Fix Integer type serialization for 32-bit platforms

Motivation:

[RFC 9651](https://www.ietf.org/rfc/rfc9651.html) permits serializing an integer in the range of -999,999,999,999,999 to 999,999,999,999,999 inclusive ([Section 4.1.4-2.1.1](https://www.ietf.org/rfc/rfc9651.html#section-4.1.4-2.1.1)). As `RFC9651BareItem` takes values `integer` or `date` with an associated value of type `Int`, that range is implicitly more constrained on 32-bit platforms to a subset range of `-Int32.min` to `Int32.max` inclusive.

Modifications:

- Adjust `RFC9651BareItem` to take values `integer` or `date` with an associated value of type `Int64` instead, which is sufficient for the permitted range.

Result:

Compatibility for the Integer and Date Structured Types on 32-bit platforms.

Sources/RawStructuredFieldValues/ComponentTypes.swift

@@ -94,7 +94,7 @@ extension BareItem {
             self = .bool(b)
 
         case .integer(let i):
-            self = .integer(i)
+            self = .integer(Int(i))
 
         case .decimal(let d):
             self = .decimal(d)
@@ -126,7 +126,7 @@ public enum RFC9651BareItem: Sendable {
     case bool(Bool)
 
     /// An integer item.
-    case integer(Int)
+    case integer(Int64)
 
     /// A decimal item.
     case decimal(PseudoDecimal)
@@ -142,7 +142,7 @@ public enum RFC9651BareItem: Sendable {
     case token(String)
 
     /// A date item.
-    case date(Int)
+    case date(Int64)
 
     /// A display string item.
     case displayString(String)
@@ -155,7 +155,7 @@ extension RFC9651BareItem: ExpressibleByBooleanLiteral {
 }
 
 extension RFC9651BareItem: ExpressibleByIntegerLiteral {
-    public init(integerLiteral value: Int) {
+    public init(integerLiteral value: Int64) {
         self = .integer(value)
     }
 }
@@ -184,7 +184,7 @@ extension RFC9651BareItem {
             self = .bool(b)
 
         case .integer(let i):
-            self = .integer(i)
+            self = .integer(Int64(i))
 
         case .decimal(let d):
             self = .decimal(d)

Sources/RawStructuredFieldValues/FieldParser.swift

@@ -232,7 +232,7 @@ extension StructuredFieldValueParser {
     }
 
     private mutating func _parseAnIntegerOrDecimal(isDate: Bool) throws -> RFC9651BareItem {
-        var sign = 1
+        var sign = Int64(1)
         var type = IntegerOrDecimal.integer
 
         if let first = self.underlyingData.first, first == asciiDash {
@@ -304,7 +304,7 @@ extension StructuredFieldValueParser {
         case .integer:
             // This intermediate string is sad, we should rewrite this manually to avoid it.
             // This force-unwrap is safe, as we have validated that all characters are ascii digits.
-            let baseInt = Int(String(decoding: integerBytes, as: UTF8.self), radix: 10)!
+            let baseInt = Int64(String(decoding: integerBytes, as: UTF8.self), radix: 10)!
             let resultingInt = baseInt * sign
 
             if isDate {

Sources/StructuredFieldValues/Encoder/StructuredFieldValueEncoder.swift

@@ -313,7 +313,7 @@ extension _StructuredFieldEncoder: SingleValueEncodingContainer {
     }
 
     func encode(_ data: Date) throws {
-        let date = Int(data.timeIntervalSince1970)
+        let date = Int64(data.timeIntervalSince1970)
         try self.currentStackEntry.storage.insertBareItem(.date(date))
     }
 
@@ -371,7 +371,7 @@ extension _StructuredFieldEncoder: SingleValueEncodingContainer {
     }
 
     private func _encodeFixedWidthInteger<T: FixedWidthInteger>(_ value: T) throws {
-        guard let base = Int(exactly: value) else {
+        guard let base = Int64(exactly: value) else {
             throw StructuredHeaderError.integerOutOfRange
         }
         try self.currentStackEntry.storage.insertBareItem(.integer(base))
@@ -483,7 +483,7 @@ extension _StructuredFieldEncoder {
     }
 
     func append(_ value: Date) throws {
-        let date = Int(value.timeIntervalSince1970)
+        let date = Int64(value.timeIntervalSince1970)
         try self.currentStackEntry.storage.appendBareItem(.date(date))
     }
 
@@ -562,7 +562,7 @@ extension _StructuredFieldEncoder {
     }
 
     private func _appendFixedWidthInteger<T: FixedWidthInteger>(_ value: T) throws {
-        guard let base = Int(exactly: value) else {
+        guard let base = Int64(exactly: value) else {
             throw StructuredHeaderError.integerOutOfRange
         }
         try self.currentStackEntry.storage.appendBareItem(.integer(base))
@@ -667,7 +667,7 @@ extension _StructuredFieldEncoder {
 
     func encode(_ value: Date, forKey key: String) throws {
         let key = self.sanitizeKey(key)
-        let date = Int(value.timeIntervalSince1970)
+        let date = Int64(value.timeIntervalSince1970)
         try self.currentStackEntry.storage.insertBareItem(.date(date), atKey: key)
     }
 
@@ -789,7 +789,7 @@ extension _StructuredFieldEncoder {
     }
 
     private func _encodeFixedWidthInteger<T: FixedWidthInteger>(_ value: T, forKey key: String) throws {
-        guard let base = Int(exactly: value) else {
+        guard let base = Int64(exactly: value) else {
             throw StructuredHeaderError.integerOutOfRange
         }
         try self.currentStackEntry.storage.insertBareItem(.integer(base), atKey: key)

Tests/StructuredFieldValuesTests/Fixtures.swift

@@ -119,7 +119,7 @@ struct StructuredHeaderTestFixture: Decodable {
 enum JSONSchema: Decodable {
     case dictionary([String: JSONSchema])
     case array([JSONSchema])
-    case integer(Int)
+    case integer(Int64)
     case double(Double)
     case string(String)
     case bool(Bool)
@@ -130,7 +130,7 @@ enum JSONSchema: Decodable {
             self = .string(value)
         } else if let bool = try? container.decode(Bool.self) {
             self = .bool(bool)
-        } else if let value = try? container.decode(Int.self) {
+        } else if let value = try? container.decode(Int64.self) {
             self = .integer(value)
         } else if let value = try? container.decode(Double.self) {
             self = .double(value)