From 73dff99b72b03834ddc8c68eb17d449be52f3405 Mon Sep 17 00:00:00 2001
From: Thor Rognan <thor.rognan@gmail.com>
Date: Sat, 17 Sep 2022 12:56:17 +0200
Subject: [PATCH] Bump JDK running Gradle from 11 to 17

This commit decouples the JDK running Gradle from the one building the
project.

Gradle will by default use the same JDK for building the project as it
does for running Gradle. Newer JDKs are assumed to be more performant,
contain fewer bugs and to come with desirable features that we would
like to utilize in our build, but doing so should not endanger
backwards compatibility for the plugin itself. We can do that now by
utilizing Gradle toolchains, which allows us to use one JDK/JRE for
running Gradle and the other for building the project, i.e. executing
`javac`.

Doing this requires us to make multiple JDKs available to the Gradle
build action for each individual execution of the build. The setup-java
action doesn't support this at the moment, and the multiple build steps
configured for actions/setup-java in this commit is at best a
workaround for this, and at worst a bad assumption with respect to
environment variables or other settings being overwritten. Furthermore,
there's no handling of duplicate invocations of the action.

Hopefully both actions/setup-java and gradle/gradle-build-action will
handle all of this gracefully.

For more details, see:
- https://github.com/actions/setup-java/issues/44
- https://github.com/gradle/gradle/issues/14903
---
 .github/workflows/main.yml | 33 ++++++++++++++++++++++++---------
 plugin/build.gradle.kts    | 13 +++++++++++++
 2 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index f35002c..3177964 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -10,30 +10,45 @@ jobs:
     strategy:
       matrix:
         include:
-          - { os: 'macos-latest', arch: 'x64', java-version: '11', gradle-version: '7.3' }
-          - { os: 'ubuntu-latest', arch: 'x64', java-version: '11', gradle-version: '7.3' }
-          - { os: 'windows-latest', arch: 'x64', java-version: '11', gradle-version: '7.3' }
-    name: Gradle ${{ matrix.gradle-version }}, Java ${{ matrix.java-version }} on ${{ matrix.os }} (${{ matrix.arch }})
+          - { os: 'macos-latest', arch: 'x64', toolchain-jdk: '11', gradle-jdk: '17', gradle-version: '7.3' }
+          - { os: 'ubuntu-latest', arch: 'x64', toolchain-jdk: '11', gradle-jdk: '17', gradle-version: '7.3' }
+          - { os: 'windows-latest', arch: 'x64', toolchain-jdk: '11', gradle-jdk: '17', gradle-version: '7.3' }
+    name: >
+      Gradle ${{ matrix.gradle-version }} w/JDK ${{ matrix.gradle-jdk }}
+      on ${{ matrix.os }} (${{ matrix.arch }}) and toolchain JDK ${{ matrix.toolchain-jdk}}
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v2
-      - name: Configure JDK ${{ matrix.java-version }} (${{ matrix.arch }})
+      - name: Configure JDK ${{ matrix.gradle-jdk }} (${{ matrix.arch }})
+        id: configure-gradle-jdk
         uses: actions/setup-java@v2
         with:
           architecture: ${{ matrix.arch }}
           distribution: 'temurin'
-          java-version: ${{ matrix.java-version }}
-      - uses: gradle/gradle-build-action@v2
+          java-version: ${{ matrix.gradle-jdk }}
+      - name: Configure JDK ${{ matrix.toolchain-jdk }} (${{ matrix.arch }})
+        id: configure-toolchain-jdk
+        uses: actions/setup-java@v2
+        with:
+          architecture: ${{ matrix.arch }}
+          distribution: 'temurin'
+          java-version: ${{ matrix.toolchain-jdk }}
+      - name: Build project
+        uses: gradle/gradle-build-action@v2
         with:
           # Only write to the cache on the 'main' branch
           cache-read-only: ${{ github.ref != 'refs/heads/main' }}
           gradle-version: ${{ matrix.gradle-version }}
-          arguments: build --scan
+          arguments: >
+            build --scan
+            -Dorg.gradle.java.installations.auto-detect=false
+            -Dorg.gradle.java.installations.auto-download=false
+            -Dorg.gradle.java.installations.paths=${{ steps.configure-gradle-jdk.outputs.path }},${{ steps.configure-toolchain-jdk.outputs.path }}
       - name: Upload build reports
         uses: actions/upload-artifact@v2
         if: always()
         with:
-          name: build-reports-${{ matrix.os }}-${{ matrix.arch }}-jdk-${{ matrix.java-version }}
+          name: build-reports-${{ matrix.os }}-${{ matrix.arch }}-gradle-jdk-${{ matrix.gradle-jdk }}-toolchain-jdk-${{ matrix.toolchain-jdk }}
           path: |
             build/reports
             ./**/build/reports
diff --git a/plugin/build.gradle.kts b/plugin/build.gradle.kts
index f791b5f..7b043b8 100644
--- a/plugin/build.gradle.kts
+++ b/plugin/build.gradle.kts
@@ -11,6 +11,7 @@ plugins {
   id("org.jlleitschuh.gradle.ktlint") version "10.2.0"
 }
 
+val jdkVersion: JavaLanguageVersion = JavaLanguageVersion.of(11)
 val functionalTestSourceSet: SourceSet = sourceSets.create("functionalTest")
 configurations["functionalTestImplementation"].extendsFrom(configurations["testImplementation"])
 
@@ -30,6 +31,18 @@ gradlePlugin {
   }
 }
 
+java {
+  toolchain {
+    languageVersion.set(jdkVersion)
+  }
+}
+
+kotlin {
+  jvmToolchain {
+    (this as JavaToolchainSpec).languageVersion.set(jdkVersion)
+  }
+}
+
 tasks.withType<JavaCompile>().configureEach {
   options.release.set(8)
 }