Dist: dump the base CDS archive when the copied JDK has none (fixes master on macOS x64)

AGENTS.md

@@ -157,11 +157,15 @@ This repository has multiple entry points that may trigger compilation/build beh
 wurst4vscode starts the server with `-XX:+AutoCreateSharedArchive`: the JVM writes an AppCDS archive next to the
 compiler jar when the first session ends, and the sessions after it start from it. That archive sits on the
 runtime's own base archive, which `deploy.gradle` makes (`jlink --generate-cds-archive`; macOS copies a full JDK, which
-has one) and `assembleSlimCompilerDist` checks for. Without it the JVM silently runs without any archive, which is
-how the earlier attempt went unnoticed. jlink writes the archive with a JVM of its own, which takes on the options it is started with: the
-CI exports `JAVA_TOOL_OPTIONS=-XX:+UseCompactObjectHeaders`, so `deploy.gradle` removes it (and the other JVM option variables) for that
-step, or only `classes_coh.jsa` is made, which a runtime started without that option cannot use. The extension passes `-Xlog:disable` because the JVM reports archive trouble
-on stdout, which is the protocol stream: never print anything of your own there.
+usually has one, and `assembleSlimCompilerDist` dumps one with `java -Xshare:dump` when the JDK has none: the Temurin
+for macOS x64 on CI does not). `assembleSlimCompilerDist` then starts the runtime with `-Xshare:on`, which fails when
+there is no usable archive. Without one the JVM silently runs without any, which is how the earlier attempt went
+unnoticed. A base archive is written by a JVM which takes on the options it is started with: the CI exports
+`JAVA_TOOL_OPTIONS=-XX:+UseCompactObjectHeaders`, so `deploy.gradle` removes it (and the other JVM option variables) for
+the JVMs it starts, or only `classes_coh.jsa` is made, which a runtime started without that option cannot use. Pull-request
+CI packages nothing (only pushes to master do, on every host), so a change here is not tested on macOS before it merges.
+The extension passes `-Xlog:disable` because the JVM reports archive trouble on stdout, which is the protocol stream:
+never print anything of your own there.
 
 ### Build-map pipeline (centralized)
 

de.peeeq.wurstscript/deploy.gradle

@@ -59,6 +59,7 @@ def jdepsPathProvider = javaHomeProvider.map { home ->
 def jlinkPathProvider = javaHomeProvider.map { home ->
     new File(home, "bin/jlink${os.isWindows() ? '.exe' : ''}").absolutePath
 }
+def javaExecutableName = os.isWindows() ? "java.exe" : "java"
 def jmodsDirProvider = javaHomeProvider.map { home ->
     new File(home, "jmods").absolutePath
 }
@@ -97,6 +98,27 @@ abstract class JdepsRawTask extends DefaultTask {
     }
 }
 
+/**
+ * Runs the java of a runtime image without the JVM option variables of the build machine: CI exports JAVA_TOOL_OPTIONS
+ * for its tests, and a base class data sharing archive takes on the options of the JVM which writes it (compact
+ * object headers make it classes_coh.jsa, which a JVM started without them cannot use).
+ */
+class RuntimeJava {
+    static String run(File java, List<String> options) {
+        def command = [java.absolutePath] + options
+        def pb = new ProcessBuilder(command)
+        pb.redirectErrorStream(true)
+        ["JAVA_TOOL_OPTIONS", "_JAVA_OPTIONS", "JDK_JAVA_OPTIONS"].each { pb.environment().remove(it) }
+        def process = pb.start()
+        def output = process.inputStream.getText("UTF-8")
+        def exit = process.waitFor()
+        if (exit != 0) {
+            throw new org.gradle.api.GradleException("`" + command.join(" ") + "` exited with " + exit + ": " + output)
+        }
+        return output
+    }
+}
+
 def fatJarProvider = tasks.named("shadowJar").flatMap { it.archiveFile } // Provider<RegularFile>
 
 tasks.register("jdepsRaw", JdepsRawTask) {
@@ -228,10 +250,16 @@ tasks.register("assembleSlimCompilerDist", Copy) {
     doLast {
         logger.lifecycle("[dist] Folder ready at: ${distRoot.get().asFile}")
         def runtime = new File(distRoot.get().asFile, "wurst-runtime")
+        def java = new File(runtime, "bin/" + javaExecutableName)
+        // jlink made the archive of the slim runtime, and a full JDK (macOS) normally brings its own, but not every
+        // build does: the Temurin for macOS x64 on CI has none. -Xshare:dump writes it next to the JVM library.
         if (!["bin/server/classes.jsa", "lib/server/classes.jsa"].any { new File(runtime, it).exists() }) {
-            throw new GradleException("The runtime has no base CDS archive (classes.jsa under bin/server or lib/server), " +
-                    "so the language server cannot start from an AppCDS archive.")
+            logger.lifecycle("[dist] The runtime has no base CDS archive, dumping it")
+            RuntimeJava.run(java, ["-Xshare:dump"])
         }
+        // -Xshare:on makes the JVM fail when it has no usable base archive, where it would otherwise run without one
+        // and nobody would notice
+        RuntimeJava.run(java, ["-Xshare:on", "-version"])
     }
 }