cmd/go/internal/modload: replace import error message from goroot to std

When importing a package that does not exist, it would show goroot error
message and path. We would like to replace goroot with std instead.

Fixes #56965.

Change-Id: I86f8a7fab6555b68f792a3a4686de20d51eced8b
Reviewed-on: https://go-review.googlesource.com/c/go/+/453895
Run-TryBot: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

Author: jchen038

src/cmd/go/internal/modload/import.go

@@ -57,7 +57,7 @@ type ImportMissingError struct {
 func (e *ImportMissingError) Error() string {
 	if e.Module.Path == "" {
 		if e.isStd {
-			msg := fmt.Sprintf("package %s is not in GOROOT (%s)", e.Path, filepath.Join(cfg.GOROOT, "src", e.Path))
+			msg := fmt.Sprintf("package %s is not in std (%s)", e.Path, filepath.Join(cfg.GOROOT, "src", e.Path))
 			if e.importerGoVersion != "" {
 				msg += fmt.Sprintf("\nnote: imported by a module that requires go %s", e.importerGoVersion)
 			}

src/cmd/go/testdata/script/cmd_import_error.txt

@@ -5,10 +5,10 @@ env GO111MODULE=on
 # a clear error in module mode.
 
 ! go list cmd/unknown
-stderr '^package cmd/unknown is not in GOROOT \('$GOROOT'[/\\]src[/\\]cmd[/\\]unknown\)$'
+stderr '^package cmd/unknown is not in std \('$GOROOT'[/\\]src[/\\]cmd[/\\]unknown\)$'
 
 go list -f '{{range .DepsErrors}}{{.Err}}{{end}}' x.go
-stdout '^package cmd/unknown is not in GOROOT \('$GOROOT'[/\\]src[/\\]cmd[/\\]unknown\)$'
+stdout '^package cmd/unknown is not in std \('$GOROOT'[/\\]src[/\\]cmd[/\\]unknown\)$'
 
 -- x.go --
 package x

src/cmd/go/testdata/script/mod_get_replaced.txt

@@ -80,7 +80,7 @@ stdout '^rsc.io/quote v1.4.0'
 cp go.mod.orig go.mod
 
 ! go list example
-stderr '^package example is not in GOROOT \(.*\)$'
+stderr '^package example is not in std \(.*\)$'
 ! go get example
 stderr '^go: malformed module path "example": missing dot in first path element$'
 

src/cmd/go/testdata/script/mod_goroot_errors.txt

@@ -11,24 +11,24 @@ env GO111MODULE=on
 ! go build -mod=readonly nonexist
 ! stderr 'import lookup disabled'
 ! stderr 'missing dot'
-stderr '^package nonexist is not in GOROOT \('$GOROOT'[/\\]src[/\\]nonexist\)$'
+stderr '^package nonexist is not in std \('$GOROOT'[/\\]src[/\\]nonexist\)$'
 
 ! go build nonexist
 ! stderr 'import lookup disabled'
 ! stderr 'missing dot'
-stderr '^package nonexist is not in GOROOT \('$GOROOT'[/\\]src[/\\]nonexist\)$'
+stderr '^package nonexist is not in std \('$GOROOT'[/\\]src[/\\]nonexist\)$'
 
 # Building a nonexistent std package indirectly should also fail usefully.
 
 ! go build -mod=readonly ./importnonexist
 ! stderr 'import lookup disabled'
 ! stderr 'missing dot'
-stderr '^importnonexist[/\\]x.go:2:8: package nonexist is not in GOROOT \('$GOROOT'[/\\]src[/\\]nonexist\)$'
+stderr '^importnonexist[/\\]x.go:2:8: package nonexist is not in std \('$GOROOT'[/\\]src[/\\]nonexist\)$'
 
 ! go build ./importnonexist
 ! stderr 'import lookup disabled'
 ! stderr 'missing dot'
-stderr '^importnonexist[/\\]x.go:2:8: package nonexist is not in GOROOT \('$GOROOT'[/\\]src[/\\]nonexist\)$'
+stderr '^importnonexist[/\\]x.go:2:8: package nonexist is not in std \('$GOROOT'[/\\]src[/\\]nonexist\)$'
 
