With this change, it's now possible to add native custom rules when
building SwiftLint via Bazel (possible as of
https://github.com/realm/SwiftLint/pull/4038).
First, add a local bazel repository where custom rules will be defined:
```python
local_repository(
name = "swiftlint_extra_rules",
path = "swiftlint_extra_rules",
)
```
Then in the extra rules directory, add an empty `WORKSPACE` and a
`BUILD` file with the following contents:
```python
filegroup(
name = "extra_rules",
srcs = glob(["*.swift"]),
visibility = ["//visibility:public"],
)
```
To add a rule (for example, `MyPrivateRule`) add the following two
files:
```swift
// ExtraRules.swift
func extraRules() -> [Rule.Type] {
[
MyPrivateRule.self,
]
}
```
```swift
// MyPrivateRule.swift
import SourceKittenFramework
struct MyPrivateRule: ConfigurationProviderRule {
var configuration = SeverityConfiguration(.error)
init() {}
static let description = RuleDescription(
identifier: "my_private_rule",
name: "My Private Rule",
description: "This is my private rule.",
kind: .idiomatic
)
func validate(file: SwiftLintFile) -> [StyleViolation] {
// ...
}
}
```
Then you can reference the rule in your configuration or source files
as though they were built in to the official SwiftLint repo.
Recent changes to the linter cache made it correctly invalidate previous
results when custom native rules are edited.
This will unblock using Swift Concurrency features and updating to the
latest versions of Swift Argument Parser.
This won't drop support for linting projects with an older toolchain /
Xcode selected, as long as SwiftLint was _built_ with 5.6+ and is
_running_ on macOS 12+. So the main breaking change for end users here
is requiring macOS 12 to run.
However, the upside to using Swift Concurrency features is worth the
breaking change in my opinion. Also being able to stay on recent Swift
Argument Parser releases.
JP Simard