From 1dfd70e0ab7bd5d5baa65e6675a6380bc9b33309 Mon Sep 17 00:00:00 2001
From: Rebecca Stambler <rstambler@golang.org>
Date: Fri, 4 Dec 2020 16:21:12 -0500
Subject: [PATCH] internal/imports: prevent panic in imports GOMODCACHE logic

Fixes golang/go#42949

Change-Id: Icabfce85550cb6e69383ba50c2c675a5c730bec5
Reviewed-on: https://go-review.googlesource.com/c/tools/+/275451
Trust: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
---
 internal/imports/mod.go | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/internal/imports/mod.go b/internal/imports/mod.go
index 73f7a49587..ce3269a430 100644
--- a/internal/imports/mod.go
+++ b/internal/imports/mod.go
@@ -88,7 +88,11 @@ func (r *ModuleResolver) init() error {
 	if gmc := r.env.Env["GOMODCACHE"]; gmc != "" {
 		r.moduleCacheDir = gmc
 	} else {
-		r.moduleCacheDir = filepath.Join(filepath.SplitList(goenv["GOPATH"])[0], "/pkg/mod")
+		gopaths := filepath.SplitList(goenv["GOPATH"])
+		if len(gopaths) == 0 {
+			return fmt.Errorf("empty GOPATH")
+		}
+		r.moduleCacheDir = filepath.Join(gopaths[0], "/pkg/mod")
 	}
 
 	sort.Slice(r.modsByModPath, func(i, j int) bool {