CI: Swift 6.2 compiler bug in swift-configuration #23
Description
Issue
CI builds on Windows and Ubuntu Noble with Swift 6.2.x stable toolchains fail due to a known Swift compiler bug when compiling Apple's Swift Configuration library.
Root Cause
Swift 6.2.x compilers from swift.org have assertions enabled, which triggers a SIL verification crash in FileProvider.swift:176:
SIL verification failed: inconsistent stack heights entering basic block:
state.Stack == foundState.Stack || isUnreachable()
Upstream Issue: apple/swift-configuration#128
Affected Platforms
| Platform | Swift Version | Status |
|---|---|---|
| Windows 2022 | Swift 6.2-RELEASE | ❌ Failed |
| Windows 2025 | Swift 6.2-RELEASE | ❌ Failed |
| Ubuntu Noble | Swift 6.2 stable | ❌ Failed |
| Ubuntu Noble | Swift 6.2/6.3 nightly | ✅ Passed |
| macOS | Xcode 26.2 | ✅ Passed |
Workaround
Since CelestraCloud only uses CommandLineArgumentsProvider and EnvironmentVariablesProvider, we can remove the .defaults trait (which includes JSON/FileProvider support) from the Swift Configuration dependency:
// Package.swift
.package(
url: "https://github.com/apple/swift-configuration.git",
from: "1.0.0",
traits: ["CommandLineArguments"] // Removed .defaults
)This avoids compiling FileProvider entirely, sidestepping the compiler bug.
Resolution
The bug is already fixed in Swift 6.3. Once Swift 6.3 stable is released, we can re-add .defaults if needed.