Outputs of describe command contains warnings.

[mtj0928]

Is it reproducible with SwiftPM command-line tools: swift build, swift test, swift package etc?

• Confirmed reproduction steps with SwiftPM CLI. The description text must include reproduction steps with either of command-line SwiftPM commands, swift build, swift test, swift package etc.

Description

The describe command can include warnings even when I specify JSON as the output format, if the package contains issues related to resources.

This seems the cause. The code emits the warning to stdout using print.

swift-package-manager/Sources/PackageLoading/TargetSourcesBuilder.swift

Line 193 in db9fef2

print("Found unhandled resource at \(resource.path)")

Because of this, I can’t parse the output as JSON.
While the resource issues in the package should be fixed, the describe command itself should avoid emitting warnings using print.

Expected behavior

The command should not emit the issue to stdout

Actual behavior

The outputs contains error message.

$ swift package describe --type json
Found unhandled resource at ..../Sources/sample/Resources // ← This line should not be contained.
{
  ...
}

Steps to reproduce

1. Make a new package sample

$ swift package init --type library --name sample  

2. Make a directory Resources to Sources/sample

$ mkdir Sources/sample/Resources 

3. Update the package.swift.

.target(
     name: "sample",
    exclude: ["Resources"], // Added
    resources: [.copy("Resources")] // Added
),

4. Run describe

$ swift package describe --type json 

Swift Package Manager version/commit hash

6.1.0

Swift & OS version (output of swift --version ; uname -a)

swift-driver version: 1.120.5 Apple Swift version 6.1 (swiftlang-6.1.0.109.103 clang-1700.0.13.2)
Target: arm64-apple-macosx15.0
Darwin matsujiMacBook-Pro.local 24.3.0 Darwin Kernel Version 24.3.0: Thu Jan  2 20:24:16 PST 2025; root:xnu-11215.81.4~3/RELEASE_ARM64_T6000 arm64

[plemarquand]

I've also seen this behaviour before. The VS Code Swift extension has a workaround for this which trims all output until the first line starting with {. As a short term workaround this might be helpful.

[mtj0928]

@plemarquand Thank you for sharing the workaround!
I adopted a similar workaround in my project.

https://github.com/mtj0928/nest/pull/31/files

[plemarquand]

@mtj0928 You'll likely want to tweak your workaround so it looks for the first line that starts with {, not the first instance of {, since brackets may appear somewhere in the warning output.