Support building Dafny from source

.github/workflows/main.yml

@@ -15,13 +15,14 @@ jobs:
       fail-fast: false
       matrix:
         os: [macos-latest, ubuntu-latest, windows-latest]
-        dafny: [3.0.0, 3.8.1, 3.13.1, 4.0.0, nightly-2023-02-28-80a0e49, nightly-latest]
-        # Windows 2.3.0 requires mono
+        dafny: [3.8.1, 3.13.1, 4.0.0, 4.9.1, nightly-2023-02-28-80a0e49, nightly-latest]
         include:
-          - os: macos-latest
-            dafny: 2.3.0
-          - os: ubuntu-latest
-            dafny: 2.3.0
+          # Test building from source from a subset of versions
+          - dafny: 4.0.0
+            build-from-source: v4.0.0
+          - dafny: 4.9.0
+            build-from-source: v4.9.0
+
     steps:
       # The first call to `dotnet tool` on a fresh runner sometimes takes multiple minutes,
       # perhaps because it is lazily downloading and installing assets.
@@ -36,6 +37,7 @@ jobs:
         uses: ./
         with:
           dafny-version: ${{ matrix.dafny }}
+          build-from-source: ${{ matrix.build-from-source }}
 
       - name: verify dafny
         shell: bash

README.md

@@ -16,7 +16,7 @@ If you need to use a specific version:
 - name: "Install Dafny"
   uses: dafny-lang/setup-dafny-action@v1
   with:
-    dafny-version: "2.3.0"
+    dafny-version: "4.9.1"
 ```
 
 You can also use `nightly-latest` to install the most recent nightly pre-release.
@@ -26,3 +26,21 @@ containing the actual resolved Dafny version: particularly useful for `nightly-l
 
 This action transparently works on macOS by detecting the running OS. You can
 just set `runs-on` to a macOS virtual environment like `macos-latest`.
+
+You can also build Dafny from source,
+if you want to run against a branch of Dafny still in development:
+
+```yml
+- name: "Install Dafny"
+  uses: dafny-lang/setup-dafny-action@v1
+  with:
+    dafny-version: "4.9.1"
+    build-from-source: support-puppies-and-rainbows
+
+```
+
+`build-from-source` can be set to a branch name, tag, commit sha,
+and so on: anything that `actions/checkout` understands.
+Note that `dafny-version` is still currently required
+in order to still set the `DAFNY_VERSION` environment variable,
+as it is not automatically extracted from the built Dafny.

action.yml

@@ -8,16 +8,33 @@ inputs:
     description: "Dafny version to install"
     required: true
     default: "3.1.0"
+  build-from-source:
+    description: "dafny-lang/dafny commit-ish to build"
+    required: false
 runs:
   using: "composite"
   steps:
+
   - uses: actions/setup-dotnet@v4
     with:
       dotnet-version: '6.0.x'
-  - uses: actions/setup-node@v4
+
+  - if: ${{ !inputs.build-from-source }}
+    uses: actions/setup-node@v4
     with:
       node-version: 16
-  - run: node $GITHUB_ACTION_PATH/dist/index.js
+  - if: ${{ !inputs.build-from-source }}
+    run: node $GITHUB_ACTION_PATH/dist/index.js
     shell: bash
     env:
       INPUT_DAFNY-VERSION: ${{ inputs.dafny-version }}
+
+  - if: ${{ inputs.build-from-source }}
+    uses: actions/setup-dotnet@v4
+    with:
+      dotnet-version: '8.0.x'
+  - if: ${{ inputs.build-from-source }}
+    uses: ./build_dafny_from_source
+    with:
+      dafny-version: ${{ inputs.dafny-version }}
+      ref: ${{ inputs.build-from-source }}

build_dafny_from_source/action.yml

@@ -0,0 +1,56 @@
+name: "Build Dafny from source"
+description: "Builds the given branch of Dafny from source"
+inputs:
+  dafny-version:
+    description: "Dafny version to build from source"
+    required: true
+    type: string
+  ref:
+    description: "The Dafny branch, tag or SHA to build"
+    required: true
+    type: string
+runs:
+  using: "composite"
+  steps:
+    - uses: actions/setup-java@v3
+      with:
+        distribution: "corretto"
+        java-version: "17"
+
+    - name: Checkout Dafny
+      uses: actions/checkout@v4
+      with:
+        repository: dafny-lang/dafny
+        path: dafny
+        ref: ${{ inputs.ref }}
+
+    - name: Setup Z3
+      uses: cda-tum/[email protected]
+      with:
+        version: 4.12.1
+
+    - name: Build Dafny
+      shell: bash
+      run: |
+        make -C dafny exe
+
+    - name: Add dafny to PATH (non-Windows)
+      if: runner.os != 'Windows'
+      shell: bash
+      run: |
+        echo ${{ github.workspace }}/dafny/Scripts >> $GITHUB_PATH
+    - name: Add dafny to PATH (Windows)
+      if: runner.os == 'Windows'
+      shell: pwsh
+      run: |
+        Add-Content $env:GITHUB_PATH "${{ github.workspace }}/dafny/Scripts"
+
+    - name: Export DAFNY_VERSION
+      shell: bash
+      run: |
+        echo "DAFNY_VERSION=${{ inputs.dafny-version }}" >> $GITHUB_ENV
+
+    - name: Install reportgenerator
+      shell: bash
+      run: |
+        dotnet tool install -g dafny-reportgenerator --version 1.*