Add support for .swift-format-ignore files by bkhouri · Pull Request #1156 · swiftlang/swift-format

bkhouri · 2026-02-16T08:59:38Z

Add supports for file-based ignoring using .swift-format-ignore files. These files allow a developer to specify patterns for files and directories that should be completely excluded from formatting and linting operations.

Fixes: #870

Sources/swift-format/Frontend/Frontend.swift

Sources/SwiftFormat/Utilities/IgnoreManager.swift

Sources/SwiftFormat/Utilities/FileIterator.swift

Sources/swift-format/Frontend/Frontend.swift

plans/swift-format-ignore-architecture.md

Sources/SwiftFormat/Utilities/BaseDirectoryDeterminer.swift

Sources/SwiftFormat/Utilities/IgnoreManager.swift

Sources/swift-format/Frontend/Frontend.swift

Sources/SwiftFormat/Utilities/IgnoreManager.swift

Sources/SwiftFormat/Utilities/FileIterator.swift

Sources/swift-format/Frontend/Frontend.swift

Sources/SwiftFormat/Utilities/FileIterator.swift

Documentation/IgnoringSource.md

Sources/SwiftFormat/Utilities/GitIgnorePattern.swift

Sources/SwiftFormat/Utilities/IgnoreManager.swift

Tests/SwiftFormatTests/Utilities/GitIgnorePatternTests.swift

bkhouri · 2026-02-17T21:14:07Z

@allevato : GitHub is not allowing me to directly reply to one of you comments,

Right, we collect the files that need to be worked on in the main thread and only once we have that list do we act concurrently if --parallel is set. You shouldn't need any locking here; if you look at ConfigurationLoader in the frontend module, you'll see that its cache doesn't do any locking either.

I removed the locking mechanism, and also marked the IgnoreManagerTests to run serially to avoid any collision between tests since the IgnoreManager is not thread safe.

bkhouri · 2026-02-17T21:15:19Z

@rintaro : I am unable to reply directly to one of your comments

Do we really need the lock in the first place? As far as I can see FileIterator is only used in the main thread.

I removed the locking mechanism, and also marked the IgnoreManagerTests to run serially to avoid any collision between tests since IgnoreManager is not thread safe.

Sources/SwiftFormat/Utilities/FileIterator.swift

rintaro · 2026-02-18T04:38:10Z

Sources/SwiftFormat/Utilities/FileIterator.swift

+        // Apply ignore filtering
+        if self.ignoreManager.shouldIgnore(file: item, isDirectory: false) {
+          output = nil
+          continue  // Skip this file and continue to next
+        }


This will be checked in next() again. I don't think we need this check here.

in next(), we check whether directories should be ignored. Here, we are checking whether files should be ignored. Both are needed.

You removed the another check for files in next().
That means swift-format path/to/File.swift would perform formatting the specified file even if that file is .swift-format-ignore. Is that the desired behavior?

If so, what about the directories? E.g. swift-format --recursive path/to/Sources/MyLibrary/generated/ Should this directory be formatted even if it's ignored in .swift-format-ignore in the parent directories?

If a file matches a pattern found in .swift-format-ignore file, it should not be formatted unless the pattern is negated.

A pattern in .swift-format-ignore can apply to files, or to directories.

rintaro · 2026-02-18T04:39:16Z

Sources/SwiftFormat/Utilities/FileIterator.swift

+    urls: [URL],
+    followSymlinks: Bool,
+    workingDirectory: URL = URL(fileURLWithPath: "."),
+    ignoreManager: IgnoreManager


Suggested change

ignoreManager: IgnoreManager

ignoreManager: IgnoreManager = IgnoreManager()

then we don't need the additional init(urls:followSymlinks:workingDirectory:) below. Though I still not sure if this needs to be injectable.

I kept this here in the event we want to have dependency injection testing. I will change the access modifier to package

rintaro · 2026-02-25T18:22:35Z

Sources/SwiftFormat/Utilities/IgnoreManager.swift

+      if currentDir.isRoot {
+        break  // We've reached the root


I thought you once implemented to make "baseDirectory" the path having .swift-format file. But apparently you removed it? Now baseDirectoryCache: [URL: URL] is not used anymore.

Stopping at .swift-format directory is important because otherwise the behavior would be unstable. For example the root directory / might have .swift-format-ignore ignoring everything. The tests would fail in such machines.

I re-introduced this, and added automated test cases that verify some integration with .swift-format and .swift-format-ignore. Thanks for bringing this my attention.

Add supports for file-based ignoring using `.swift-format-ignore` files. These files allow a developer to specify patterns for files and directories that should be completely excluded from formatting and linting operations. Fixes: swiftlang#870

bkhouri force-pushed the t/main/gh_870_add_swift-format-ignore-file-support branch 2 times, most recently from 8ba8eac to 23077c1 Compare February 16, 2026 11:44

bkhouri marked this pull request as ready for review February 16, 2026 12:02

bkhouri requested review from allevato, hamishknight, hborla and rintaro as code owners February 16, 2026 12:02

rintaro reviewed Feb 16, 2026

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bkhouri force-pushed the t/main/gh_870_add_swift-format-ignore-file-support branch 3 times, most recently from ef2c9fe to aec3db3 Compare February 17, 2026 21:11

bkhouri force-pushed the t/main/gh_870_add_swift-format-ignore-file-support branch from aec3db3 to d4662ec Compare February 17, 2026 21:20

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bkhouri force-pushed the t/main/gh_870_add_swift-format-ignore-file-support branch 4 times, most recently from 2ba9d9d to 0207c96 Compare February 19, 2026 13:20

bkhouri requested review from allevato and rintaro February 20, 2026 03:15

bkhouri marked this pull request as draft February 20, 2026 03:15

bkhouri marked this pull request as ready for review February 20, 2026 03:15

bkhouri force-pushed the t/main/gh_870_add_swift-format-ignore-file-support branch 2 times, most recently from 7fbf1b4 to 331ddb4 Compare February 25, 2026 06:07

rintaro reviewed Feb 25, 2026

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bkhouri force-pushed the t/main/gh_870_add_swift-format-ignore-file-support branch 3 times, most recently from 5772f0d to 2ee590a Compare March 8, 2026 20:11

bkhouri force-pushed the t/main/gh_870_add_swift-format-ignore-file-support branch from 2ee590a to 6c614da Compare March 9, 2026 13:45

bkhouri marked this pull request as draft March 9, 2026 15:29

	ignoreManager: IgnoreManager
	ignoreManager: IgnoreManager = IgnoreManager()

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bkhouri commented Feb 16, 2026

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bkhouri commented Feb 17, 2026

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