FixItApplier crash when generating diagnostics for whole tree but applying them to a subtree #2749
Description
Description
The crash:
Steps to Reproduce
Note that @Enumerator() does not modify the code at all in this case.
I'm just sharing the exact code otherwise I think this should be reproducible not that hard.
Late night here, if I were to wait till tomorrow I'm pretty sure I would have ended up not reporting this bug, let me know if reproducing this doesn't end up being easy.
The exact code:
func testAppliesFixIts() { let unterminatedString = """ let unterminated = ℹ️"This is unterminated1️⃣ """ assertMacroExpansion( #""" @Enumerator(""" \#(unterminatedString) """) enum TestEnum { case a(val1: String, Int) case b case testCase(testValue: String) } """#, expandedSource: #""" enum TestEnum { case a(val1: String, Int) case b case testCase(testValue: String) let unterminated = "This is unterminated" } """#, macros: EnumeratorMacroEntryPoint.macros ) }How FixIts are applied in the pipeline of the macro:
var statement = statement var diagnostics = ParseDiagnosticsGenerator.diagnostics(for: statement) /// Returns if anything changed at all. func tryApplyFixIts() -> Bool { guard diagnostics.contains(where: { !$0.fixIts.isEmpty }) else { return false } let fixedStatement = FixItApplier.applyFixes( from: diagnostics, filterByMessages: nil, to: statement ) var parser = Parser(fixedStatement) let newStatement = CodeBlockItemSyntax.parse(from: &parser) guard statement != newStatement else { return false } let placeholderDetector = PlaceholderDetector() placeholderDetector.walk(newStatement) /// One of the FixIts added a placeholder, so the fixes are unacceptable /// Known behavior which is fine for now: even if one FixIt is /// misbehaving, still none of the FixIts will be applied. if placeholderDetector.containedPlaceholder { return false } else { statement = newStatement return true } } final class PlaceholderDetector: SyntaxVisitor { var containedPlaceholder = false override init(viewMode: SyntaxTreeViewMode = .sourceAccurate) { super.init(viewMode: viewMode) } override func visit(_ node: TokenSyntax) -> SyntaxVisitorContinueKind { if node.isEditorPlaceholder { self.containedPlaceholder = true return .skipChildren } return .visitChildren } }Edit: Added PlaceholderDetector for the sake of being complete, although it doesn't matter.