Add lint suppression API to maven (#2629)

Author: nedtwigg

CHANGES.md

@@ -26,6 +26,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 * `GitPrePushHookInstaller` uses a lock to run gracefully if it is called many times in parallel. ([#2570](https://github.com/diffplug/spotless/pull/2570))
 ### Added
 * Add a `lint` mode to `ReplaceRegexStep` ([#2571](https://github.com/diffplug/spotless/pull/2571))
+* `LintSuppression` now enforces unix-style paths in its `setPath` and `relativizeAsUnix` methods. ([#2629](https://github.com/diffplug/spotless/pull/2629))
 
 ## [3.3.1] - 2025-07-21
 ### Fixed

lib-extra/src/main/java/com/diffplug/spotless/extra/integration/DiffMessageFormatter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2024 DiffPlug
+ * Copyright 2016-2025 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -292,7 +292,7 @@ private static Map.Entry<Integer, String> diffWhitespaceLineEndings(String dirty
 	}
 
 	private static int getLineOfFirstDifference(EditList edits) {
-		return edits.stream().mapToInt(Edit::getBeginA).min().getAsInt();
+		return edits.stream().mapToInt(Edit::getBeginA).min().orElse(0);
 	}
 
 	private static final CharMatcher NEWLINE_MATCHER = CharMatcher.is('\n');

lib/src/main/java/com/diffplug/spotless/LintSuppression.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2024 DiffPlug
+ * Copyright 2024-2025 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,8 +15,11 @@
  */
 package com.diffplug.spotless;
 
+import java.io.File;
 import java.util.Objects;
 
+import javax.annotation.Nullable;
+
 public class LintSuppression implements java.io.Serializable {
 	private static final long serialVersionUID = 1L;
 
@@ -30,6 +33,9 @@ public String getPath() {
 	}
 
 	public void setPath(String path) {
+		if (path.indexOf('\\') != -1) {
+			throw new IllegalArgumentException("Path must use only unix style path separator `/`, this was " + path);
+		}
 		this.path = Objects.requireNonNull(path);
 	}
 
@@ -90,4 +96,20 @@ public String toString() {
 				", code='" + shortCode + '\'' +
 				'}';
 	}
+
+	/**
+	 * Returns the relative path between root and dest, or null if dest is not a
+	 * child of root. Guaranteed to only have unix-separators.
+	 */
+	public static @Nullable String relativizeAsUnix(File root, File dest) {
+		String rootPath = root.getAbsolutePath();
+		String destPath = dest.getAbsolutePath();
+		if (!destPath.startsWith(rootPath)) {
+			return null;
+		} else {
+			String relativized = destPath.substring(rootPath.length());
+			String unixified = relativized.replace('\\', '/');
+			return unixified.startsWith("/") ? unixified.substring(1) : unixified;
+		}
+	}
 }

lib/src/main/java/com/diffplug/spotless/generic/ReplaceRegexStep.java

@@ -90,7 +90,12 @@ public List<Lint> lint(String raw, File file) {
 					var matcher = regex.matcher(raw);
 					while (matcher.find()) {
 						int line = 1 + (int) raw.codePoints().limit(matcher.start()).filter(c -> c == '\n').count();
-						lints.add(Lint.atLine(line, matcher.group(0), lintDetail));
+						String errorCode = matcher.group(0).trim();
+						int firstNewline = errorCode.indexOf("\n");
+						if (firstNewline != -1) {
+							errorCode = errorCode.substring(0, firstNewline);
+						}
+						lints.add(Lint.atLine(line, errorCode, lintDetail));
 					}
 					return lints;
 				}

plugin-gradle/CHANGES.md

@@ -6,6 +6,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 ### Changed
 * **BREAKING** Bump the required Gradle to `7.3` and required Java to `17`. ([#2375](https://github.com/diffplug/spotless/issues/2375), [#2540](https://github.com/diffplug/spotless/pull/2540))
 * **BREAKING** `spotlessInstallGitPrePushHook` task is now installed only on the root project. ([#2570](https://github.com/diffplug/spotless/pull/2570))
+* **BREAKING** `LintSuppression` now enforces unix-style paths in its `setPath` method. ([#2629](https://github.com/diffplug/spotless/pull/2629))
 * Running `spotlessCheck` with violations unilaterally produces the error message `Run './gradlew spotlessApply' to fix these violations`. ([#2592](https://github.com/diffplug/spotless/issues/2592))
 * Bump JGit from `6.10.1` to `7.3.0` ([#2257](https://github.com/diffplug/spotless/pull/2257))
   * Adds support for worktrees (fixes [#1765](https://github.com/diffplug/spotless/issues/1765))
@@ -16,7 +17,6 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
   * **BREAKING** use `TrailingCommaManagementStrategy` enum instead of `manageTrailingCommas` boolean configuration option
 * Bump default `ktlint` version to latest `1.5.0` -> `1.7.1`. ([#2555](https://github.com/diffplug/spotless/pull/2555))
 * Bump default `palantir-java-format` version to latest `2.57.0` -> `2.71.0`.
-
 ### Fixed
 * Respect system gitconfig when performing git operations ([#2404](https://github.com/diffplug/spotless/issues/2404))
 * Fix `spaceBeforeSeparator` in Jackson formatter. ([#2103](https://github.com/diffplug/spotless/pull/2103))

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/FormatExtension.java

@@ -347,27 +347,12 @@ private final FileCollection parseTargetIsExclude(Object target, boolean isExclu
 	}
 
 	private static void relativizeIfSubdir(List<String> relativePaths, File root, File dest) {
-		String relativized = relativize(root, dest);
+		String relativized = LintSuppression.relativizeAsUnix(root, dest);
 		if (relativized != null) {
 			relativePaths.add(relativized);
 		}
 	}
 
