Go: Make version parsing robust in the face of custom Go builds

jketema · jketema · commit ff9a7996546f · 2026-05-08T15:09:18.000+02:00
cf. https://github.com/golang/go/blob/afcf04cb6401b439ce9bdcd18448c512f5bfda77/src/go/version/version.go#L20
diff --git a/go/extractor/toolchain/toolchain.go b/go/extractor/toolchain/toolchain.go
@@ -130,7 +130,13 @@ func parseGoVersion(data string) string {
 	for sc.Scan() {
 		lastLine = sc.Text()
 	}
-	return strings.Fields(lastLine)[2]
+
+	var goVersion = strings.Fields(lastLine)[2]
+
+	// Drop custom build suffixes.
+	goVersion, _, _ = strings.Cut(goVersion, "-") 
+
+	return goVersion
 }
 
 // Returns a value indicating whether the system Go toolchain supports workspaces.
diff --git a/go/extractor/toolchain/toolchain_test.go b/go/extractor/toolchain/toolchain_test.go
@@ -9,6 +9,8 @@ import (
 func TestParseGoVersion(t *testing.T) {
 	tests := map[string]string{
 		"go version go1.18.9 linux/amd64": "go1.18.9",
+		"go version go1.26.3-X:nodwarf5 linux/amd64": "go1.26.3",
+		"go version go1.26.3rc1 linux/amd64": "go1.26.3rc1",
 		"warning: GOPATH set to GOROOT (/usr/local/go) has no effect\ngo version go1.18.9 linux/amd64": "go1.18.9",
 	}
 	for input, expected := range tests {

Original file line number	Diff line number	Diff line change
`@@ -130,7 +130,13 @@ func parseGoVersion(data string) string {`
`130`	`130`	`for sc.Scan() {`
`131`	`131`	`lastLine = sc.Text()`
`132`	`132`	`}`
`133`		`- return strings.Fields(lastLine)[2]`
	`133`	`+`
	`134`	`+ var goVersion = strings.Fields(lastLine)[2]`
	`135`	`+`
	`136`	`+ // Drop custom build suffixes.`
	`137`	`+ goVersion, _, _ = strings.Cut(goVersion, "-")`
	`138`	`+`
	`139`	`+ return goVersion`
`134`	`140`	`}`
`135`	`141`
`136`	`142`	`// Returns a value indicating whether the system Go toolchain supports workspaces.`
Original file line number	Diff line number	Diff line change
`@@ -9,6 +9,8 @@ import (`
`9`	`9`	`func TestParseGoVersion(t *testing.T) {`
`10`	`10`	`tests := map[string]string{`
`11`	`11`	`"go version go1.18.9 linux/amd64": "go1.18.9",`
	`12`	`+ "go version go1.26.3-X:nodwarf5 linux/amd64": "go1.26.3",`
	`13`	`+ "go version go1.26.3rc1 linux/amd64": "go1.26.3rc1",`
`12`	`14`	`"warning: GOPATH set to GOROOT (/usr/local/go) has no effect\ngo version go1.18.9 linux/amd64": "go1.18.9",`
`13`	`15`	`}`
`14`	`16`	`for input, expected := range tests {`