`diagnose-api-breaking-changes` reports removal of SPI

[ahoppen]

Removing SPI is considered as a breaking change in diagnose-api-breaking-changes. I wouldn’t consider SPI part of a package’s public API and thus don’t think it should be considered in the API breakages.

To reproduce run:

#!/usr/bin/env bash

cd $(mktemp -d)
echo $(realpath .)

echo '
// swift-tools-version: 6.0

import PackageDescription

let package = Package(
  name: "mypackage",
  products: [
    .library(name: "mypackage", targets: ["mypackage"])
  ],
  targets: [
    .target(name: "mypackage")
  ]
)
' > Package.swift

mkdir -p Sources/mypackage

echo '@_spi(MySPI) public let myPublicString: String = "ABC"' > Sources/mypackage/mypackage.swift

git init
git add Package.swift Sources/mypackage/mypackage.swift
git commit -m "Initial commit"
git tag 1.0.0

echo '' > Sources/mypackage/mypackage.swift

swift package diagnose-api-breaking-changes 1.0.0

This is blocking swiftlang/swift-syntax#3010

[plemarquand]

SPM calls out to the APIDigester tool in the toolchain to compute breaking changes. This would have to addressed there. Transferring the issue to the swift repo.