Add labels to tasks (#45)

vendor/honnef.co/go/tools/functions/terminates.go

@@ -0,0 +1,24 @@
+package functions
+
+import "honnef.co/go/tools/ssa"
+
+// terminates reports whether fn is supposed to return, that is if it
+// has at least one theoretic path that returns from the function.
+// Explicit panics do not count as terminating.
+func terminates(fn *ssa.Function) bool {
+	if fn.Blocks == nil {
+		// assuming that a function terminates is the conservative
+		// choice
+		return true
+	}
+
+	for _, block := range fn.Blocks {
+		if len(block.Instrs) == 0 {
+			continue
+		}
+		if _, ok := block.Instrs[len(block.Instrs)-1].(*ssa.Return); ok {
+			return true
+		}
+	}
+	return false
+}