From 4486da8ef3c270fe318a411ddd0d240ac1fed561 Mon Sep 17 00:00:00 2001
From: Andy Wilkinson <awilkinson@pivotal.io>
Date: Tue, 21 Jan 2020 12:09:17 +0000
Subject: [PATCH] Use JavaExec to invoke Ant with required dependencies on its
 classpath

Previously, we were adding dependencies to Ant's ClassLoader within
Gradle. It is suspected that this was causing sporadic loader
contraint violations as types that Gradle itself uses (from Commons
Compress) were then available from two different ClassLoaders.

This commit reworks the Ant smoke test to use JavaExec and Ant's
launcher to run the build. This allows us to make the necessary
dependencies available to Ant in an isolated manner. The javac
invocation within Ant is now forked to allow it to find the tools jar
even when the build itself is running on a JRE.

Closes gh-19839
---
 .../spring-boot-smoke-test-ant/build.gradle   | 22 +++++++++----------
 .../spring-boot-smoke-test-ant/build.xml      |  2 +-
 2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-ant/build.gradle b/spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-ant/build.gradle
index 8e7b02eb8a..0551df02a2 100644
--- a/spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-ant/build.gradle
+++ b/spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-ant/build.gradle
@@ -25,6 +25,8 @@ plugins.withType(EclipsePlugin) {
 dependencies {
 	antDependencies 'org.apache.ivy:ivy:2.4.0'
 	antDependencies project(path: ':spring-boot-project:spring-boot-tools:spring-boot-antlib')
+	antDependencies 'org.apache.ant:ant-launcher:1.9.3'
+	antDependencies 'org.apache.ant:ant:1.9.3'
 
 	testRepository project(path: ':spring-boot-project:spring-boot-tools:spring-boot-loader', configuration: 'mavenRepository')
 	testRepository project(path: ':spring-boot-project:spring-boot-starters:spring-boot-starter', configuration: 'mavenRepository')
@@ -44,22 +46,18 @@ task syncTestRepository(type: Sync) {
 	}
 }
 
-ant.importBuild('build.xml') {
-	'ant' + it
-}
-ant.properties['ant-spring-boot.version'] = project.version
-ant.properties['projectDir'] = project.layout.projectDirectory
-
-antresolve {
+task antRun(type: JavaExec) {
 	dependsOn syncTestRepository, configurations.antDependencies
-	doFirst {
-		ClassLoader antClassLoader = org.apache.tools.ant.Project.class.classLoader
-		configurations.antDependencies.each { antClassLoader.addURL it.toURI().toURL() }
-	}
+	classpath = configurations.antDependencies;
+	main = 'org.apache.tools.ant.launch.Launcher'
+	systemProperties = [
+		'ant-spring-boot.version' : version,
+		'projectDir': project.layout.projectDirectory
+	]
 }
 
 task test(type: Test) {
-	dependsOn antbuild
+	dependsOn antRun
 	testClassesDirs = sourceSets.test.output.classesDirs
 	classpath = sourceSets.test.runtimeClasspath
 }
diff --git a/spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-ant/build.xml b/spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-ant/build.xml
index 1cc4fcae34..df45ef2f87 100644
--- a/spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-ant/build.xml
+++ b/spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-ant/build.xml
@@ -29,7 +29,7 @@
 	</target>
 
 	<target name="compile" depends="init" description="compile">
-		<javac srcdir="src/main/java" destdir="build/ant/classes" classpathref="compile.classpath" />
+		<javac srcdir="src/main/java" destdir="build/ant/classes" classpathref="compile.classpath" fork="true" />
 	</target>
 
 	<target name="clean" description="cleans all created files/dirs">