Swiftiomatic

AST-accurate Swift linting, formatting, and code analysis. A fork of apple/swift-format with additional rules drawn from SwiftFormat and SwiftLint.

The sm binary is a drop-in replacement for swift-format: the same format, lint, and dump-configuration subcommands and flags, plus extras (doctor, link, update).

Configuration

Configuration is JSON5. Format and lint are both per-rule, with universal layout settings (line length, indentation, line breaks) alongside.

{
    "$schema": "https://raw.githubusercontent.com/toba/swiftiomatic/refs/heads/main/schema.json",
    "version": 8,
    "indentation": { "unit": { "spaces": 4 }, "tabWidth": 8 },
    "lineBreaks": { "lineLength": 100, "respectExistingLineBreaks": true }
}

Each rule accepts "rewrite": true | false (format side) and "lint": "no" | "warn" | "error" (lint side). Format rules default to active; lint rules default to "warn".

Ignoring rules in source

Suppress a rule from a comment with // sm:ignore. Swiftiomatic recognizes the sm: prefix alone, so the upstream // swift-format-ignore and // swift-format-ignore-file comments have no effect.

A bare directive suppresses every rule. Naming rules after it suppresses only those. Both the configuration key (useTrailingClosures) and the type name (UseTrailingClosures) resolve.

Form	Scope
// sm:ignore on its own line	from that line to the end of the file
// sm:ignore:next on its own line	the next statement or member
// sm:ignore after code	that statement only

// both rules off for the rest of the file
// sm:ignore fileLength, typeBodyLength

// one rule off for the call below
// sm:ignore:next useTrailingClosures
try withoutActuallyEscaping({ ... }, do: { ... })

let x = "trouble"  // sm:ignore

Text after the rule list is a free-form comment: // sm:ignore:next UseSelfNotTypeName the generic parameter shadows it.

A directive disables the pretty printer too, so the node it covers keeps its existing line breaks and indentation.

On a multi-line statement, a trailing directive attaches on the opening line or the closing line. An interior line scopes it to the inner statement instead. See Documentation/IgnoringSource.md for the full rules.

CLI

sm format Sources/             # auto-fix in place
sm lint Sources/               # report findings without modifying files
sm dump-configuration          # print the resolved configuration
sm doctor                      # diagnose installation/configuration issues
sm link                        # install the toolchain symlink in every installed Xcode
sm update                      # update the configuration to the current schema version

Installation

Build and install:

swift build -c release
cp .build/arm64-apple-macosx/release/sm /opt/homebrew/Cellar/sm/<version>/bin/sm

For Xcode IDE integration ("Format with swift-format" and the SPM plugins), see CLAUDE.md.