeps_config.outputs.result }}
+runs:
+  using: composite
+  steps:
+    - name: Setup node
+      uses: actions/setup-node@v2
+      with:
+        node-version: 14
+    - name: Install @action/cache
+      shell: sh
+      run: npm install @actions/cache
+    - name: Collect revdeps
+      id: revdeps_config
+      uses: actions/github-script@v5
+      with:
+        script: |
+          const cache = require('@actions/cache');
+          const fs = require('fs');
+
+          let config = [];
+          const packages = JSON.parse('${{ inputs.packages }}');
+          await Promise.all(packages.map(async (package) => {
+            await cache.restoreCache([`${package}.revdeps`], `${{ inputs.cache_key }}-${package}`);
+            const revdeps = JSON.parse(fs.readFileSync(`${package}.revdeps`));
+            revdeps.forEach((revdep) => config.push({package, revdep}));
+          }));
+
+          console.log(`Revdeps config: ${JSON.stringify(config, null, 2)}`);
+          return config;

.github/scripts/packages.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+set -e
+
+PACKAGES=`git diff --name-only origin/master..HEAD | grep '^packages' | cut -d'/' -f 3 | while read i; do echo "\"$i\""; done`
+
+echo "Packages to test: [$PACKAGES]"
+echo "##[set-output name=packages][${PACKAGES}]"
+