8344708: Implement JEP 511: Module Import Declarations

src/java.base/share/classes/jdk/internal/javac/PreviewFeature.java

@@ -76,8 +76,7 @@ public enum Feature {
         STRUCTURED_CONCURRENCY,
         CLASSFILE_API,
         STREAM_GATHERERS,
-        @JEP(number=494, title="Module Import Declarations", status="Second Preview")
-        MODULE_IMPORTS,
+        MODULE_IMPORTS, //remove when the boot JDK is JDK 25
         @JEP(number=478, title="Key Derivation Function API", status="Preview")
         KEY_DERIVATION,
         LANGUAGE_MODEL,

src/java.base/share/classes/jdk/internal/module/ModuleInfo.java

@@ -408,24 +408,10 @@ private Builder readModuleAttribute(DataInput in, ConstantPool cpool, int major,
                     throw invalidModuleDescriptor("The requires entry for java.base"
                                                   + " has ACC_SYNTHETIC set");
                 }
-                // requires transitive java.base is illegal unless:
-                // - the major version is 53 (JDK 9), or:
-                // - the classfile is a preview classfile, or:
-                // - the module is deemed to be participating in preview
-                //   (i.e. the module is a java.* module)
-                // requires static java.base is illegal unless:
-                // - the major version is 53 (JDK 9), or:
-                if (major >= 54
-                    && ((mods.contains(Requires.Modifier.TRANSITIVE)
-                         && !isPreview
-                         && !"java.se".equals(mn))
-                        || mods.contains(Requires.Modifier.STATIC))) {
-                    String flagName;
-                    if (mods.contains(Requires.Modifier.STATIC)) {
-                        flagName = "ACC_STATIC_PHASE";
-                    } else {
-                        flagName = "ACC_TRANSITIVE";
-                    }
+                // requires static java.base is illegal unless
+                // the major version is 53 (JDK 9)
+                if (major >= 54 && mods.contains(Requires.Modifier.STATIC)) {
+                    String flagName = "ACC_STATIC_PHASE";
                     throw invalidModuleDescriptor("The requires entry for java.base"
                                                   + " has " + flagName + " set");
                 }

src/jdk.compiler/share/classes/com/sun/source/tree/ImportTree.java

@@ -25,8 +25,6 @@
 
 package com.sun.source.tree;
 
-import jdk.internal.javac.PreviewFeature;
-
 /**
  * A tree node for an import declaration.
  *
@@ -49,11 +47,11 @@ public interface ImportTree extends Tree {
      * @return true if this is a static import
      */
     boolean isStatic();
+
     /**
      * {@return true if this is an module import declaration.}
-     * @since 23
+     * @since 25
      */
-    @PreviewFeature(feature=PreviewFeature.Feature.MODULE_IMPORTS, reflective=true)
     boolean isModule();
 
     /**

src/jdk.compiler/share/classes/com/sun/tools/javac/code/Preview.java

@@ -153,9 +153,7 @@ public boolean participatesInPreview(Symtab syms, ModuleSymbol m) {
         // s participates in the preview API
         return syms.java_base.exports.stream()
                 .filter(ed -> ed.packge.fullname == names.jdk_internal_javac)
-                .anyMatch(ed -> ed.modules.contains(m)) ||
-               //the specification lists the java.se module as participating in preview:
-               m.name == names.java_se;
+                .anyMatch(ed -> ed.modules.contains(m));
     }
 
     /**
@@ -231,8 +229,6 @@ public boolean isPreview(Feature feature) {
             case IMPLICIT_CLASSES -> true;
             case FLEXIBLE_CONSTRUCTORS -> true;
             case PRIMITIVE_PATTERNS -> true;
-            case MODULE_IMPORTS -> true;
-            case JAVA_BASE_TRANSITIVE -> true;
             //Note: this is a backdoor which allows to optionally treat all features as 'preview' (for testing).
             //When real preview features will be added, this method can be implemented to return 'true'
             //for those selected features, and 'false' for all the others.

