revert change breaking module resolution from output path; explicit '--patch-module' compiler option enables compilation with 'module-path' instead of 'classpath'

GitOrigin-RevId: 5c22cf1b937a783aa02e298ea995c863dc8c567c

java/java-tests/testData/compileServer/incremental/java9-features/partialModuleCompilation/moduleA/src/aaa/Main.java

@@ -0,0 +1,7 @@
+package aaa;
+
+public class Main {
+  public static void main(String[] args) {
+    System.out.println("Hello");
+  }
+}

java/java-tests/testData/compileServer/incremental/java9-features/partialModuleCompilation/moduleA/src/aaa/Main.java.new

@@ -0,0 +1,7 @@
+package aaa;
+
+public class Main {
+  public static void main(String[] args) {
+    Class<?> srvClass = ppp.api.Service.class;
+  }
+}

java/java-tests/testData/compileServer/incremental/java9-features/partialModuleCompilation/moduleA/src/module-info.java

@@ -0,0 +1,3 @@
+module A {
+  requires module_lib1;
+}

jps/jps-builders-6/src/org/jetbrains/jps/javac/JpsJavacFileManager.java

@@ -2,7 +2,10 @@
 package org.jetbrains.jps.javac;
 
 import com.intellij.openapi.util.io.FileUtilRt;
-import org.jetbrains.annotations.*;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.Nls;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jps.builders.java.JavaSourceTransformer;
 import org.jetbrains.jps.javac.Iterators.BooleanFunction;
 import org.jetbrains.jps.javac.Iterators.Function;
@@ -146,11 +149,7 @@ public final class JpsJavacFileManager extends ForwardingJavaFileManager<Standar
       throw new IllegalArgumentException("Invalid kind: " + kind);
     }
     final JavaFileObject fo = super.getJavaFileForInput(location, className, kind); // todo
-    boolean isModuleInfo = "module-info".equals(className);
+    if (fo == null && !"module-info".equals(className)) {
-    if (location == StandardLocation.CLASS_OUTPUT && isModuleInfo) {
-      return null;
-    }
-    if (fo == null && !isModuleInfo) {
       // workaround javac bug (missing null-check): throwing exception here instead of returning null
       throw new FileNotFoundException("Java resource does not exist : " + location + '/' + kind + '/' + className);
     }

jps/jps-builders/src/org/jetbrains/jps/incremental/java/JavaBuilder.java

@@ -106,6 +106,7 @@ public final class JavaBuilder extends ModuleLevelBuilder {
   private static final String PROCESSOR_MODULE_PATH_OPTION = "--processor-module-path";
   private static final String SOURCE_OPTION = "-source";
   private static final String SYSTEM_OPTION = "--system";
+  private static final String PATCH_MODULE_OPTION = "--patch-module";
   private static final Set<String> FILTERED_OPTIONS = Set.of(
     TARGET_OPTION, RELEASE_OPTION, "-d"
   );
@@ -471,12 +472,15 @@ public final class JavaBuilder extends ModuleLevelBuilder {
       final Iterable<? extends File> classPath;
       final ModulePath modulePath;
       final Iterable<? extends File> upgradeModulePath;
-      if (moduleInfoFile != null) { // has modules
+      if (moduleInfoFile != null || Iterators.contains(options, PATCH_MODULE_OPTION)) { // has modules or trying to patch a module
+
         final ModulePathSplitter splitter = MODULE_PATH_SPLITTER.get(context);
         final Pair<ModulePath, Collection<File>> pair = splitter.splitPath(
           moduleInfoFile, outs.keySet(), ProjectPaths.getCompilationModulePath(chunk, false), collectAdditionalRequires(options)
         );
-        final boolean useModulePathOnly = Boolean.parseBoolean(System.getProperty(USE_MODULE_PATH_ONLY_OPTION))/*compilerConfig.useModulePathOnly()*/;
+
+        // always add everything to ModulePath if module path usagfe is forced or '--patch-module' is explicitly specified in the command line
+        final boolean useModulePathOnly = moduleInfoFile == null || Boolean.parseBoolean(System.getProperty(USE_MODULE_PATH_ONLY_OPTION))/*compilerConfig.useModulePathOnly()*/;
         if (useModulePathOnly) {
           // in Java 9, named modules are not allowed to read classes from the classpath
           // moreover, the compiler requires all transitive dependencies to be on the module path

jps/jps-builders/src/org/jetbrains/jps/incremental/java/ModulePathSplitter.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package org.jetbrains.jps.incremental.java;
 
 import com.intellij.openapi.util.Pair;
@@ -83,11 +83,11 @@ public final class ModulePathSplitter {
     myModuleNameSearch = moduleNameSearch;
   }
 
