refactor(gasm): report the toolchain-recorded version

Assisted-by: GLM 5.3 Flash

cmd/gasm/main.go

@@ -18,6 +18,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"runtime/debug"
 	"slices"
 	"sort"
 	"strconv"
@@ -36,9 +37,16 @@ import (
 	"sourcedock.dev/petrbalvin/gasm-devkit/verify"
 )
 
-// version is the release version, stamped at build time via
-// -ldflags "-X main.version=…" (defaulting to the current release).
-var version = "0.33.0"
+// version reports the release the toolchain recorded for this build: the
+// tag on a tag, a pseudo-version below one, and (devel) outside version
+// control. Nothing is injected; the recorded value cannot go stale.
+func version() string {
+	bi, ok := debug.ReadBuildInfo()
+	if !ok || bi.Main.Version == "" {
+		return "(devel)"
+	}
+	return bi.Main.Version
+}
 
 func main() {
 	if len(os.Args) < 2 {
@@ -88,9 +96,9 @@ func main() {
 	}
 }
 
-// cmdVersion prints the release version.
+// cmdVersion prints the recorded version.
 func cmdVersion() int {
-	fmt.Printf("gasm %s\n", version)
+	fmt.Printf("gasm %s\n", version())
 	return 0
 }
 
@@ -119,7 +127,7 @@ func usage(w io.Writer) {
 		bold, cyan, yellow, gray, reset = colorBold, colorCyan, colorYellow, colorGray, colorReset
 	}
 
-	fmt.Fprintf(w, "%sgasm %s%s: developer tooling for Go's Plan 9 assembler (GAsm)%s\n\n", bold, version, reset, reset)
+	fmt.Fprintf(w, "%sgasm %s%s: developer tooling for Go's Plan 9 assembler (GAsm)%s\n\n", bold, version(), reset, reset)
 	fmt.Fprintf(w, "gasm bundles a lexer, parser, formatter, linter, standalone assembler and\n")
 	fmt.Fprintf(w, "language server for Plan 9 assembly into one self-contained binary.\n\n")
 
@@ -442,7 +450,7 @@ hover, document symbols, diagnostics and semantic-token highlighting.
 `)
 	fs.Parse(args)
 	srv := lsp.New(os.Stdin, os.Stdout)
-	srv.SetVersion(version)
+	srv.SetVersion(version())
 	if err := srv.Run(); err != nil {
 		fmt.Fprintln(os.Stderr, "gasm lsp:", err)
 		return 1

cmd/gasm/main_test.go

@@ -219,8 +219,9 @@ func TestCmdVersion(t *testing.T) {
 	if code != 0 {
 		t.Fatalf("code = %d", code)
 	}
-	if !strings.Contains(out, version) {
-		t.Errorf("version output %q does not mention %q", out, version)
+	got := version()
+	if !strings.Contains(out, got) {
+		t.Errorf("version output %q does not mention %q", out, got)
 	}
 }