src/jdk.compiler/share/classes/com/sun/tools/javac/code/Source.java

@@ -267,8 +267,8 @@ public enum Feature {
         UNNAMED_VARIABLES(JDK22, Fragments.FeatureUnnamedVariables, DiagKind.PLURAL),
         PRIMITIVE_PATTERNS(JDK23, Fragments.FeaturePrimitivePatterns, DiagKind.PLURAL),
         FLEXIBLE_CONSTRUCTORS(JDK22, Fragments.FeatureFlexibleConstructors, DiagKind.NORMAL),
-        MODULE_IMPORTS(JDK23, Fragments.FeatureModuleImports, DiagKind.PLURAL),
-        JAVA_BASE_TRANSITIVE(JDK24, Fragments.FeatureJavaBaseTransitive, DiagKind.PLURAL),
+        MODULE_IMPORTS(JDK25, Fragments.FeatureModuleImports, DiagKind.PLURAL),
+        JAVA_BASE_TRANSITIVE(JDK25, Fragments.FeatureJavaBaseTransitive, DiagKind.PLURAL),
         PRIVATE_MEMBERS_IN_PERMITS_CLAUSE(JDK19),
         ERASE_POLY_SIG_RETURN_TYPE(JDK24),
         ;

src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/ClassReader.java

@@ -1202,11 +1202,6 @@ protected void read(Symbol sym, int attrLen) {
                             ModuleSymbol rsym = poolReader.getModule(nextChar());
                             Set<RequiresFlag> flags = readRequiresFlags(nextChar());
                             if (rsym == syms.java_base && majorVersion >= V54.major) {
-                                if (flags.contains(RequiresFlag.TRANSITIVE) &&
-                                    (majorVersion != Version.MAX().major || !previewClassFile) &&
-                                    !preview.participatesInPreview(syms, msym)) {
-                                    throw badClassFile("bad.requires.flag", RequiresFlag.TRANSITIVE);
-                                }
                                 if (flags.contains(RequiresFlag.STATIC_PHASE)) {
                                     throw badClassFile("bad.requires.flag", RequiresFlag.STATIC_PHASE);
                                 }

src/jdk.jshell/share/classes/jdk/internal/jshell/tool/JShellTool.java

@@ -131,6 +131,7 @@
 import static jdk.jshell.Snippet.SubKind.TEMP_VAR_EXPRESSION_SUBKIND;
 import static jdk.jshell.Snippet.SubKind.VAR_VALUE_SUBKIND;
 import static java.util.stream.Collectors.toMap;
+import javax.lang.model.SourceVersion;
 import static jdk.internal.jshell.debug.InternalDebugControl.DBG_COMPA;
 import static jdk.internal.jshell.debug.InternalDebugControl.DBG_DEP;
 import static jdk.internal.jshell.debug.InternalDebugControl.DBG_EVNT;
@@ -642,7 +643,10 @@ Options parse(OptionSet options) {
             } else {
                 String packedStartup = prefs.get(STARTUP_KEY);
                 boolean preview = previewEnabled(options);
-                initialStartup = Startup.unpack(packedStartup, preview, new InitMessageHandler());
+                String sourceLevel = detectSourceLevel(options.valuesOf(argC)
+                                                              .toArray(String[]::new));
+                initialStartup = Startup.unpack(packedStartup, sourceLevel,
+                                                preview, new InitMessageHandler());
             }
             if (options.has(argExecution)) {
                 executionControlSpec = options.valueOf(argExecution);
@@ -2311,7 +2315,8 @@ boolean setStart(ArgTokenizer at) {
             }
         } else if (defaultOption) {
             boolean preview = options.hasOption(OptionKind.ENABLE_PREVIEW);
-            startup = Startup.defaultStartup(preview, this);
+            String sourceLevel = detectSourceLevel(options.compilerOptions());
+            startup = Startup.defaultStartup(sourceLevel, preview, this);
         } else if (noneOption) {
             startup = Startup.noStartup();
         }
@@ -2329,7 +2334,8 @@ void showSetStart() {
         String retained = prefs.get(STARTUP_KEY);
         if (retained != null) {
             boolean preview = options.hasOption(OptionKind.ENABLE_PREVIEW);
-            Startup retainedStart = Startup.unpack(retained, preview, this);
+            String sourceLevel = detectSourceLevel(options.compilerOptions());
+            Startup retainedStart = Startup.unpack(retained, sourceLevel, preview, this);
             boolean currentDifferent = !startup.equals(retainedStart);
             sb.append(retainedStart.show(true));
             if (currentDifferent) {
@@ -2346,6 +2352,19 @@ void showSetStart() {
         hard(escape(sb));
     }
 
