[Java. Code Formatting] IDEA-388356 Restore old behaviour for tabs when doing alignment

(cherry picked from commit 20a632fbf2c6281ebf957a7909ac655215334bc9)

IJ-CR-212269

GitOrigin-RevId: c9f45723c2229016952141387a2a251317618b0e

java/java-tests/testData/psi/formatter/java/textBlock/NonIntegerNumberOfTabs_after.java

@@ -1,8 +1,8 @@
 public class Formatter {
 	void foo() {
 		String sss = """
-		             
-		             
-		             foo""";
+					 
+					 
+					 foo""";
 	}
 }

java/java-tests/testData/psi/formatter/tabIndenting/Tab2_after.java

@@ -1,8 +1,9 @@
+
 class A {
 		int a;
 
 		void foo(int a,
-		         int b) {
+						 int b) {
 				boolean b;
 		}
 }

java/java-tests/testData/psi/formatter/tabIndenting/Tab4_after.java

@@ -1,8 +1,9 @@
+
 class A {
 	int a;
 
 	void foo(int a,
-	         int b) {
+			 int b) {
 		boolean b;
 	}
 }

java/java-tests/testData/psi/formatter/tabIndenting/Tab8_after.java

@@ -1,8 +1,9 @@
+
 class A {
     int a;
 
     void foo(int a,
-             int b) {
+	     int b) {
 	boolean b;
     }
 }

java/java-tests/testData/psi/formatter/tabIndenting/methodAlignment.java

@@ -0,0 +1,8 @@
+public class A {
+	public void foo1(int i1, int i2,
+           int i3, int i4,
+           int i5, int i6,
+           int i7) {
+
+  }
+}

java/java-tests/testData/psi/formatter/tabIndenting/methodAlignment_after.java

@@ -0,0 +1,8 @@
+public class A {
+	public void foo1(int i1, int i2,
+					 int i3, int i4,
+					 int i5, int i6,
+					 int i7) {
+
+	}
+}

java/java-tests/testSrc/com/intellij/java/psi/formatter/java/TabIndentingTest.java

@@ -1,22 +1,9 @@
-/*
- * Copyright 2000-2017 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2026 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.java.psi.formatter.java;
 
 import com.intellij.application.options.CodeStyle;
 import com.intellij.ide.highlighter.JavaFileType;
+import com.intellij.lang.java.JavaLanguage;
 import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.application.ex.PathManagerEx;
 import com.intellij.openapi.command.CommandProcessor;
@@ -25,6 +12,7 @@ import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.psi.PsiFile;
 import com.intellij.psi.codeStyle.CodeStyleManager;
 import com.intellij.psi.codeStyle.CodeStyleSettings;
+import com.intellij.psi.codeStyle.CommonCodeStyleSettings;
 import com.intellij.testFramework.LightIdeaTestCase;
 import com.intellij.util.IncorrectOperationException;
 
@@ -94,6 +82,15 @@ public class TabIndentingTest extends LightIdeaTestCase {
     doTest("moreTabsInComments.java", "moreTabsInComments_after.java");
   }
 
+  public void testAlignmentWithTabs() throws Exception {
+    CodeStyleSettings settings = CodeStyle.getSettings(getProject());
+    settings.getIndentOptions(JavaFileType.INSTANCE).USE_TAB_CHARACTER = true;
+    settings.getIndentOptions(JavaFileType.INSTANCE).TAB_SIZE = 4;
+    settings.getCommonSettings(JavaLanguage.INSTANCE).METHOD_PARAMETERS_WRAP = CommonCodeStyleSettings.WRAP_AS_NEEDED;
+    settings.getCommonSettings(JavaLanguage.INSTANCE).ALIGN_MULTILINE_PARAMETERS = true;
+    doTest("methodAlignment.java", "methodAlignment_after.java");
+  }
+
   private void doTest(String fileNameBefore, String fileNameAfter) throws Exception {
     String text = loadFile(fileNameBefore);
     final PsiFile file = createFile(fileNameBefore, text);

platform/code-style-impl/resources/META-INF/CodeStyle.xml

@@ -43,6 +43,10 @@
       <with attribute="implementationClass" implements="com.intellij.openapi.editor.IndentStrategy"/>
     </extensionPoint>
 
+    <extensionPoint name="lang.formatter.alignmentWhitespacePolicy" beanClass="com.intellij.lang.LanguageExtensionPoint" dynamic="true">
+      <with attribute="implementationClass" implements="com.intellij.formatting.AlignmentWhitespacePolicy"/>
+    </extensionPoint>
+
     <extensionPoint name="fileIndentOptionsProvider" interface="com.intellij.psi.codeStyle.FileIndentOptionsProvider" dynamic="true"/>
     <extensionPoint name="fileCodeStyleProvider" interface="com.intellij.psi.codeStyle.FileCodeStyleProvider" dynamic="true"/>
     <extensionPoint name="codeFormattingDataPreparer" interface="com.intellij.psi.impl.source.codeStyle.CodeFormattingDataPreparer" dynamic="true"/>

platform/code-style-impl/src/com/intellij/formatting/AbstractBlockAlignmentProcessor.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 2000-2026 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.formatting;
 
 import org.jetbrains.annotations.ApiStatus;
@@ -70,8 +70,11 @@ public abstract class AbstractBlockAlignmentProcessor implements BlockAlignmentP
 
