Add --trace-need

main.go

@@ -40,6 +40,7 @@ type DebugOptions struct {
 	TraceFile bool   `long:"trace-file"`
 	TraceNet  bool   `long:"trace-net"`
 	TraceIdx  bool   `long:"trace-idx"`
+	TraceNeed bool   `long:"trace-need"`
 	Profiler  string `long:"profiler" value-name:"ADDR"`
 }
 

model.go

@@ -447,6 +447,9 @@ func (m *Model) recomputeNeed() {
 				// Don't have the file, so don't need to delete it
 				continue
 			}
+			if opts.Debug.TraceNeed {
+				debugln("NEED:", ok, hf, f)
+			}
 			m.need[n] = true
 		}
 	}