 # Building an *actual* std package should fail if GOROOT is set to something bogus.
 
@@ -38,7 +38,7 @@ env GOROOT=$WORK/not-a-valid-goroot
 ! go build ./importjson
 ! stderr 'import lookup disabled'
 ! stderr 'missing dot'
-stderr 'importjson[/\\]x.go:2:8: package encoding/json is not in GOROOT \('$WORK'[/\\]not-a-valid-goroot[/\\]src[/\\]encoding[/\\]json\)$'
+stderr 'importjson[/\\]x.go:2:8: package encoding/json is not in std \('$WORK'[/\\]not-a-valid-goroot[/\\]src[/\\]encoding[/\\]json\)$'
 
 -- go.mod --
 module example.com

src/cmd/go/testdata/script/mod_issue35270.txt

@@ -10,7 +10,7 @@ stderr '^main.go:4:5: ambiguous import: found package image in multiple director
 
 cd ../c
 ! go build -mod=vendor
-stderr 'main.go:4:5: package p is not in GOROOT'
+stderr 'main.go:4:5: package p is not in std'
 
 -- a/go.mod --
 module image

src/cmd/go/testdata/script/mod_load_missing_std.txt

@@ -2,7 +2,7 @@
 # import is missing. See golang.org/issue/48966.
 
 ! go build .
-stderr '^main.go:3:8: package nonexistent is not in GOROOT \(.*\)$'
+stderr '^main.go:3:8: package nonexistent is not in std \(.*\)$'
 stderr '^note: imported by a module that requires go 1.99999$'
 
 -- go.mod --

src/cmd/go/testdata/script/mod_tidy_error.txt

@@ -4,12 +4,12 @@ env GO111MODULE=on
 # 'go mod tidy' and 'go mod vendor' should not hide loading errors.
 
 ! go mod tidy
-! stderr 'package nonexist is not in GOROOT'
+! stderr 'package nonexist is not in std'
 stderr '^issue27063 imports\n\tnonexist.example.com: cannot find module providing package nonexist.example.com'
 stderr '^issue27063 imports\n\tissue27063/other imports\n\tother.example.com/nonexist: cannot find module providing package other.example.com/nonexist'
 
 ! go mod vendor
-! stderr 'package nonexist is not in GOROOT'
+! stderr 'package nonexist is not in std'
 stderr '^issue27063 imports\n\tnonexist.example.com: no required module provides package nonexist.example.com; to add it:\n\tgo get nonexist.example.com$'
 stderr '^issue27063 imports\n\tissue27063/other imports\n\tother.example.com/nonexist: no required module provides package other.example.com/nonexist; to add it:\n\tgo get other.example.com/nonexist$'
 

src/cmd/go/testdata/script/mod_vendor.txt

@@ -55,7 +55,7 @@ stderr 'go: module diamondright: can''t resolve module using the vendor director
 go list -mod=mod -f {{.Dir}} w
 stdout 'src[\\/]w'
 ! go list -mod=vendor -f {{.Dir}} w
-stderr 'package w is not in GOROOT'
+stderr 'package w is not in std'
 
 go list -mod=mod -f {{.Dir}} diamondright
 stdout 'src[\\/]diamondright'

src/go/build/build_test.go

@@ -525,10 +525,10 @@ func TestImportDirNotExist(t *testing.T) {
 				errOk := (err != nil && strings.HasPrefix(err.Error(), "cannot find package"))
 				wantErr := `"cannot find package" error`
 				if test.srcDir == "" {
-					if err != nil && strings.Contains(err.Error(), "is not in GOROOT") {
+					if err != nil && strings.Contains(err.Error(), "is not in std") {
 						errOk = true
 					}
-					wantErr = `"cannot find package" or "is not in GOROOT" error`
+					wantErr = `"cannot find package" or "is not in std" error`
 				}
 				if !errOk {
 					t.Errorf("%s got error: %q, want %s", test.label, err, wantErr)