-  public Pair<ModulePath, Collection<File>> splitPath(File chunkModuleInfo, Set<? extends File> chunkOutputs, Collection<? extends File> path) {
+  public Pair<ModulePath, Collection<File>> splitPath(@Nullable File chunkModuleInfo, Set<? extends File> chunkOutputs, Collection<? extends File> path) {
     return splitPath(chunkModuleInfo, chunkOutputs, path, Collections.emptySet());
   }
 
-  public Pair<ModulePath, Collection<File>> splitPath(File chunkModuleInfo, Set<? extends File> chunkOutputs, Collection<? extends File> path, Collection<String> addReads) {
+  public Pair<ModulePath, Collection<File>> splitPath(@Nullable File chunkModuleInfo, Set<? extends File> chunkOutputs, Collection<? extends File> path, Collection<String> addReads) {
     if (myModuleFinderCreateMethod == null) {
       // the module API is not available
       return Pair.create(ModulePath.create(path), Collections.emptyList());
@@ -140,14 +140,16 @@ public final class ModulePathSplitter {
     return fName;
   }
 
-  private Set<String> collectRequired(File chunkModuleInfo, Iterable<? extends File> path) {
+  private Set<String> collectRequired(@Nullable File chunkModuleInfo, Iterable<? extends File> path) {
     final Set<String> result = new HashSet<>();
-    // first, add all requires from chunk module-info
+    if (chunkModuleInfo != null) {
-    final JavaModuleDescriptor chunkDescr = new JavaProjectBuilder(new OrderedClassLibraryBuilder()).addSourceFolder(chunkModuleInfo.getParentFile()).getDescriptor();
+      // first, add all requires from chunk module-info
-    for (JavaModuleDescriptor.JavaRequires require : chunkDescr.getRequires()) {
+      final JavaModuleDescriptor chunkDescr = new JavaProjectBuilder(new OrderedClassLibraryBuilder()).addSourceFolder(chunkModuleInfo.getParentFile()).getDescriptor();
-      final JavaModule rm = require.getModule();
+      for (JavaModuleDescriptor.JavaRequires require : chunkDescr.getRequires()) {
-      if (rm != null) {
+        final JavaModule rm = require.getModule();
-        result.add(rm.getName());
+        if (rm != null) {
+          result.add(rm.getName());
+        }
       }
     }
     for (File file : path) {

jps/jps-builders/testSrc/org/jetbrains/ether/Java9Test.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package org.jetbrains.ether;
 
 import com.intellij.openapi.projectRoots.JavaSdkVersion;
@@ -158,6 +158,24 @@ public class Java9Test extends IncrementalTestCase {
     assertTrue(classpath.contains(new File(libDir, "module_lib_3.jar")));
   }
 
+  public void testPartialModuleCompilation() {
+    setupInitialProject();
+    final Map<String, JpsModule> modules = setupModules();
+
+    assertEquals(1, modules.size());
+
+    final JpsModule module = modules.values().iterator().next();
+    final File libDir = new File(getAbsolutePath("lib"));
+    for (File jarFile : libDir.listFiles((dir, name) -> name.endsWith(".jar"))) {
+      JpsLibrary lib = addLibrary(jarFile.getName(), jarFile);
+      JpsModuleRootModificationUtil.addDependency(module, lib, JpsJavaDependencyScope.COMPILE, false);
+    }
+
+    doBuild(CompileScopeTestBuilder.rebuild().allModules()).assertSuccessful();
+    modify(0);
+    doBuild(CompileScopeTestBuilder.make().allModules()).assertSuccessful();
+  }
+
 
   public void testExplodedAutoModule() {
     setupInitialProject();

plugins/maven/src/test/java/org/jetbrains/idea/maven/compiler/MultiReleaseOutputTest.kt

@@ -93,6 +93,9 @@ class MultiReleaseOutputTest : MavenCompilingTestCase() {
   }
 
 
+/*
+ todo: commented until IDEA-367746 is fixed
+
   @Test
   fun `test java module compilation`() = runBlocking {
     createProjectSubFile("src/main/java/module-info.java", """
@@ -107,7 +110,7 @@ class MultiReleaseOutputTest : MavenCompilingTestCase() {
       <artifactId>project</artifactId>
       <version>1</version>
       <properties>
-        <maven.compiler.release>9</maven.compiler.release>  
+        <maven.compiler.release>9</maven.compiler.release>
       </properties>
       <build>
         <plugins>
@@ -123,6 +126,10 @@ class MultiReleaseOutputTest : MavenCompilingTestCase() {
                     <compileSourceRoots>
                       <root>${'$'}{project.basedir}/src/main/java-additional</root>
                     </compileSourceRoots>
+                    <compilerArgs>
+                      <arg>--patch-module</arg>
+                      <arg>project=${'$'}{project.basedir}/src/main/java-additional</arg>
+                    </compilerArgs>
                   </configuration>
                 </execution>
               </executions>
@@ -145,4 +152,5 @@ class MultiReleaseOutputTest : MavenCompilingTestCase() {
     assertExists("target/classes/A.class")
     assertExists("target/classes/B.class")
   }
+*/
 }