Add OPENATTRIBUTEGRAPH_LIB_SWIFT_PATH support

Package.swift

@@ -35,13 +35,21 @@ let isSPIBuild = envEnable("SPI_BUILD")
 let isXcodeEnv = Context.environment["__CFBundleIdentifier"] == "com.apple.dt.Xcode"
 let development = envEnable("OPENATTRIBUTEGRAPH_DEVELOPMENT", default: false)
 
-let swiftBinPath = Context.environment["_"] ?? "/usr/bin/swift"
-let swiftBinURL = URL(fileURLWithPath: swiftBinPath)
-let SDKPath = swiftBinURL.deletingLastPathComponent().deletingLastPathComponent().deletingLastPathComponent().path
-let includePath = SDKPath.appending("/usr/lib/swift")
+// From Swift toolchain being installed or from Swift SDK.
+func detectLibSwiftPath() -> String {
+    guard let libSwiftPath = Context.environment["OPENATTRIBUTEGRAPH_LIB_SWIFT_PATH"] else {
+        // Fallback when LIB_SWIFT_PATH is not set
+        let swiftBinPath = Context.environment["OPENATTRIBUTEGRAPH_BIN_SWIFT_PATH"] ?? Context.environment["_"] ?? "/usr/bin/swift"
+        let swiftBinURL = URL(fileURLWithPath: swiftBinPath)
+        let SDKPath = swiftBinURL.deletingLastPathComponent().deletingLastPathComponent().deletingLastPathComponent().path
+        return SDKPath.appending("/usr/lib/swift")
+    }
+    return libSwiftPath
+}
+let libSwiftPath = detectLibSwiftPath()
 
 var sharedCSettings: [CSetting] = [
-    .unsafeFlags(["-I", includePath], .when(platforms: .nonDarwinPlatforms)),
+    .unsafeFlags(["-I", libSwiftPath], .when(platforms: .nonDarwinPlatforms)),
     .define("NDEBUG", .when(configuration: .release)),
 ]
 

README.md

@@ -38,6 +38,7 @@ dependencies: [
 ```
 
 > [!NOTE]
+>
 > - You may need to configure the Swift toolchain header for proper integration of OpenAttributeGraph
 > - By default, OpenAttributeGraphShims will use the private AttributeGraph as its implementation on Apple platforms
 
@@ -49,6 +50,26 @@ For a simpler setup, you can use the prebuilt XCFramework available on the [rele
 
 The current suggested toolchain to build the project is Swift 6.1.2 / Xcode 16.4.
 
+### Set up LIB_SWIFT_PATH on non-Darwin platform
+
+If your swift binary path is located in your `<toolchain>/usr/bin/swift` (eg. installed by [swiftbox](https://github.com/stevapple/swiftbox)), no setup is required.
+
+Otherwise set up it manully by exporting `LIB_SWIFT_PATH` environment variable.
+
+> The following command assume you already have [swiftly](https://github.com/swiftlang/swiftly) installed.
+
+```shell
+export OPENATTRIBUTEGRAPH_LIB_SWIFT_PATH="$(swiftly use --print-location)/usr/lib/swift"
+# Or use the swift_static path
+export OPENATTRIBUTEGRAPH_LIB_SWIFT_PATH="$(swiftly use --print-location)/usr/lib/swift_static"
+```
+
+Alternatively, you can set the path using the Swift SDK location. For example:
+
+```shell
+export OPENATTRIBUTEGRAPH_LIB_SWIFT_PATH=~/.swiftpm/swift-sdks/swift-6.1.3-RELEASE_static-linux-0.0.1.artifactbundle/swift-6.1.3-RELEASE_static-linux-0.0.1/swift-linux-musl/musl-1.2.5.sdk/aarch64/usr/lib/swift_static
+```
+
 ## License
 
 See LICENSE file - MIT