No way to discover a trait's Compilation Condition

[davedelong]

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

SwiftPM does not appear to provide any sort of in-editor information to a package developer about how to use traits defined in Package.swift. There's no indication informational message, no template comments, no autocomplete help, etc for what this .trait(...) thing does nor how one is supposed to use it. There is no autocomplete for #if ...

Expected behavior

No response

Actual behavior

No response

Steps to reproduce

No response

Swift Package Manager version/commit hash

Swift Package Manager - Swift 6.0.3

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

swift-driver version: 1.115.1 Apple Swift version 6.0.3 (swiftlang-6.0.3.1.9 clang-1600.0.30.1)

Darwin Localhost 24.3.0 Darwin Kernel Version 24.3.0: Thu Jan 2 20:24:23 PST 2025; root:xnu-11215.81.4~3/RELEASE_ARM64_T6020 arm64

[ahoppen]

Synced to Apple’s issue tracker as rdar://146864867

[ahoppen]

Just to make sure I understand you correctly: Are you suggesting that code completion should offer the available trait names when completing inside #if?

[davedelong]

Essentially, yes. If I type #if and then hit escape, I should be getting a list of possible things that can go after an #if token, which includes trait names. I should not be getting the current (as of Xcode 16.2) behavior of "No Completions".