Prebuilt binaries are .a's on Windows, not .lib's

[tristanlabelle]

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 new --enable-experimental-prebuilts support relies on downloading prebuilt libraries from swiftlang.org. The Windows version of these artifacts include .a library files, which is nonstandard on Windows and incompatible with link.exe.

Expected behavior

The file should be a .lib archive, for compatibility with link.exe and lld-link.exe, or both .a and .lib should be provided.

Actual behavior

The file found is a .a archive, libMacroSupport.a in this case.

Steps to reproduce

1. Download a prebuilt binary zip for Windows such as https://download.swift.org/prebuilts/swift-syntax/601.0.1/6.1-MacroSupport-windows_x86_64.zip
2. Open the zip and look for the library file under /lib

Swift Package Manager version/commit hash

N/A

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

Swift 6.1 for Windows

[dschaefer2]

Was worried about that and surprised lld-link.exe was happy with the .a's. Should be simple to fix.