SwiftFixIt: Require that locations are resolved in the right source file

Author: AnthonyLatsis

Sources/SwiftFixIt/SwiftFixit.swift

@@ -219,7 +219,12 @@ private struct SourceFile {
         )
     }
 
-    func position(of location: borrowing some AnySourceLocation) -> AbsolutePosition {
+    func position(of location: borrowing some AnySourceLocation) throws -> AbsolutePosition {
+        guard try AbsolutePath(validating: location.filename) == self.path else {
+            // Wrong source file.
+            throw Error.failedToResolveSourceLocation
+        }
+
         guard location.offset == 0 else {
             return AbsolutePosition(utf8Offset: Int(location.offset))
         }
@@ -231,7 +236,7 @@ private struct SourceFile {
     }
 
     func node(at location: some AnySourceLocation) throws -> Syntax {
-        let position = position(of: location)
+        let position = try position(of: location)
 
         if let token = syntax.token(at: position) {
             return SwiftSyntax.Syntax(token)
@@ -305,10 +310,10 @@ extension DiagnosticConverter {
     private static func fixIt(
         from diagnostic: borrowing some AnyDiagnostic,
         in sourceFile: borrowing SourceFile
-    ) -> SwiftDiagnostics.FixIt {
-        let changes = diagnostic.fixIts.map { fixIt in
-            let startPosition = sourceFile.position(of: fixIt.start)
-            let endPosition = sourceFile.position(of: fixIt.end)
+    ) throws -> SwiftDiagnostics.FixIt {
+        let changes = try diagnostic.fixIts.map { fixIt in
+            let startPosition = try sourceFile.position(of: fixIt.start)
+            let endPosition = try sourceFile.position(of: fixIt.end)
 
             return SwiftDiagnostics.FixIt.Change.replaceText(
                 range: startPosition ..< endPosition,
@@ -325,8 +330,8 @@ extension DiagnosticConverter {
         in sourceFile: borrowing SourceFile
     ) throws -> [Syntax] {
         try diagnostic.ranges.map { startLocation, endLocation in
-            let startPosition = sourceFile.position(of: startLocation)
-            let endPosition = sourceFile.position(of: endLocation)
+            let startPosition = try sourceFile.position(of: startLocation)
+            let endPosition = try sourceFile.position(of: endLocation)
 
             var highlightedNode = try sourceFile.node(at: startLocation)
 

Tests/SwiftFixItTests/SwiftFixItTests.swift

@@ -549,31 +549,35 @@ extension SwiftFixItTests {
         }
     }
 
-    func testFixItInDifferentFile() throws {
-        XCTExpectFailure()
-
-        // Apply a fix-it in a different file.
-        try self.testAPI { (filename1: String, filename2: String) in
-            (
-                sourceFileEdits: (
-                    .init(input: "var x = 1", result: "let x = 1"),
-                    .init(input: "", result: "")
-                ),
-                diagnostics: [
-                    TestDiagnostic(
-                        text: "error",
-                        level: .error,
-                        location: .init(filename: filename2, line: 1, column: 1, offset: 0),
-                        fixIts: [
-                            .init(
-                                start: .init(filename: filename1, line: 1, column: 1, offset: 0),
-                                end: .init(filename: filename1, line: 1, column: 4, offset: 0),
-                                text: "let"
-                            ),
-                        ]
+    func testFixItInDifferentFile() {
+        do {
+            try self.testAPI { (filename1: String, filename2: String) in
+                (
+                    sourceFileEdits: (
+                        .init(input: "var x = 1", result: "let x = 1"),
+                        .init(input: "", result: "")
                     ),
-                ]
-            )
+                    diagnostics: [
+                        TestDiagnostic(
+                            text: "error",
+                            level: .error,
+                            location: .init(filename: filename2, line: 1, column: 1, offset: 0),
+                            fixIts: [
+                                .init(
+                                    start: .init(filename: filename1, line: 1, column: 1, offset: 0),
+                                    end: .init(filename: filename1, line: 1, column: 4, offset: 0),
+                                    text: "let"
+                                ),
+                            ]
+                        ),
+                    ]
+                )
+            }
+        } catch {
+            // Expected to throw an error.
+            return
         }
+
+        XCTFail()
     }
 }