filePathMode: .filePath breaks macro expansion on Windows

[stefanspringer1]

Description

From my forums forums topic https://forums.swift.org/t/macro-expansion-failing-involving-sourcelocation/83250:

The code I used at one place is:

context.location(
    of: declaration.body!.statements,
    at: .beforeLeadingTrivia,
    filePathMode: .filePath
)

The file path on Windows involves backslashes, I am guessing that this leads to the file path being written as #"..."# in the outer macro expansion which in turn leads to the described error. The compilation errors in the above package (you have to build including the tests: swift build --build-tests) are absent if I use the following code (with .fileID instead of .filePath):

context.location(
    of: declaration.body!.statements,
    at: .beforeLeadingTrivia,
    filePathMode: .fileID
)

But with .fileID the relocation of errors does not work, so the .filePath seems to be needed and a correction of the described problem is important.

Steps to Reproduce

1. Check out https://github.com/stefanspringer1/Pipeline.git at commit number a8445b6ac3b5ecb8185647528ba4ce96e6784247 (tag: 1.0.12).
2. Building including the tests (swift build --build-test) is successful on macOS
3. Building including the tests on Windows results in the errors

macro expansion @Step:3:5: error: '#sourceLocation' cannot be an extended escaping string literal
...
macro expansion @Step:10:5: error: parameterless closing #sourceLocation() directive without prior opening #sourceLocation(file:,line:) directive
...

Environment

• Swift 6.2.1 on Windows (x86_64 and ARM) and macOS.
• swift-syntax 602.0.0.

[stefanspringer1]

I added in my code:

fileprivate extension AbstractSourceLocation {
    var fileWithCorrectedStringRepresentation: ExprSyntax {
        var filePath = "\(file)"
        if filePath.contains(/^#+.*"#+$/) {
            filePath.replace(/^#+"/, with: "")
            filePath.replace(/"#+$/, with: "")
            filePath.replace(#"\"#, with: #"\\"#)
            filePath.replace("\"", with: #"\""#)
            return "\(raw: "\"\(filePath)\"")"
        } else {
            return file
        }
    }
}

And instead of

var block = CodeBlockItemListSyntax {
    "#sourceLocation(file: \(location.file), line: \(line))"
    "\(node)"
}

I now use

var block = CodeBlockItemListSyntax {
    "#sourceLocation(file: \(location.fileWithCorrectedStringRepresentation), line: \(line))"
    "\(node)"
}

So a Windows path with backslashes will be represented as e.g. "C:\\mypath" instead of #"C:\mypath"#.

But I think that should be resolved in Swift Syntax, the path "C:\\mypath" is what actually should be used (note: my implementation above may not be perfect).

[rintaro]

Moved to swift because error: '#sourceLocation' cannot be an extended escaping string literal is from the compiler.