Disable copyFrom when using a Swift <6 compiler

Swift 5.10 does not support `#isolation`, which we use.

Author: ahoppen

Sources/PostgresNIO/Connection/PostgresConnection+CopyFrom.swift

@@ -29,6 +29,7 @@ public struct PostgresCopyFromWriter: Sendable {
         }
     }
 
+    #if compiler(>=6.0)
     /// Send data for a `COPY ... FROM STDIN` operation to the backend.
     ///
     /// - Throws: If an error occurs during the write of if the backend sent an `ErrorResponse` during the copy 
@@ -96,6 +97,7 @@ public struct PostgresCopyFromWriter: Sendable {
             }
         }
     }
+    #endif
 }
 
 /// Specifies the format in which data is transferred to the backend in a COPY operation.
@@ -124,6 +126,7 @@ public struct PostgresCopyFromFormat: Sendable {
     }
 }
 
+#if compiler(>=6.0)
 /// Create a `COPY ... FROM STDIN` query based on the given parameters.
 ///
 /// An empty `columns` array signifies that no columns should be specified in the query and that all columns will be
@@ -221,3 +224,4 @@ extension PostgresConnection {
         try await writer.done()
     }
 }
+#endif

Tests/IntegrationTests/PSQLIntegrationTests.swift

@@ -379,6 +379,7 @@ final class IntegrationTests: XCTestCase {
         }
     }
 
+    #if compiler(>=6.0)
     func testCopyIntoFrom() async throws {
         let eventLoopGroup = MultiThreadedEventLoopGroup(numberOfThreads: 2)
         defer { XCTAssertNoThrow(try eventLoopGroup.syncShutdownGracefully()) }
@@ -487,4 +488,5 @@ final class IntegrationTests: XCTestCase {
             XCTAssertEqual((error as? PSQLError)?.serverInfo?[.sqlState], "42601") // scanner_yyerror
         }
     }
+    #endif
 }

Tests/PostgresNIOTests/New/PostgresConnectionTests.swift

@@ -625,6 +625,7 @@ class PostgresConnectionTests: XCTestCase {
         }
     }
 
+    #if compiler(>=6.0)
     func testCopyFromSucceeds() async throws {
         try await assertCopyFrom { writer in
             try await writer.write(ByteBuffer(staticString: "1\tAlice\n"))
@@ -911,6 +912,7 @@ class PostgresConnectionTests: XCTestCase {
             try await connection.closeFuture.get()
         }
     }
+    #endif
 
     func makeTestConnectionWithAsyncTestingChannel() async throws -> (PostgresConnection, NIOAsyncTestingChannel) {
         let eventLoop = NIOAsyncTestingEventLoop()
@@ -944,6 +946,7 @@ class PostgresConnectionTests: XCTestCase {
         return (connection, channel)
     }
 
+    #if compiler(>=6.0)
     /// Validate the behavior of a `COPY FROM` query.
     ///
     /// Also checks that the connection returns to an idle state after performing the copy and is capable
@@ -1011,6 +1014,7 @@ class PostgresConnectionTests: XCTestCase {
             _ = try await channel.waitForUnpreparedRequest() // Await the dummy query messages
         }
     }
+    #endif
 }
 
 extension NIOAsyncTestingChannel {