Support "-nan" in TextFormat.

As odd as it sounds, upstream supports this and there is a unittest that ensure it parses: https://github.com/protocolbuffers/protobuf/blob/3c03e9351c57081d0dffae120ed37497017f105c/src/google/protobuf/compiler/parser_unittest.cc#L464 It seems to have come from: protocolbuffers/protobuf#15017 So make sure Swift is also able to parse it.
thomasvl · May 9, 2024 · 664524c · 664524c
1 parent a1ce4a0
commit 664524c
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Showing 3 changed files with 20 additions and 3 deletions.
diff --git a/Sources/SwiftProtobuf/TextFormatScanner.swift b/Sources/SwiftProtobuf/TextFormatScanner.swift
@@ -897,8 +897,18 @@ internal struct TextFormatScanner {
 
     // If the next token is the identifier "nan", return true.
     private mutating func skipOptionalNaN() -> Bool {
-        return skipOptionalKeyword(bytes:
-                                  [asciiLowerN, asciiLowerA, asciiLowerN])
+        let start = p
+        // "-nan" doesn't mean anything, but upstream handles it, so skip
+        // over any leading minus when checking for "nan".
+        if p != end && p[0] == asciiMinus {
+            p += 1
+        }
+        if skipOptionalKeyword(bytes: [asciiLowerN, asciiLowerA, asciiLowerN]) {
+            return true
+        } else {
+            p = start  // It wasn't "nan", rewind incase we skipped a minus sign.
+            return false
+        }
     }
 
     // If the next token is a recognized spelling of "infinity",
@@ -1311,7 +1321,7 @@ internal struct TextFormatScanner {
             }
         }
 
-        // This will also cover "true", "false" for booleans, "nan" for floats.
+        // This will also cover "true", "false" for booleans, "nan"/"inf" for floats.
         if let _ = try nextOptionalEnumName() {
             skipWhitespace()  // `nextOptionalEnumName()` doesn't skip trailing whitespace
             return

diff --git a/Sources/protoc-gen-swift/Descriptor+Extensions.swift b/Sources/protoc-gen-swift/Descriptor+Extensions.swift
@@ -352,13 +352,15 @@ extension FieldDescriptor {
         case "inf": return "Double.infinity"
         case "-inf": return "-Double.infinity"
         case "nan": return "Double.nan"
+        case "-nan": return "Double.nan"
         default: return defaultValue
         }
       case .float:
         switch defaultValue {
         case "inf": return "Float.infinity"
         case "-inf": return "-Float.infinity"
         case "nan": return "Float.nan"
+        case "-nan": return "Float.nan"
         default: return defaultValue
         }
       case .string:

diff --git a/Tests/SwiftProtobufTests/Test_TextFormatDecodingOptions.swift b/Tests/SwiftProtobufTests/Test_TextFormatDecodingOptions.swift
@@ -409,8 +409,13 @@ final class Test_TextFormatDecodingOptions: XCTestCase {
         assertDecodeIgnoringUnknownsSucceeds("double", "-1e-9999")
 
         assertDecodeIgnoringUnknownsSucceeds("float", "nan")
+        assertDecodeIgnoringUnknownsSucceeds("float", "-nan")
         assertDecodeIgnoringUnknownsSucceeds("float", "inf")
         assertDecodeIgnoringUnknownsSucceeds("float", "-inf")
+        assertDecodeIgnoringUnknownsSucceeds("double", "nan")
+        assertDecodeIgnoringUnknownsSucceeds("double", "-nan")
+        assertDecodeIgnoringUnknownsSucceeds("double", "inf")
+        assertDecodeIgnoringUnknownsSucceeds("double", "-inf")
     }
 
     func testIgnoreUnknown_Messages() {