+    private String detectSourceLevel(String[] compilerOptions) {
+        for (int i = 0; i < compilerOptions.length; i++) {
+            switch (compilerOptions[i]) {
+                case "-source", "--source", "--release":
+                    if (i + 1 < compilerOptions.length) {
+                        return compilerOptions[i + 1];
+                    }
+            }
+        }
+
+        return Integer.toString(SourceVersion.latest().runtimeVersion().feature());
+    }
+
     private void showIndent() {
         hard("/set indent %s", indent());
     }

src/jdk.jshell/share/classes/jdk/internal/jshell/tool/Startup.java

@@ -25,15 +25,20 @@
 
 package jdk.internal.jshell.tool;
 
+import com.sun.tools.javac.code.Source;
+import com.sun.tools.javac.code.Source.Feature;
 import java.nio.file.AccessDeniedException;
 import java.nio.file.Files;
 import java.nio.file.NoSuchFileException;
 import java.time.LocalDateTime;
 import java.time.format.DateTimeFormatter;
 import java.time.format.FormatStyle;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
+import java.util.EnumMap;
 import java.util.List;
+import java.util.Map;
 import java.util.Objects;
 import static java.util.stream.Collectors.joining;
 import static jdk.internal.jshell.tool.JShellTool.RECORD_SEPARATOR;
@@ -118,13 +123,10 @@ public boolean equals(Object o) {
     }
 
     private static final String DEFAULT_STARTUP_NAME = "DEFAULT";
-    private static final String PREVIEW_DEFAULT_STARTUP_NAME = "PREVIEW_DEFAULT";
 
     // cached DEFAULT start-up
-    private static Startup[] defaultStartup = new Startup[] {
-        null, //standard startup
-        null  //preview  startup
-    };
+    private static Map<DefaultStartupType, Startup> defaultStartup =
+            new EnumMap<>(DefaultStartupType.class);
 
     // the list of entries
     private List<StartupEntry> entries;
@@ -170,8 +172,10 @@ boolean isEmpty() {
     boolean isDefault() {
         if (entries.size() == 1) {
             StartupEntry sue = entries.get(0);
-            if (sue.isBuiltIn && (sue.name.equals(DEFAULT_STARTUP_NAME) ||
-                                  sue.name.equals(PREVIEW_DEFAULT_STARTUP_NAME))) {
+            if (sue.isBuiltIn &&
+                Arrays.stream(DefaultStartupType.values())
+                      .map(DefaultStartupType::getResourceName)
+                      .anyMatch(sue.name::equals)) {
                 return true;
             }
         }
@@ -222,7 +226,7 @@ String showDetail() {
      * @param mh handler for error messages
      * @return Startup, or default startup when error (message has been printed)
      */
-    static Startup unpack(String storedForm, boolean preview, MessageHandler mh) {
+    static Startup unpack(String storedForm, String sourceLevel, boolean preview, MessageHandler mh) {
         if (storedForm != null) {
             if (storedForm.isEmpty()) {
                 return noStartup();
@@ -243,14 +247,18 @@ static Startup unpack(String storedForm, boolean preview, MessageHandler mh) {
                         String name = all[i + 1];
                         String timeStamp = all[i + 2];
                         String content = all[i + 3];
-                        if (isBuiltIn) {
-                            // update to current definition, use stored if removed/error
-                            String resource = getResource(name);
-                            if (resource != null) {
-                                content = resource;
+                        if (isBuiltIn && DEFAULT_STARTUP_NAME.equals(name)) {
+                            e.addAll(defaultStartup(sourceLevel, preview, mh).entries);
+                        } else {
+                            if (isBuiltIn) {
+                                // update to current definition, use stored if removed/error
+                                String resource = getResource(name);
+                                if (resource != null) {
+                                    content = resource;
+                                }
                             }
+                            e.add(new StartupEntry(isBuiltIn, name, content, timeStamp));
                         }
-                        e.add(new StartupEntry(isBuiltIn, name, content, timeStamp));
                     }
                     return new Startup(e);
                 } else {
@@ -260,7 +268,7 @@ static Startup unpack(String storedForm, boolean preview, MessageHandler mh) {
                 mh.errormsg("jshell.err.corrupted.stored.startup", ex.getMessage());
             }
         }
-        return defaultStartup(preview, mh);
+        return defaultStartup(sourceLevel, preview, mh);
     }
 
