From 27a9b822e59388e76380fc4dec25c03e6d229f79 Mon Sep 17 00:00:00 2001
From: Leonid Bushuev <leonid.bushuev@jetbrains.com>
Date: Fri, 15 Feb 2019 18:43:24 +0100
Subject: [PATCH] Any compatibility error message (related to IDEA-207341)

---
 .../intellij/rt/ant/execution/AntMain2.java   | 43 +++++++++++++------
 1 file changed, 29 insertions(+), 14 deletions(-)

diff --git a/java/java-runtime/src/com/intellij/rt/ant/execution/AntMain2.java b/java/java-runtime/src/com/intellij/rt/ant/execution/AntMain2.java
index dc072a08b7c9..939e6749e7fb 100644
--- a/java/java-runtime/src/com/intellij/rt/ant/execution/AntMain2.java
+++ b/java/java-runtime/src/com/intellij/rt/ant/execution/AntMain2.java
@@ -20,24 +20,39 @@ import java.lang.reflect.InvocationTargetException;
 public final class AntMain2 {
 
   public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, IllegalAccessException, InvocationTargetException {
-    IdeaAntLogger2.guardStreams();
     
-    // as we build classpath ourselves, and ensure all libraries are added to classpath, 
-    // preferred way for us to run ant will be using the traditional ant entry point, via the "Main" class 
     try {
-      final Class antMain = Class.forName("org.apache.tools.ant.Main");
-      antMain.getMethod("main", new Class[]{args.getClass()}).invoke(null, new Object[]{args});
-      return;
+      IdeaAntLogger2.guardStreams();
+
+      // as we build classpath ourselves, and ensure all libraries are added to classpath, 
+      // preferred way for us to run ant will be using the traditional ant entry point, via the "Main" class 
+      try {
+        final Class antMain = Class.forName("org.apache.tools.ant.Main");
+        antMain.getMethod("main", new Class[]{args.getClass()}).invoke(null, new Object[]{args});
+        return;
+      }
+      catch (ClassNotFoundException e) {
+        // ignore
+      }
+
+      // fallback: try the newer approach, launcher
+      // This approach is less preferred in our case, but still...
+      // From the ant documentation: "You should start the launcher with the most minimal classpath possible, generally just the ant-launcher.jar."
+      final Class antLauncher = Class.forName("org.apache.tools.ant.launch.Launcher");
+      antLauncher.getMethod("main", new Class[]{args.getClass()}).invoke(null, new Object[]{args});
     }
-    catch (ClassNotFoundException e) {
-      // ignore
+    catch (UnsupportedClassVersionError ucv) {
+      String jreVersion = System.getProperty("java.version");
+      String message = "\nThe version of the executed Ant is not compatible with the JRE version " + jreVersion + ". " +
+                       "\nTo use Ant with this Java version, download an older version of Ant, " +
+                       "unpack it and specify the path to it on the 'Execution' tab in the 'Build File Properties' dialog " +
+                       "(accessible via the 'Ant Build' tool window -> Properties button).";
+      throw new IllegalStateException(message) {
+        public synchronized Throwable fillInStackTrace() {
+          return this; 
+        }
+      };
     }
-    
-    // fallback: try the newer approach, launcher
-    // This approach is less preferred in our case, but still...
-    // From the ant documentation: "You should start the launcher with the most minimal classpath possible, generally just the ant-launcher.jar."
-    final Class antLauncher = Class.forName("org.apache.tools.ant.launch.Launcher");
-    antLauncher.getMethod("main", new Class[]{args.getClass()}).invoke(null, new Object[]{args});
 
   }
 }