provide flag ReportUsedMetadataFiles to print all parsed metadata files

Author: wirthi

substratevm/src/com.oracle.svm.configure/src/com/oracle/svm/configure/ConfigurationParser.java

@@ -83,6 +83,7 @@ public static InputStream openStream(URI uri) throws IOException {
     public static final String BUNDLE_KEY = "bundle";
     private final EconomicMap<String, EconomicSet<String>> seenUnknownAttributesByType = EconomicMap.create();
     private final EnumSet<ConfigurationParserOption> parserOptions;
+    private static EconomicSet<String> usedMetadataFiles = EconomicSet.create();
 
     protected ConfigurationParser(EnumSet<ConfigurationParserOption> parserOptions) {
         this.parserOptions = parserOptions;
@@ -106,6 +107,7 @@ protected final boolean checkOption(ConfigurationParserOption option) {
     public void parseAndRegister(URI uri) throws IOException {
         try (Reader reader = openReader(uri)) {
             parseAndRegister(new JsonParser(reader).parse(), uri);
+            reportUsedMetadataFile(uri); // report if successfully parsed
         } catch (FileNotFoundException e) {
             /*
              * Ignore: *-config.json files can be missing when reachability-metadata.json is
@@ -114,6 +116,23 @@ public void parseAndRegister(URI uri) throws IOException {
         }
     }
 
+    private static void reportUsedMetadataFile(URI uri) {
+        // usedMetadataFiles should not be null in regular usecases, unless already read
+        // OmitPreviousConfigTests is an example where this unfortunately happens.
+        if (usedMetadataFiles != null) {
+            usedMetadataFiles.add(uri.toString());
+        }
+    }
+
+    public static EconomicSet<String> getUsedMetadataFiles() {
+        if (usedMetadataFiles == null) {
+            return null;
+        }
+        EconomicSet<String> set = usedMetadataFiles;
+        usedMetadataFiles = null; // avoid retaining memory here
+        return set;
+    }
+
     protected static BufferedReader openReader(URI uri) throws IOException {
         return new BufferedReader(new InputStreamReader(openStream(uri)));
     }

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/SubstrateOptions.java

@@ -1392,6 +1392,9 @@ protected void onValueUpdate(EconomicMap<OptionKey<?>, Object> values, String ol
     @Option(help = "Enable runtime instantiation of reflection objects for non-invoked methods.", type = OptionType.Expert, deprecated = true)//
     public static final HostedOptionKey<Boolean> ConfigureReflectionMetadata = new HostedOptionKey<>(true);
 
+    @Option(help = "Print a list of parsed metadata configuration files.", type = OptionType.Expert)//
+    public static final HostedOptionKey<Boolean> ReportUsedMetadataFiles = new HostedOptionKey<>(false);
+
     @Option(help = "Include a list of methods included in the image for runtime inspection.", type = OptionType.Expert)//
     public static final HostedOptionKey<Boolean> IncludeMethodData = new HostedOptionKey<>(false);
 

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/ReportUsedMetadataFilesFeature.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2026, 2026, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.svm.hosted;
+
+import com.oracle.graal.pointsto.reports.ReportUtils;
+import com.oracle.svm.configure.ConfigurationParser;
+import com.oracle.svm.core.SubstrateOptions;
+import com.oracle.svm.core.feature.AutomaticallyRegisteredFeature;
+import com.oracle.svm.core.feature.InternalFeature;
+import org.graalvm.collections.EconomicSet;
+
+import java.io.File;
+import java.io.PrintWriter;
+import java.util.Collections;
+import java.util.List;
+
+@AutomaticallyRegisteredFeature
+public class ReportUsedMetadataFilesFeature implements InternalFeature {
+
+    private EconomicSet<String> usedMetadataFiles;
+    private boolean completed = false;
+
+    @Override
+    public void duringAnalysis(DuringAnalysisAccess access) {
+        // get the set in any case to clean up memory in the parser
+        usedMetadataFiles = ConfigurationParser.getUsedMetadataFiles();
+        if (SubstrateOptions.ReportUsedMetadataFiles.getValue() && !completed) {
+            File file = ReportUtils.reportFile(SubstrateOptions.reportsPath(), "usedMetadataFiles", "txt");
+            ReportUtils.report("usedMetadataFiles", file.toPath(), this::printMetadataFiles);
+        }
+    }
+
+    private void printMetadataFiles(PrintWriter out) {
+        if (usedMetadataFiles != null) {
+            List<String> files = usedMetadataFiles.toList();
+            Collections.sort(files);
+            for (String file : files) {
+                out.println("used metadata: " + file);
+            }
+        } else {
+            out.println("no metadata file used");
+        }
+        completed = true;
+    }
+}