     /**
@@ -329,26 +337,49 @@ static Startup noStartup() {
      * @param mh handler for error messages
      * @return The default Startup, or empty startup when error (message has been printed)
      */
-    static Startup defaultStartup(boolean preview, MessageHandler mh) {
-        int idx = preview ? 1 : 0;
+    static Startup defaultStartup(String sourceLevel, boolean preview, MessageHandler mh) {
+        Source source = Source.lookup(sourceLevel);
+        DefaultStartupType type;
+        if (preview) {
+            type = DefaultStartupType.PREVIEW_DEFAULT_STARTUP;
+        } else if (source == null ||
+                   Feature.MODULE_IMPORTS.allowedInSource(source)) {
+            type = DefaultStartupType.DEFAULT_STARTUP;
+        } else {
+            type = DefaultStartupType.DEFAULT_STARTUP_NO_MODULE_IMPORTS;
+        }
+
+        return defaultStartup.computeIfAbsent(type, t -> {
+            String resourceName = t.getResourceName();
+
+            try {
+                String content = readResource(resourceName);
+                return new Startup(
+                        new StartupEntry(true, DEFAULT_STARTUP_NAME, content));
+            } catch (AccessDeniedException e) {
+                mh.errormsg("jshell.err.file.not.accessible", "jshell", resourceName, e.getMessage());
+            } catch (NoSuchFileException e) {
+                mh.errormsg("jshell.err.file.not.found", "jshell", resourceName);
+            } catch (Exception e) {
+                mh.errormsg("jshell.err.file.exception", "jshell", resourceName, e);
+            }
+            return noStartup();
+        });
+    }
+
+    private enum DefaultStartupType {
+        DEFAULT_STARTUP("DEFAULT"),
+        DEFAULT_STARTUP_NO_MODULE_IMPORTS("DEFAULT_NO_MODULE_IMPORTS"),
+        PREVIEW_DEFAULT_STARTUP("PREVIEW_DEFAULT");
 
-        if (defaultStartup[idx] != null) {
-            return defaultStartup[idx];
+        private final String resourceName;
+
+        private DefaultStartupType(String resourceName) {
+            this.resourceName = resourceName;
         }
-        String resourceName = preview ? PREVIEW_DEFAULT_STARTUP_NAME
-                                      : DEFAULT_STARTUP_NAME;
-        try {
-            String content = readResource(resourceName);
-            return defaultStartup[idx] = new Startup(
-                    new StartupEntry(true, resourceName, content));
-        } catch (AccessDeniedException e) {
-            mh.errormsg("jshell.err.file.not.accessible", "jshell", resourceName, e.getMessage());
-        } catch (NoSuchFileException e) {
-            mh.errormsg("jshell.err.file.not.found", "jshell", resourceName);
-        } catch (Exception e) {
-            mh.errormsg("jshell.err.file.exception", "jshell", resourceName, e);
+
+        public String getResourceName() {
+            return resourceName;
         }
-        return defaultStartup[idx] = noStartup();
     }
-
 }

src/jdk.jshell/share/classes/jdk/jshell/Snippet.java

@@ -28,7 +28,6 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
-import jdk.internal.javac.PreviewFeature;
 
 /**
  * A Snippet represents a snippet of Java source code as passed to
@@ -219,9 +218,8 @@ public enum SubKind {
          * Import Module Declaration.
          * An import declaration of a module.
          * @jls 7.5.5 Import Module Declarations
-         * @since 23
+         * @since 25
          */
-        @PreviewFeature(feature=PreviewFeature.Feature.MODULE_IMPORTS, reflective=true)
         MODULE_IMPORT_SUBKIND(Kind.IMPORT),
 
         /**