     WhiteSpace previousWhiteSpace = offsetResponsibleBlock.getWhiteSpace();
     previousWhiteSpace.setSpaces(previousWhiteSpace.getSpaces() - diff, previousWhiteSpace.getIndentOffset());
-    // Backward shift introduces alignment spaces. Keep those exempt from tab conversion.
-    previousWhiteSpace.setForceSkipTabulationsUsage(true);
+    if (!previousWhiteSpace.containsLineFeeds() ||
+        LanguageAlignmentWhitespacePolicy.useSpacesForAlignment(offsetResponsibleBlock)) {
+      // Avoid tabulations usage for aligning blocks that are not the first blocks on a line.
+      previousWhiteSpace.setForceSkipTabulationsUsage(true);
+    }
 
     return Result.BACKWARD_BLOCK_ALIGNED;
   }

platform/code-style-impl/src/com/intellij/formatting/AlignmentWhitespacePolicy.java

@@ -0,0 +1,13 @@
+// Copyright 2000-2026 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.formatting;
+
+import org.jetbrains.annotations.ApiStatus;
+
+/**
+ * This policy allows enforcing using spaces for alignment that is necessary for some languages even if USE_TAB_CHARACTER option is enabled.
+ * @see WhiteSpace#setForceSkipTabulationsUsage(boolean)
+ */
+@ApiStatus.Internal
+public interface AlignmentWhitespacePolicy {
+  boolean useSpacesForAlignment();
+}

platform/code-style-impl/src/com/intellij/formatting/LanguageAlignmentWhitespacePolicy.java

@@ -0,0 +1,24 @@
+// Copyright 2000-2026 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.formatting;
+
+import com.intellij.lang.Language;
+import com.intellij.lang.LanguageExtension;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.Nullable;
+
+@ApiStatus.Internal
+public final class LanguageAlignmentWhitespacePolicy extends LanguageExtension<AlignmentWhitespacePolicy> {
+  private static final LanguageAlignmentWhitespacePolicy INSTANCE = new LanguageAlignmentWhitespacePolicy();
+
+  private LanguageAlignmentWhitespacePolicy() {
+    super("com.intellij.lang.formatter.alignmentWhitespacePolicy");
+  }
+
+  static boolean useSpacesForAlignment(@Nullable AbstractBlockWrapper block) {
+    if (block == null) return false;
+    Language language = block.getLanguage();
+    if (language == null) return false;
+    AlignmentWhitespacePolicy policy = INSTANCE.forLanguage(language);
+    return policy != null && policy.useSpacesForAlignment();
+  }
+}

platform/code-style-impl/src/com/intellij/formatting/LeftEdgeAlignmentProcessor.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 2000-2026 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.formatting;
 
 import org.jetbrains.annotations.ApiStatus;
@@ -44,7 +44,8 @@ public final class LeftEdgeAlignmentProcessor extends AbstractBlockAlignmentProc
   protected boolean applyIndentToTheFirstBlockOnLine(@NotNull IndentData alignmentAnchorIndent, @NotNull Context context) {
     WhiteSpace whiteSpace = context.targetBlock().getWhiteSpace();
     whiteSpace.setSpaces(alignmentAnchorIndent.getSpaces(), alignmentAnchorIndent.getIndentSpaces());
-    if (alignmentAnchorIndent.getSpaces() > 0) {
+    if (alignmentAnchorIndent.getSpaces() > 0 &&
+        LanguageAlignmentWhitespacePolicy.useSpacesForAlignment(context.targetBlock())) {
       // Alignment spaces should not be converted into tabs
       whiteSpace.setForceSkipTabulationsUsage(true);
     }

platform/code-style-impl/src/com/intellij/formatting/RightEdgeAlignmentProcessor.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 2000-2026 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.formatting;
 
 import org.jetbrains.annotations.ApiStatus;
@@ -48,7 +48,7 @@ public final class RightEdgeAlignmentProcessor extends AbstractBlockAlignmentPro
 
     if (indentSpaces >= 0) {
       whiteSpace.setSpaces(spaces, indentSpaces);
-      if (spaces > 0) {
+      if (spaces > 0 && LanguageAlignmentWhitespacePolicy.useSpacesForAlignment(context.targetBlock())) {
         // Alignment spaces should not be converted into tabs
         whiteSpace.setForceSkipTabulationsUsage(true);
       }
@@ -82,7 +82,7 @@ public final class RightEdgeAlignmentProcessor extends AbstractBlockAlignmentPro
           }
         }
         whiteSpace.setSpaces(spaces, indentSpaces);
-        if (spaces > 0) {
+        if (spaces > 0 && LanguageAlignmentWhitespacePolicy.useSpacesForAlignment(context.targetBlock())) {
           // Alignment spaces should not be converted into tabs
           whiteSpace.setForceSkipTabulationsUsage(true);
         }

platform/code-style-impl/src/com/intellij/formatting/WhiteSpace.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2026 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 
 package com.intellij.formatting;
 
@@ -444,9 +444,7 @@ public final class WhiteSpace {
    * will be used for tab representation if there are non-white space symbols before it (IJ editor may use different number of columns
    * for single tabulation symbol representation).
    * <p/>
-   * Hence, we can ask current white space object to avoid using tabulation symbols for alignment.
-   * Tab usage is not necessarily suppressed entirely: if this whitespace starts a new line, tabs may still be
-   * used for indentation while alignment remains spaces.
+   * Some languages may apply this option to disable the usage of tabulation during alignment. See {@link AlignmentWhitespacePolicy}.
    *
    * @param skip   indicates if tabulation symbols usage should be suppressed for alignment
    */