-	/**
-	 * Returns the relative path between root and dest, or null if dest is not a
-	 * child of root.
-	 */
-	static @Nullable String relativize(File root, File dest) {
-		String rootPath = root.getAbsolutePath();
-		String destPath = dest.getAbsolutePath();
-		if (!destPath.startsWith(rootPath)) {
-			return null;
-		} else {
-			String relativized = destPath.substring(rootPath.length());
-			return relativized.startsWith("/") || relativized.startsWith("\\") ? relativized.substring(1) : relativized;
-		}
-	}
-
 	/** The steps that need to be added. */
 	protected final List<FormatterStep> steps = new ArrayList<>();
 

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/SpotlessTaskImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2024 DiffPlug
+ * Copyright 2016-2025 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -45,6 +45,7 @@
 import com.diffplug.spotless.Formatter;
 import com.diffplug.spotless.Lint;
 import com.diffplug.spotless.LintState;
+import com.diffplug.spotless.LintSuppression;
 import com.diffplug.spotless.extra.GitRatchet;
 
 @CacheableTask
@@ -101,7 +102,7 @@ public void performAction(InputChanges inputs) throws Exception {
 			for (FileChange fileChange : inputs.getFileChanges(target)) {
 				File input = fileChange.getFile();
 				File projectDir = getProjectDir().get().getAsFile();
-				String relativePath = FormatExtension.relativize(projectDir, input);
+				String relativePath = LintSuppression.relativizeAsUnix(projectDir, input);
 				if (relativePath == null) {
 					throw new IllegalArgumentException(StringPrinter.buildString(printer -> {
 						printer.println("Spotless error! All target files must be within the project dir.");

plugin-gradle/src/test/java/com/diffplug/gradle/spotless/FileTreeTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2021 DiffPlug
+ * Copyright 2016-2025 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,8 +15,6 @@
  */
 package com.diffplug.gradle.spotless;
 
-import static com.diffplug.gradle.spotless.FormatExtension.relativize;
-
 import java.io.File;
 import java.io.IOException;
 
@@ -26,6 +24,7 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
+import com.diffplug.spotless.LintSuppression;
 import com.diffplug.spotless.ResourceHarness;
 import com.diffplug.spotless.TestProvisioner;
 
@@ -51,7 +50,7 @@ void absolutePathDoesntWork() throws IOException {
 	void relativePathDoes() throws IOException {
 		File someFile = setFile("someFolder/someFile").toContent("");
 		File someFolder = someFile.getParentFile();
-		fileTree.exclude(relativize(rootFolder(), someFolder));
+		fileTree.exclude(LintSuppression.relativizeAsUnix(rootFolder(), someFolder));
 		Assertions.assertThat(fileTree).containsExactlyInAnyOrder();
 	}
 }

plugin-maven/CHANGES.md

@@ -17,6 +17,8 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 * Bump default `palantir-java-format` version to latest `2.57.0` -> `2.71.0`.
 ### Fixed
 * Fix `spaceBeforeSeparator` in Jackson formatter. ([#2103](https://github.com/diffplug/spotless/pull/2103))
+### Added
+* `<lintSupressions>` API ([#2309](https://github.com/diffplug/spotless/issues/2309))
 
 ## [2.46.1] - 2025-07-21
 ### Fixed

plugin-maven/README.md

@@ -1944,6 +1944,64 @@ By default, `spotless:check` is bound to the `verify` phase.  You might want to
 - set `-Dspotless.check.skip=true` at the command line
 - set `spotless.check.skip` to `true` in the `<properties>` section of the `pom.xml`
 
+### Suppressing lint errors
+
+Sometimes Spotless will encounter lint errors that can't be auto-fixed. For example, if you run `mvn spotless:check`, you might see:
+
+```
+[ERROR] Unable to format file src/main/java/com/example/App.java
+[ERROR] Step 'removeWildcardImports' found problem in 'App.java':
+[ERROR]   Do not use wildcard imports
+```
+
+To suppress these lints, you can use the `<lintSuppressions>` configuration:
+
+```xml
+<plugin>
+  <groupId>com.diffplug.spotless</groupId>
+  <artifactId>spotless-maven-plugin</artifactId>
+  <version>${spotless.version}</version>
+  <configuration>
+    <java>
+      <removeWildcardImports/>
+    </java>
+    <lintSuppressions>
+      <lintSuppression>
+        <path>src/main/java/com/example/App.java</path>
+        <step>removeWildcardImports</step>
+        <shortCode>*</shortCode>
+      </lintSuppression>
+    </lintSuppressions>
+  </configuration>
+</plugin>
+```
+
+Each `<lintSuppression>` can match by:
+- `<path>` - file path (supports wildcards like `*`)
+- `<step>` - step name (supports wildcards like `*`)
+- `<shortCode>` - specific error code (supports wildcards like `*`)
+
+You can suppress multiple patterns:
+
+```xml
+<lintSuppressions>
+  <!-- Suppress all wildcard import errors in legacy code -->
+  <lintSuppression>
+    <path>src/main/java/com/example/legacy/*</path>
+    <step>removeWildcardImports</step>
+    <shortCode>*</shortCode>
+  </lintSuppression>
+  <!-- Suppress all errors from a specific step -->
+  <lintSuppression>
+    <path>*</path>
+    <step>removeWildcardImports</step>
+    <shortCode>*</shortCode>
+  </lintSuppression>
+</lintSuppressions>
+```
+
+Spotless is primarily a formatter, _not_ a linter. In our opinion, a linter is just a broken formatter. But formatters do break sometimes, and representing these failures as lints that can be suppressed is more useful than just giving up.
+
 <a name="preview"></a>
 
 ## How do I preview what `mvn spotless:apply` will do?