From d4ba61791111bdbc06b94e52decbd48f408f21a9 Mon Sep 17 00:00:00 2001
From: Tardis Xu <xiaoxubeii@gmail.com>
Date: Mon, 3 Sep 2018 23:59:17 +0800
Subject: [PATCH] clean: clean mod cache should respect "-n" option.

Clean mod cache should print remove commands and not run them when with set "-n" option.
Fixes #27458.
---
 src/cmd/go/internal/clean/clean.go | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/cmd/go/internal/clean/clean.go b/src/cmd/go/internal/clean/clean.go
index d023592eed..8773586a6f 100644
--- a/src/cmd/go/internal/clean/clean.go
+++ b/src/cmd/go/internal/clean/clean.go
@@ -112,9 +112,10 @@ func runClean(cmd *base.Command, args []string) {
 		}
 	}
 
+	var b work.Builder
+	b.Print = fmt.Print
+
 	if cleanCache {
-		var b work.Builder
-		b.Print = fmt.Print
 		dir := cache.DefaultDir()
 		if dir != "off" {
 			// Remove the cache subdirectories but not the top cache directory.
@@ -156,8 +157,13 @@ func runClean(cmd *base.Command, args []string) {
 		if modfetch.PkgMod == "" {
 			base.Fatalf("go clean -modcache: no module cache")
 		}
-		if err := removeAll(modfetch.PkgMod); err != nil {
-			base.Errorf("go clean -modcache: %v", err)
+		if cfg.BuildN || cfg.BuildX {
+			b.Showcmd("", "rm -r %s", modfetch.PkgMod)
+		}
+		if !cfg.BuildN {
+			if err := removeAll(modfetch.PkgMod); err != nil {
+				base.Errorf("go clean -modcache: %v", err)
+			}
 		}
 	}
 }