From 6b5bd55e173d96f7020a7b31dea21f7816b0c5c6 Mon Sep 17 00:00:00 2001
From: Rebecca Stambler <rstambler@golang.org>
Date: Mon, 16 Dec 2019 17:04:30 -0500
Subject: [PATCH 1/2] delete and recreate go.mod instead of running go mod tidy

---
 src/goInstallTools.ts | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/src/goInstallTools.ts b/src/goInstallTools.ts
index ddfec933b..01345ea75 100644
--- a/src/goInstallTools.ts
+++ b/src/goInstallTools.ts
@@ -134,10 +134,6 @@ export function installTools(missing: Tool[], goVersion: GoVersion): Promise<voi
 	// Install tools in a temporary directory, to avoid altering go.mod files.
 	const toolsTmpDir = fs.mkdtempSync(getTempFilePath('go-tools-'));
 
-	// Write a temporary go.mod file.
-	const tmpGoModFile = path.join(toolsTmpDir, 'go.mod');
-	fs.writeFileSync(tmpGoModFile, 'module tools');
-
 	return missing.reduce((res: Promise<string[]>, tool: Tool) => {
 		// Disable modules for tools which are installed with the "..." wildcard.
 		// TODO: ... will be supported in Go 1.13, so enable these tools to use modules then.
@@ -148,16 +144,19 @@ export function installTools(missing: Tool[], goVersion: GoVersion): Promise<voi
 			envForTools['GO111MODULE'] = 'on';
 		}
 
+		// Write a temporary go.mod file. This shouldn't affect anything if we've explicitly disabled modules.
+		const tmpGoModFile = path.join(toolsTmpDir, 'go.mod');
+		fs.writeFileSync(tmpGoModFile, 'module tools');
+
 		return res.then(sofar => new Promise<string[]>((resolve, reject) => {
 			const opts = {
 				env: envForTools,
 				cwd: toolsTmpDir,
 			};
 			const callback = (err: Error, stdout: string, stderr: string) => {
-				// Make sure to run `go mod tidy` between tool installations.
-				// This avoids us having to create a fresh go.mod file for each tool.
-				if (!modulesOffForTool) {
-					cp.execFileSync(goRuntimePath, ['mod', 'tidy'], opts);
+				// Make sure to delete the temporary go.mod file, if it exists.
+				if (fs.existsSync(tmpGoModFile)) {
+					fs.unlinkSync(tmpGoModFile);
 				}
 				if (err) {
 					outputChannel.appendLine('Installing ' + getImportPath(tool, goVersion) + ' FAILED');

From 09109888643c537c92f8caa185e09a089de305bf Mon Sep 17 00:00:00 2001
From: Rebecca Stambler <rstambler@golang.org>
Date: Mon, 23 Dec 2019 15:30:48 -0500
Subject: [PATCH 2/2] only write file when modules are on

---
 src/goInstallTools.ts | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/goInstallTools.ts b/src/goInstallTools.ts
index 01345ea75..216ea1047 100644
--- a/src/goInstallTools.ts
+++ b/src/goInstallTools.ts
@@ -138,16 +138,16 @@ export function installTools(missing: Tool[], goVersion: GoVersion): Promise<voi
 		// Disable modules for tools which are installed with the "..." wildcard.
 		// TODO: ... will be supported in Go 1.13, so enable these tools to use modules then.
 		const modulesOffForTool = modulesOff || disableModulesForWildcard(tool, goVersion);
+		let tmpGoModFile: string;
 		if (modulesOffForTool) {
 			envForTools['GO111MODULE'] = 'off';
 		} else {
 			envForTools['GO111MODULE'] = 'on';
+			// Write a temporary go.mod file to avoid version conflicts.
+			tmpGoModFile = path.join(toolsTmpDir, 'go.mod');
+			fs.writeFileSync(tmpGoModFile, 'module tools');
 		}
 
-		// Write a temporary go.mod file. This shouldn't affect anything if we've explicitly disabled modules.
-		const tmpGoModFile = path.join(toolsTmpDir, 'go.mod');
-		fs.writeFileSync(tmpGoModFile, 'module tools');
-
 		return res.then(sofar => new Promise<string[]>((resolve, reject) => {
 			const opts = {
 				env: envForTools,
@@ -155,7 +155,7 @@ export function installTools(missing: Tool[], goVersion: GoVersion): Promise<voi
 			};
 			const callback = (err: Error, stdout: string, stderr: string) => {
 				// Make sure to delete the temporary go.mod file, if it exists.
-				if (fs.existsSync(tmpGoModFile)) {
+				if (tmpGoModFile && fs.existsSync(tmpGoModFile)) {
 					fs.unlinkSync(tmpGoModFile);
 				}
 				if (err) {