io: preserve numeric string arguments when writing

io.go

@@ -92,11 +92,7 @@ func close(l *State) int {
 func write(l *State, f *os.File, argIndex int) int {
 	var err error
 	for argCount := l.Top(); argIndex < argCount && err == nil; argIndex++ {
-		if n, ok := l.ToNumber(argIndex); ok {
-			_, err = f.WriteString(numberToString(n))
-		} else {
-			_, err = f.WriteString(CheckString(l, argIndex))
-		}
+		_, err = f.WriteString(CheckString(l, argIndex))
 	}
 	if err == nil {
 		return 1

io_test.go

@@ -0,0 +1,37 @@
+package lua
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestWritePreservesNumericStrings(t *testing.T) {
+	for _, writer := range []string{"io.write", "f:write"} {
+		t.Run(writer, func(t *testing.T) {
+			filename := filepath.Join(t.TempDir(), "output")
+			l := NewState()
+			OpenLibraries(l)
+			l.PushString(filename)
+			l.SetGlobal("filename")
+			if err := DoString(l, fmt.Sprintf(`
+				local f = assert(io.open(filename, "wb"))
+				io.output(f)
+				assert(%s("123 ", "456 ", "Hello, ", "world!\n") == f)
+				assert(%s("001.20 ", " 0x10 ", "1e+02 ", 2.5, "\n") == f)
+				assert(f:close())
+			`, writer, writer)); err != nil {
+				t.Fatal(err)
+			}
+			output, err := os.ReadFile(filename)
+			if err != nil {
+				t.Fatal(err)
+			}
+			const expected = "123 456 Hello, world!\n001.20  0x10 1e+02 2.5\n"
+			if string(output) != expected {
+				t.Errorf("got %q, want %q", output, expected)
+			}
+		})
+	}
+}