Use __BundleLookupHelper.self when building mergable library (#1389)

Co-authored-by: Andreas Neusuess <[email protected]>

Author: Tantalum73

Sources/FoundationMacros/BundleMacro.swift

@@ -22,6 +22,8 @@ public struct BundleMacro: SwiftSyntaxMacros.ExpressionMacro, Sendable {
                 return Bundle.module
             #elseif SWIFT_MODULE_RESOURCE_BUNDLE_UNAVAILABLE
                 #error("No resource bundle is available for this module. If resources are included elsewhere, specify the bundle manually.")
+            #elseif SWIFT_BUNDLE_LOOKUP_HELPER_AVAILABLE
+                return Bundle(for: __BundleLookupHelper.self)
             #else
                 return Bundle(_dsoHandle: #dsohandle) ?? .main
             #endif

Tests/FoundationMacrosTests/BundleMacroTests.swift

@@ -28,6 +28,8 @@ private struct BundleMacroTests {
                     return Bundle.module
                 #elseif SWIFT_MODULE_RESOURCE_BUNDLE_UNAVAILABLE
                     #error("No resource bundle is available for this module. If resources are included elsewhere, specify the bundle manually.")
+                #elseif SWIFT_BUNDLE_LOOKUP_HELPER_AVAILABLE
+                    return Bundle(for: __BundleLookupHelper.self)
                 #else
                     return Bundle(_dsoHandle: #dsohandle) ?? .main
                 #endif
@@ -48,6 +50,8 @@ private struct BundleMacroTests {
                     return Bundle.module
                 #elseif SWIFT_MODULE_RESOURCE_BUNDLE_UNAVAILABLE
                     #error("No resource bundle is available for this module. If resources are included elsewhere, specify the bundle manually.")
+                #elseif SWIFT_BUNDLE_LOOKUP_HELPER_AVAILABLE
+                    return Bundle(for: __BundleLookupHelper.self)
                 #else
                     return Bundle(_dsoHandle: #dsohandle) ?? .main
                 #endif