Hard crash while parsing Wikipedia SVG

[vsameer]

Im building an Wikipedia client, have had good success with SwiftDraw, until when one of the link in article for "The Russian Empire" crashing the app consistent. The error is "Thread 10: EXC_BAD_ACCESS (code=2, address=0x16bf6bf70)" and it's thrown in following code in XMLParser/

mutating func scanString(upTo token: String) throws -> String {
            scanner.currentIndex = currentIndex
            guard let match = scanner.scanUpToString(token) else {
                throw Error.invalid
            }

            currentIndex = scanner.currentIndex
            return match
        }

Thanks

[swhitty]

Thank you for reporting this @vsameer.

I've had a look and this is basically a stack overflow issue because SwiftDraw uses recursion to parse the XML structure into a DOM. When using @MainActor you typically don't see the issue because Swift uses a larger stack but its far smaller when executing on the global concurrent executor (adding a single async causes this).

For the time being you can mark your function @MainActor and it should parse and render correctly — I will investigate using tail recursion for the parsing to avoid this issue.

[swhitty]

Fix is available in the 0.21.0 release