4 files changed, 41 insertions, 11 deletions

diff --git a/misc/reboot/reboot_test.go b/misc/reboot/reboot_test.go
index c4a9f3ef9f..94d61e000e 100644
--- a/misc/reboot/reboot_test.go
+++ b/misc/reboot/reboot_test.go
@@ -7,10 +7,13 @@
 package reboot_test
 
 import (
+	"fmt"
+	"io"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strings"
 	"testing"
 	"time"
 )
@@ -67,12 +70,27 @@ func TestRepeatBootstrap(t *testing.T) {
 		makeScript = "make.bash"
 	}
 
+	var stdout strings.Builder
 	cmd := exec.Command(filepath.Join(goroot, "src", makeScript))
 	cmd.Dir = gorootSrc
-	cmd.Env = append(cmd.Environ(), "GOROOT=", "GOROOT_BOOTSTRAP="+realGoroot)
+	cmd.Env = append(cmd.Environ(), "GOROOT=", "GOROOT_FINAL=", "GOROOT_BOOTSTRAP="+realGoroot)
 	cmd.Stderr = os.Stderr
-	cmd.Stdout = os.Stdout
+	cmd.Stdout = io.MultiWriter(os.Stdout, &stdout)
 	if err := cmd.Run(); err != nil {
 		t.Fatal(err)
 	}
+
+	// Test that go.dev/issue/42563 hasn't regressed.
+	t.Run("PATH reminder", func(t *testing.T) {
+		var want string
+		switch gorootBin := filepath.Join(goroot, "bin"); runtime.GOOS {
+		default:
+			want = fmt.Sprintf("*** You need to add %s to your PATH.", gorootBin)
+		case "plan9":
+			want = fmt.Sprintf("*** You need to bind %s before /bin.", gorootBin)
+		}
+		if got := stdout.String(); !strings.Contains(got, want) {
+			t.Errorf("reminder %q is missing from %s stdout:\n%s", want, makeScript, got)
+		}
+	})
 }
diff --git a/src/all.bash b/src/all.bash
index 5d994d3d0d..5f8e8fec63 100755
--- a/src/all.bash
+++ b/src/all.bash
@@ -8,8 +8,6 @@ if [ ! -f make.bash ]; then
 	echo 'all.bash must be run from $GOROOT/src' 1>&2
 	exit 1
 fi
-OLDPATH="$PATH"
 . ./make.bash "$@" --no-banner
 bash run.bash --no-rebuild
-PATH="$OLDPATH"
 $GOTOOLDIR/dist banner  # print build info
diff --git a/src/all.bat b/src/all.bat
index dfc83c8b26..d5abec141f 100644
--- a/src/all.bat
+++ b/src/all.bat
@@ -12,15 +12,10 @@ echo all.bat must be run from go\src
 goto end

 :ok

 

-set OLDPATH=%PATH%

 call .\make.bat --no-banner --no-local

 if %GOBUILDFAIL%==1 goto end

 call .\run.bat --no-rebuild --no-local

 if %GOBUILDFAIL%==1 goto end

-:: we must restore %PATH% before running "dist banner" so that the latter

-:: can get the original %PATH% and give suggestion to add %GOROOT%/bin

-:: to %PATH% if necessary.

-set PATH=%OLDPATH%

 "%GOTOOLDIR%/dist" banner

 

 :end

diff --git a/src/cmd/dist/build.go b/src/cmd/dist/build.go
index 6dbc9951a9..e460b2d1cc 100644
--- a/src/cmd/dist/build.go
+++ b/src/cmd/dist/build.go
@@ -1252,7 +1252,7 @@ func cmdenv() {
 	windows := flag.Bool("w", gohostos == "windows", "emit windows syntax")
 	xflagparse(0)
 
-	format := "%s=\"%s\"\n"
+	format := "%s=\"%s\";\n" // Include ; to separate variables when 'dist env' output is used with eval.
 	switch {
 	case *plan9:
 		format = "%s='%s'\n"
@@ -1299,6 +1299,17 @@ func cmdenv() {
 			sep = ";"
 		}
 		xprintf(format, "PATH", fmt.Sprintf("%s%s%s", gorootBin, sep, os.Getenv("PATH")))
+
+		// Also include $DIST_UNMODIFIED_PATH with the original $PATH
+		// for the internal needs of "dist banner", along with export
+		// so that it reaches the dist process. See its comment below.
+		var exportFormat string
+		if !*windows && !*plan9 {
+			exportFormat = "export " + format
+		} else {
+			exportFormat = format
+		}
+		xprintf(exportFormat, "DIST_UNMODIFIED_PATH", os.Getenv("PATH"))
 	}
 }
 
@@ -1897,7 +1908,15 @@ func banner() {
 		if gohostos == "windows" {
 			pathsep = ";"
 		}
-		if !strings.Contains(pathsep+os.Getenv("PATH")+pathsep, pathsep+gorootBin+pathsep) {
+		path := os.Getenv("PATH")
+		if p, ok := os.LookupEnv("DIST_UNMODIFIED_PATH"); ok {
+			// Scripts that modify $PATH and then run dist should also provide
+			// dist with an unmodified copy of $PATH via $DIST_UNMODIFIED_PATH.
+			// Use it here when determining if the user still needs to update
+			// their $PATH. See go.dev/issue/42563.
+			path = p
+		}
+		if !strings.Contains(pathsep+path+pathsep, pathsep+gorootBin+pathsep) {
 			xprintf("*** You need to add %s to your PATH.\n", gorootBin)
 		}
 	}