Following this tutorial generates a compile error on swift 5.9

[DeCarabas]

When I follow this tutorial, after entering the code in the step entitled "A small application", running swift run MyCLI gives me the following errors:

C:\src\misc\MyCLI>swift run MyCLI
Building for debugging...
error: emit-module command failed with exit code 1 (use -v to see invocation)
C:\src\misc\MyCLI\Sources\MyCLI.swift:3:1: error: 'main' attribute cannot be used in a module that contains top-level code
@main
^
C:\src\misc\MyCLI\Sources\MyCLI.swift:1:1: note: top-level code defined in this source file
import Figlet
^
C:\src\misc\MyCLI\Sources\MyCLI.swift:1:1: note: pass '-parse-as-library' to compiler invocation if this is intentional
import Figlet
^
C:\src\misc\MyCLI\Sources\MyCLI.swift:3:1: error: 'main' attribute cannot be used in a module that contains top-level code
@main
^
C:\src\misc\MyCLI\Sources\MyCLI.swift:1:1: note: top-level code defined in this source file
import Figlet
^
C:\src\misc\MyCLI\Sources\MyCLI.swift:1:1: note: pass '-parse-as-library' to compiler invocation if this is intentional
import Figlet
^
error: fatalError

Here's what my files and whatnot look like:

C:\src\misc\MyCLI>swift --version
Swift version 5.9.1 (swift-5.9.1-RELEASE)
Target: x86_64-unknown-windows-msvc

C:\src\misc\MyCLI>cat Package.swift
// swift-tools-version: 5.9
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
  name: "MyCLI",
  dependencies: [
    .package(url: "https://github.com/apple/example-package-figlet", branch:"main"),
  ],
  targets: [
    // Targets are the basic building blocks of a package, defining a module or a test suite.
    // Targets can depend on other targets in this package and products from dependencies.
    .executableTarget(
      name: "MyCLI",
      dependencies: [
        .product(name: "Figlet", package: "example-package-figlet"),
      ],
      path: "Sources"),
  ]
)

C:\src\misc\MyCLI>dir Sources
 Volume in drive C is Primary
 Volume Serial Number is 869D-696D

 Directory of C:\src\misc\MyCLI\Sources

11/19/2023  11:11 AM    <DIR>          .
11/19/2023  11:03 AM    <DIR>          ..
11/19/2023  11:04 AM               118 MyCLI.swift
               1 File(s)            118 bytes
               2 Dir(s)  251,722,711,040 bytes free

C:\src\misc\MyCLI>cat Sources\MyCLI.swift
import Figlet

@main
struct FigletTool {
    static func main() {
        Figlet.say("Hello, Swift!")
    }
}

This looks like it might be related to swiftlang/swift#55127; indeed, when I create an empty file next to MyCLI.swift the project runs correctly:

C:\src\misc\MyCLI>touch Sources\empty.swift

C:\src\misc\MyCLI>dir Sources
 Volume in drive C is Primary
 Volume Serial Number is 869D-696D

 Directory of C:\src\misc\MyCLI\Sources

11/19/2023  11:15 AM    <DIR>          .
11/19/2023  11:03 AM    <DIR>          ..
11/19/2023  11:15 AM                 0 empty.swift
11/19/2023  11:04 AM               118 MyCLI.swift
               2 File(s)            118 bytes
               2 Dir(s)  251,721,732,096 bytes free

C:\src\misc\MyCLI>swift run MyCLI
Building for debugging...
lld-link: warning: C:\src\misc\MyCLI\.build\x86_64-unknown-windows-msvc\debug\MyCLI.build\MyCLI.swift.o: locally defined symbol imported: $s6FigletAAO3sayyySSFZ (defined in C:\src\misc\MyCLI\.build\x86_64-unknown-windows-msvc\debug\Figlet.build\Figlet.swift.o) [LNK4217]
[5/5] Linking C:\src\misc\MyCLI\.build\x86_64-unknown-windows-msvc\debug\MyCLI.exe
Build complete! (1.30s)
  _   _          _   _                 ____               _    __   _     _
 | | | |   ___  | | | |   ___         / ___|  __      __ (_)  / _| | |_  | |
 | |_| |  / _ \ | | | |  / _ \        \___ \  \ \ /\ / / | | | |_  | __| | |
 |  _  | |  __/ | | | | | (_) |  _     ___) |  \ V  V /  | | |  _| | |_  |_|
 |_| |_|  \___| |_| |_|  \___/  ( )   |____/    \_/\_/   |_| |_|    \__| (_)
                                |/

Ideally the swift bug would be fixed, but it looks like it's been open since 2020, so at least the tutorial should be fixed to work around this problem?

[0xTim]

Yeah this is a definite Swift bug on Windows - I'll raise it with some people to see if this can get some eyes or whether it's worth adding a note about Windows