Show a “pretty path” for outputs

So newcomers can find their products.

Author: mxcl

Sources/Build/describe().swift

@@ -244,7 +244,7 @@ public func describe(prefix: String, _ conf: Configuration, _ modules: [Module],
         let inputs = product.modules.flatMap{ [$0.targetName] + IncrementalNode(module: $0, prefix: prefix).inputs }
 
         let shell = ShellTool(
-            description: "Linking \(product)",
+            description: "Linking \(outpath.prettyPath)",
             inputs: inputs,
             outputs: [product.targetName, outpath],
             args: args)

Sources/Utility/Path.swift

@@ -269,4 +269,20 @@ extension String {
         let cleaned = characters.split(separator: "/").map(String.init).joined(separator: "/")
         return abs ? "/\(cleaned)" : cleaned
     }
+
+    /**
+      - Returns: A path suitable for display to the user, if possible,
+        a path relative to the current working directory.
+      - Note: As such this function relies on the working directory
+        not changing during execution.
+     */
+    public var prettyPath: String {
+        if let wd = try? getcwd() {
+            return Path(self).relative(to: wd)
+        } else if let abspath = try? abspath() {
+            return abspath
+        } else {
+            return self
+        }
+    }
 }