cmd/go: avoid panic on 'go mod' without arguments

Fixes #26738

Change-Id: Icede3f59acb5b0e388660653cefc24a195b5d43b
GitHub-Last-Rev: 9989b74c12e94163c1f18859485a4ac0d74c5453
GitHub-Pull-Request: golang/go#26739
Reviewed-on: https://go-review.googlesource.com/127160
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

diff --git a/src/cmd/go/main.go b/src/cmd/go/main.go
index 25dfe8ffa4c9574b5092fee8b1c12f5ebaee3006..59d367edaaf712afaddc8806f5063129a5c9f2a2 100644 (file)
--- a/src/cmd/go/main.go
+++ b/src/cmd/go/main.go
@@ -193,6 +193,8 @@ BigCmdLoop:
                                args = args[1:]
                                if len(args) == 0 {
                                        help.PrintUsage(os.Stderr, bigCmd)
+                                       base.SetExitStatus(2)
+                                       base.Exit()
                                }
                                if args[0] == "help" {
                                        // Accept 'go mod help' and 'go mod help foo' for 'go help mod' and 'go help mod foo'.