4 files changed, 39 insertions, 21 deletions
diff --git a/src/cmd/go/alldocs.go b/src/cmd/go/alldocs.go
index 52aa6c7fb4..4be78b33bb 100644
--- a/src/cmd/go/alldocs.go
+++ b/src/cmd/go/alldocs.go
@@ -2878,11 +2878,11 @@
 // GOPATH mode import path checking (see 'go help importpath').
 //
 // In GOPATH mode, the default GODEBUG values built into a binary
-// will be those used in Go 1.20, setting the same GODEBUG values
-// as when a module specifies "godebug default=go1.20". To use
-// different GODEBUG settings, the GODEBUG environment variable must
-// be set to override those values. This also means that the standard
-// library tests will not run properly with GO111MODULE=off.
+// will be the same GODEBUG values as when a module specifies
+// "godebug default=go1.20". To use different GODEBUG settings, the
+// GODEBUG environment variable must be set to override those values.
+// This also means that the standard library tests will not run
+// properly with GO111MODULE=off.
 //
 // See https://go.dev/s/go15vendor for details.
 //
diff --git a/src/cmd/go/internal/help/helpdoc.go b/src/cmd/go/internal/help/helpdoc.go
index 5f77b88536..4b1444ee3b 100644
--- a/src/cmd/go/internal/help/helpdoc.go
+++ b/src/cmd/go/internal/help/helpdoc.go
@@ -525,11 +525,11 @@ Code in GOPATH mode vendor directories is not subject to
 GOPATH mode import path checking (see 'go help importpath').
 
 In GOPATH mode, the default GODEBUG values built into a binary
-will be those used in Go 1.20, setting the same GODEBUG values
-as when a module specifies "godebug default=go1.20". To use
-different GODEBUG settings, the GODEBUG environment variable must
-be set to override those values. This also means that the standard
-library tests will not run properly with GO111MODULE=off.
+will be the same GODEBUG values as when a module specifies
+"godebug default=go1.20". To use different GODEBUG settings, the
+GODEBUG environment variable must be set to override those values.
+This also means that the standard library tests will not run
+properly with GO111MODULE=off.
 
 See https://go.dev/s/go15vendor for details.
 
diff --git a/src/cmd/go/internal/load/godebug.go b/src/cmd/go/internal/load/godebug.go
index 7bb873fa7d..a6bcdad627 100644
--- a/src/cmd/go/internal/load/godebug.go
+++ b/src/cmd/go/internal/load/godebug.go
@@ -42,6 +42,24 @@ func ParseGoDebug(text string) (key, value string, err error) {
 	return k, v, nil
 }
 
+func defaultGODEBUGGoVersion(loaderstate *modload.State, p *Package) string {
+	if !loaderstate.Enabled() {
+		// GOPATH mode. Use Go 1.20.
+		return "1.20"
+	}
+	if loaderstate.RootMode == modload.NoRoot && p.Module != nil {
+		// This is go install pkg@version or go run pkg@version.
+		// Use the Go version from the package.
+		// If there isn't one, then assume Go 1.20, the last
+		// version before GODEBUGs were introduced (#56986).
+		if goVersion := p.Module.GoVersion; goVersion != "" {
+			return goVersion
+		}
+		return "1.20"
+	}
+	return loaderstate.MainModules.GoVersion(loaderstate)
+}
+
 // defaultGODEBUG returns the default GODEBUG setting for the main package p.
 // When building a test binary, directives, testDirectives, and xtestDirectives
 // list additional directives from the package under test.
@@ -49,17 +67,8 @@ func defaultGODEBUG(loaderstate *modload.State, p *Package, directives, testDire
 	if p.Name != "main" {
 		return ""
 	}
-	goVersion := loaderstate.MainModules.GoVersion(loaderstate)
-	if loaderstate.RootMode == modload.NoRoot && p.Module != nil {
-		// This is go install pkg@version or go run pkg@version.
-		// Use the Go version from the package.
-		// If there isn't one, then assume Go 1.20,
-		// the last version before GODEBUGs were introduced.
-		goVersion = p.Module.GoVersion
-		if goVersion == "" {
-			goVersion = "1.20"
-		}
-	}
+
+	goVersion := defaultGODEBUGGoVersion(loaderstate, p)
 
 	var m map[string]string
 
diff --git a/src/cmd/go/testdata/script/godebug_default_gopath.txt b/src/cmd/go/testdata/script/godebug_default_gopath.txt
new file mode 100644
index 0000000000..2bdf8369ae
--- /dev/null
+++ b/src/cmd/go/testdata/script/godebug_default_gopath.txt
@@ -0,0 +1,9 @@
+env GO111MODULE=off
+
+go list -f '{{.DefaultGODEBUG}}'
+! stdout netedns0
+
+-- foo.go --
+package main
+
+func main() {}
+\ No newline at end of file