fix: only add dependency when unresolved (#749)

bzlmod/workspace/Sources/MyExecutable/MyExecutable.swift

@@ -3,12 +3,21 @@ import Logging
 import MyLibrary
 import RegexBuilder
 
+// Because we build on macos/linux this needs to be conditionally imported to test an edge case
+#if canImport(os)
+import os
+#endif
+
 @main
 struct MyExecutable: AsyncParsableCommand {
     struct Plugin { }
     mutating func run() async throws {
         let output = "Hello, \(World().name)!"
         let logger = Logger(label: "com.example.BestExampleApp.main")
         logger.info("\(output)")
+
+        #if canImport(os)
+        os_log("This is a debug message.", log: OSLog.default, type: .debug)
+        #endif
     }
 }

gazelle/internal/swift/dependency_index.go

@@ -275,8 +275,15 @@ func (di *DependencyIndex) ResolveModulesToProducts(
 		}
 		sort.Sort(sort.Reverse(psrs))
 		selectedPsr := psrs[0]
-		selectedPiks = append(selectedPiks, selectedPsr.pik)
-		modulesToResolve = modulesToResolve.Difference(selectedPsr.intersect)
+
+		if selectedPsr.intersectCnt > 0 {
+			// We found a product that contains at least one of the modules that we are trying to
+			// resolve. Add it to the list of selected products and remove the modules that it
+			// contains from the list of modules that we are trying to resolve.
+			selectedPiks = append(selectedPiks, selectedPsr.pik)
+			modulesToResolve = modulesToResolve.Difference(selectedPsr.intersect)
+		}
+
 		potentialPikSet.Remove(selectedPsr.pik)
 	}