Deserialize diagnostics with no location correctly

Author: owenv

Sources/TSCUtility/SerializedDiagnostics.swift

@@ -185,7 +185,7 @@ extension SerializedDiagnostics {
 
   public struct SourceLocation: Equatable {
     /// The filename associated with the diagnostic.
-    public var filename: String
+    public var filename: String?
     public var line: UInt64
     public var column: UInt64
     /// The byte offset in the source file of the diagnostic. Currently, only
@@ -194,10 +194,7 @@ extension SerializedDiagnostics {
 
     fileprivate init(fields: ArraySlice<UInt64>,
                      filenameMap: [UInt64: String]) throws {
-      guard let name = filenameMap[fields[fields.startIndex]] else {
-        throw Error.missingInformation
-      }
-      self.filename = name
+      self.filename = filenameMap[fields[fields.startIndex]]
       self.line = fields[fields.startIndex + 1]
       self.column = fields[fields.startIndex + 2]
       self.offset = fields[fields.startIndex + 3]

Tests/TSCUtilityTests/Inputs/no-location.dia

@@ -26,7 +26,7 @@ final class SerializedDiagnosticsTests: XCTestCase {
     let one = serializedDiags.diagnostics[5]
     XCTAssertEqual(one.text, "expected ',' separator")
     XCTAssertEqual(one.level, .error)
-    XCTAssertTrue(one.location.filename.hasSuffix("/StoreSearchCoordinator.swift"))
+    XCTAssertEqual(one.location.filename?.hasSuffix("/StoreSearchCoordinator.swift"), true)
     XCTAssertEqual(one.location.line, 21)
     XCTAssertEqual(one.location.column, 69)
     XCTAssertEqual(one.location.offset, 0)
@@ -36,32 +36,54 @@ final class SerializedDiagnosticsTests: XCTestCase {
     XCTAssertEqual(one.fixIts.count, 1)
     XCTAssertEqual(one.fixIts[0].text, ",")
     XCTAssertEqual(one.fixIts[0].start, one.fixIts[0].end)
-    XCTAssertTrue(one.fixIts[0].start.filename.hasSuffix("/StoreSearchCoordinator.swift"))
+    XCTAssertEqual(one.fixIts[0].start.filename?.hasSuffix("/StoreSearchCoordinator.swift"), true)
     XCTAssertEqual(one.fixIts[0].start.line, 21)
     XCTAssertEqual(one.fixIts[0].start.column, 69)
     XCTAssertEqual(one.fixIts[0].start.offset, 0)
 
     let two = serializedDiags.diagnostics[16]
     XCTAssertEqual(two.text, "use of unresolved identifier 'DispatchQueue'")
     XCTAssertEqual(two.level, .error)
-    XCTAssertTrue(two.location.filename.hasSuffix("/Observable.swift"))
+    XCTAssertEqual(two.location.filename?.hasSuffix("/Observable.swift"), true)
     XCTAssertEqual(two.location.line, 34)
     XCTAssertEqual(two.location.column, 13)
     XCTAssertEqual(two.location.offset, 0)
     XCTAssertNil(two.category)
     XCTAssertNil(two.flag)
     XCTAssertEqual(two.ranges.count, 1)
-    XCTAssertTrue(two.ranges[0].0.filename.hasSuffix("/Observable.swift"))
+    XCTAssertEqual(two.ranges[0].0.filename?.hasSuffix("/Observable.swift"), true)
     XCTAssertEqual(two.ranges[0].0.line, 34)
     XCTAssertEqual(two.ranges[0].0.column, 13)
     XCTAssertEqual(two.ranges[0].0.offset, 0)
-    XCTAssertTrue(two.ranges[0].1.filename.hasSuffix("/Observable.swift"))
+    XCTAssertEqual(two.ranges[0].1.filename?.hasSuffix("/Observable.swift"), true)
     XCTAssertEqual(two.ranges[0].1.line, 34)
     XCTAssertEqual(two.ranges[0].1.column, 26)
     XCTAssertEqual(two.ranges[0].1.offset, 0)
     XCTAssertEqual(two.fixIts.count, 0)
   }
 
+  func testReadDiagsWithNoLocation() throws {
+    let serializedDiagnosticsPath = AbsolutePath(#file).parentDirectory
+        .appending(components: "Inputs", "no-location.dia")
+    let contents = try localFileSystem.readFileContents(serializedDiagnosticsPath)
+    let serializedDiags = try SerializedDiagnostics(bytes: contents)
+
+    XCTAssertEqual(serializedDiags.versionNumber, 2)
+    XCTAssertEqual(serializedDiags.diagnostics.count, 1)
+
+    let diag = serializedDiags.diagnostics[0]
+    XCTAssertEqual(diag.text, "API breakage: func foo() has been removed")
+    XCTAssertEqual(diag.level, .error)
+    XCTAssertNil(diag.location.filename)
+    XCTAssertEqual(diag.location.line, 0)
+    XCTAssertEqual(diag.location.column, 0)
+    XCTAssertEqual(diag.location.offset, 0)
+    XCTAssertEqual(diag.category, "api-digester-breaking-change")
+    XCTAssertNil(diag.flag)
+    XCTAssertEqual(diag.ranges.count, 0)
+    XCTAssertEqual(diag.fixIts.count, 0)
+  }
+
   func testReadClangSerializedDiags() throws {
     let serializedDiagnosticsPath = AbsolutePath(#file).parentDirectory
         .appending(components: "Inputs", "clang.dia")