Compatibility issues with sprig dig function between 1.16 and 1.17

[dmarquez-splunk]

Hello!

Very new to this repo so looking for some advice on what may be causing the issues I am about to describe.

I have a sample go program as follows:

package main

import (
	"fmt"

	"github.com/Masterminds/sprig/v3"
	"github.com/expr-lang/expr"
)

func main() {
	// Example map to test dig
	labels := map[string]any{
		"some": map[string]any{
			"label": map[string]any{
				"io/creator-email": "test@example.com",
			},
		},
	}

	// Build environment with dig
	env := map[string]any{
		"sprig":  sprig.GenericFuncMap(),
		"labels": labels,
	}

	// Compile expression
	program, err := expr.Compile("sprig.dig('some', 'label', 'io/creator-email', nil, labels)", expr.Env(env))
	if err != nil {
		fmt.Println("Compile error:", err)
		return
	}

	// Run expression
	output, err := expr.Run(program, env)
	if err != nil {
		fmt.Println("Runtime error:", err)
		return
	}

	fmt.Println("Result:", output)
}

When using this program with expr-lang 1.16.9 I get:
Result: test@example.com

However, when upgrading to 1.17.X (while keeping sprig module the same) I get:

Runtime error: runtime error: index out of range [3] with length 1 (1:7)
 | sprig.dig('some', 'label', 'io/creator-email', nil, labels)
 | ......^

Any thought what may be causing this?

[thevilledev]

Hey!

I wrote a small test case to try and reproduce this:

func TestSprigDigCompatibility(t *testing.T) {
        // Simulating sprig.GenericFuncMap() - a map containing functions
        funcMap := map[string]any{
                "dig": func(ps ...any) (any, error) {
                        // Simplified dig implementation - just return the default value
                        if len(ps) < 2 {
                                return nil, nil
                        }
                        return ps[len(ps)-2], nil
                },
        }

        labels := map[string]any{
                "some": map[string]any{
                        "label": map[string]any{
                                "io/creator-email": "test@example.com",
                        },
                },
        }

        env := map[string]any{
                "sprig":  funcMap,
                "labels": labels,
        }

        program, err := expr.Compile("sprig.dig('some', 'label', 'io/creator-email', nil, labels)", expr.Env(env))
        require.NoError(t, err)

        output, err := expr.Run(program, env)
        require.NoError(t, err)
        require.Nil(t, output) // Our simplified dig returns the default (nil)

        // Print disassembly for debugging
        fmt.Println("Disassembly:")
        fmt.Println(program.Disassemble())
}

Runs fine on v1.16.9, but fails on all tagged releases after to the same error you're seeing:

runtime error: index out of range [3] with length 1 (1:7)

But the good thing is that it runs fine on master. I believe I fixed this in #868. It will be part of the next release, presumably v1.17.7.

[antonmedv]

Yes! I will release v1.17.7 very soon 🙌