fix(vm): show func for safe calls in disassembly

compiler/compiler.go

@@ -1103,7 +1103,9 @@ func (c *compiler) BuiltinNode(node *ast.BuiltinNode) {
 		if f.Fast != nil {
 			c.emit(OpCallBuiltin1, id)
 		} else if f.Safe != nil {
-			c.emit(OpPush, c.addConstant(f.Safe))
+			id := c.addConstant(f.Safe)
+			c.emit(OpPush, id)
+			c.debugInfo[fmt.Sprintf("const_%d", id)] = node.Name
 			c.emit(OpCallSafe, len(node.Arguments))
 		} else if f.Func != nil {
 			c.emitFunction(f, len(node.Arguments))

test/issues/567/issue_test.go

@@ -0,0 +1,25 @@
+package expr_test
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/expr-lang/expr"
+	"github.com/expr-lang/expr/internal/testify/require"
+)
+
+func TestIssue567(t *testing.T) {
+	program, err := expr.Compile("concat(1..2, 3..4)")
+	require.NoError(t, err)
+
+	var buf bytes.Buffer
+	program.DisassembleWriter(&buf)
+	output := buf.String()
+
+	// Check if "concat" is mentioned in the output
+	require.True(t, strings.Contains(output, "concat"), "expected 'concat' in disassembly output")
+
+	// It should appear as a pushed constant
+	require.True(t, strings.Contains(output, "OpPush\t<4>\tconcat"), "expected 'OpPush <4> concat' in disassembly output")
+}

vm/program.go

@@ -112,6 +112,9 @@ func (program *Program) DisassembleWriter(w io.Writer) {
 			} else {
 				c = "out of range"
 			}
+			if name, ok := program.debugInfo[fmt.Sprintf("const_%d", arg)]; ok {
+				c = name
+			}
 			if r, ok := c.(*regexp.Regexp); ok {
 				c = r.String()
 			}