From d0a0606841937cd6dd1db7a95ebd9d6e7ad02d96 Mon Sep 17 00:00:00 2001
From: "Bryan C. Mills" <bcmills@google.com>
Date: Tue, 1 Feb 2022 16:59:41 -0500
Subject: [PATCH] cmd/go: fail 'go work' subcommands with a more helpful error
 if no go.work file exists

Otherwise, the failure mode for these subcommands refers to an empty file path:
	go: open : no such file or directory

Fixes #50964

Change-Id: I8776431a294d2b2246d7d147b6059054f31bc255
Reviewed-on: https://go-review.googlesource.com/c/go/+/382246
Trust: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
---
 src/cmd/go/internal/workcmd/edit.go        | 26 +++++++++++++---------
 src/cmd/go/internal/workcmd/sync.go        |  6 +++--
 src/cmd/go/internal/workcmd/use.go         |  3 +++
 src/cmd/go/testdata/script/work_nowork.txt | 20 +++++++++++++++++
 4 files changed, 42 insertions(+), 13 deletions(-)
 create mode 100644 src/cmd/go/testdata/script/work_nowork.txt

diff --git a/src/cmd/go/internal/workcmd/edit.go b/src/cmd/go/internal/workcmd/edit.go
index 879ddc3b1d..e7b1b13271 100644
--- a/src/cmd/go/internal/workcmd/edit.go
+++ b/src/cmd/go/internal/workcmd/edit.go
@@ -115,17 +115,6 @@ func init() {
 }
 
 func runEditwork(ctx context.Context, cmd *base.Command, args []string) {
-	anyFlags :=
-		*editGo != "" ||
-			*editJSON ||
-			*editPrint ||
-			*editFmt ||
-			len(workedits) > 0
-
-	if !anyFlags {
-		base.Fatalf("go: no flags specified (see 'go help work edit').")
-	}
-
 	if *editJSON && *editPrint {
 		base.Fatalf("go: cannot use both -json and -print")
 	}
@@ -147,6 +136,21 @@ func runEditwork(ctx context.Context, cmd *base.Command, args []string) {
 		}
 	}
 
+	if gowork == "" {
+		base.Fatalf("go: no go.work file found\n\t(run 'go work init' first or specify path using -workfile flag)")
+	}
+
+	anyFlags :=
+		*editGo != "" ||
+			*editJSON ||
+			*editPrint ||
+			*editFmt ||
+			len(workedits) > 0
+
+	if !anyFlags {
+		base.Fatalf("go: no flags specified (see 'go help work edit').")
+	}
+
 	workFile, err := modload.ReadWorkFile(gowork)
 	if err != nil {
 		base.Fatalf("go: errors parsing %s:\n%s", base.ShortPath(gowork), err)
diff --git a/src/cmd/go/internal/workcmd/sync.go b/src/cmd/go/internal/workcmd/sync.go
index 1cca817517..948fc5d370 100644
--- a/src/cmd/go/internal/workcmd/sync.go
+++ b/src/cmd/go/internal/workcmd/sync.go
@@ -43,9 +43,11 @@ func init() {
 }
 
 func runSync(ctx context.Context, cmd *base.Command, args []string) {
-	modload.InitWorkfile()
-
 	modload.ForceUseModules = true
+	modload.InitWorkfile()
+	if modload.WorkFilePath() == "" {
+		base.Fatalf("go: no go.work file found\n\t(run 'go work init' first or specify path using -workfile flag)")
+	}
 
 	workGraph := modload.LoadModGraph(ctx, "")
 	_ = workGraph
diff --git a/src/cmd/go/internal/workcmd/use.go b/src/cmd/go/internal/workcmd/use.go
index a5ba6c7133..d3bc1b7d55 100644
--- a/src/cmd/go/internal/workcmd/use.go
+++ b/src/cmd/go/internal/workcmd/use.go
@@ -49,6 +49,9 @@ func runUse(ctx context.Context, cmd *base.Command, args []string) {
 	modload.InitWorkfile()
 	gowork = modload.WorkFilePath()
 
+	if gowork == "" {
+		base.Fatalf("go: no go.work file found\n\t(run 'go work init' first or specify path using -workfile flag)")
+	}
 	workFile, err := modload.ReadWorkFile(gowork)
 	if err != nil {
 		base.Fatalf("go: %v", err)
diff --git a/src/cmd/go/testdata/script/work_nowork.txt b/src/cmd/go/testdata/script/work_nowork.txt
new file mode 100644
index 0000000000..b0320cbccb
--- /dev/null
+++ b/src/cmd/go/testdata/script/work_nowork.txt
@@ -0,0 +1,20 @@
+! go work use
+stderr '^go: no go\.work file found\n\t\(run ''go work init'' first or specify path using -workfile flag\)$'
+
+! go work use .
+stderr '^go: no go\.work file found\n\t\(run ''go work init'' first or specify path using -workfile flag\)$'
+
+! go work edit
+stderr '^go: no go\.work file found\n\t\(run ''go work init'' first or specify path using -workfile flag\)$'
+
+! go work edit -go=1.18
+stderr '^go: no go\.work file found\n\t\(run ''go work init'' first or specify path using -workfile flag\)$'
+
+! go work sync
+stderr '^go: no go\.work file found\n\t\(run ''go work init'' first or specify path using -workfile flag\)$'
+
+-- go.mod --
+module example
+go 1.18
+-- README.txt --
+There is no go.work file here.