Explicitly add FoundationSupport trait

Author: Joannis

.github/workflows/test.yml

@@ -122,24 +122,21 @@ jobs:
           let package = Package(
             name: "DownstreamTestNoNIO",
             dependencies: [
-              .package(path: "../IkigaJSON"),
+              .package(path: "../IkigaJSON", traits: ["FoundationSupport"]),
             ],
             targets: [
               .executableTarget(
                 name: "DownstreamTestNoNIO",
                 dependencies: [
-                  .product(
-                    name: "IkigaJSON",
-                    package: "IkigaJSON",
-                    traits: ["FoundationSupport"]
-                  ),
+                  .product(name: "IkigaJSON", package: "IkigaJSON"),
                 ]
               )
             ]
           )
           PKGEOF
           mkdir -p downstream-test-no-nio/Sources/DownstreamTestNoNIO
           cat > downstream-test-no-nio/Sources/DownstreamTestNoNIO/main.swift << 'SRCEOF'
+          import Foundation
           import IkigaJSON
 
           struct Point: Decodable { let x: Int; let y: Int }

Package.swift

@@ -21,6 +21,9 @@ let package = Package(
       targets: ["_JSONCore"]
     ),
   ],
+  traits: [
+    .trait(name: "FoundationSupport", enabledTraits: [])
+  ],
   dependencies: [
     // Dependencies declare other packages that this package depends on.
     .package(url: "https://github.com/apple/swift-nio.git", from: "2.0.0")
@@ -38,17 +41,20 @@ let package = Package(
     .target(
       name: "_NIOJSON",
       dependencies: [
-        .product(name: "NIOCore", package: "swift-nio"),
-        .product(name: "NIOFoundationCompat", package: "swift-nio"),
+        .product(name: "NIOCore", package: "swift-nio", condition: .when(traits: ["FoundationSupport"])),
+        .product(name: "NIOFoundationCompat", package: "swift-nio", condition: .when(traits: ["FoundationSupport"])),
         .target(name: "_JSONCore"),
       ]
     ),
     .target(
       name: "IkigaJSON",
       dependencies: [
-        .product(name: "NIOCore", package: "swift-nio"),
+        .product(name: "NIOCore", package: "swift-nio", condition: .when(traits: ["FoundationSupport"])),
         .target(name: "_JSONCore"),
-        .target(name: "_NIOJSON"),
+        .target(name: "_NIOJSON", condition: .when(traits: ["FoundationSupport"])),
+      ],
+      swiftSettings: [
+        .define("FOUNDATION_SUPPORT", .when(traits: ["FoundationSupport"])),
       ]
     ),
     .testTarget(

Sources/IkigaJSON/Exports.swift

@@ -1 +1,5 @@
+#if FOUNDATION_SUPPORT
 @_exported import _NIOJSON
+#else
+@_exported import _JSONCore
+#endif