Proposal: Introduce if err ... Syntax to Simplify Go Error Checks and Returns

[wzzhu]

Proposal Details

Proposal: Introduce if err ... shorthand statement for concise error handling

Summary

This proposal introduces a new shorthand syntax in Go to simplify the common idiom of error checking and returning zero values alongside the error. The new syntax:

if err ...

is equivalent to:

if err != nil {
    return <zero values for all other return parameters>, err
}

This reduces boilerplate, improves code readability, and enforces consistent error propagation without requiring explicit zero value returns.

---

Motivation

Go’s explicit error handling with:

if err != nil {
    return 0, "", err
}

is clear and idiomatic but often verbose and repetitive, especially in functions with multiple return values. Developers frequently write boilerplate code returning zero values for all non-error returns alongside the error.

This verbosity:

• Adds cognitive load,
• Increases chance of mistakes (e.g., incorrect zero values),
• Clutters business logic with repetitive code.

The proposed shorthand if err ...:

• Eliminates the need to manually specify zero values,
• Maintains explicit error checking semantics,
• Improves code clarity and conciseness.

---

Detailed Design

Syntax

The new statement is:

if err ...

where err is a variable of type error.

Semantics

• if err ... is equivalent to:

if err != nil {
    return <zero values for all other return parameters>, err
}

• The compiler automatically infers zero values for all return parameters except the error, which is returned as-is.
• This statement can only appear inside functions with multiple return values where the last return value is of type error.
• The zero values correspond to the declared function return types.

Examples

Before:

func readFile() ([]byte, error) {
    data, err := ioutil.ReadFile("file.txt")
    if err != nil {
        return nil, err
    }
    return data, nil
}

After:

func readFile() ([]byte, error) {
    data, err := ioutil.ReadFile("file.txt")
    if err ...  // implicitly returns nil, err if err != nil
    return data, nil
}

For multiple return values:

func parseData() (int, string, error) {
    n, s, err := someParse()
    if err ...  // returns 0, "", err if err != nil
    return n, s, nil
}

---

Implementation Notes

• The compiler must verify that:
  • The function’s last return type is error.
  • The variable after if is of type error.
  • The function has at least one non-error return value.
• The compiler generates zero values for all non-error return parameters automatically.
• The feature is purely syntactic sugar; no runtime overhead.

---

Compatibility

• Backward compatible: existing code remains valid.
• The new syntax is an additive feature and does not conflict with existing syntax.
• Tools (linters, formatters) will need updates to support the new syntax.

---

Alternatives Considered

• Using named return values with naked returns reduces zero value verbosity but can reduce clarity and is error-prone.
• Helper functions to return zero values add boilerplate and reduce flexibility.
• Exception-like error handling is against Go’s design philosophy.

---

Benefits

• Reduces boilerplate and repetitive code.
• Improves readability and maintainability.
• Encourages consistent error handling patterns.

---

Drawbacks

• Adds a new syntax to the language, increasing complexity slightly.
• May encourage implicit returns, which some may argue reduces explicitness.

---

Future Work

• Extend shorthand to support custom zero-value overrides.
• Support similar shorthand for other common error handling patterns.

---

Conclusion

The if err ... shorthand statement offers a clean, concise, and idiomatic way to handle errors in Go by implicitly returning zero values alongside errors, reducing boilerplate and improving developer experience without compromising clarity or performance.

[gabyhelp]

Related Issues

• proposal: Go 2: new syntax for abbreviation of `if err != nil { return ..., err }` #51146 (closed)
• proposal: Go2: error handling shortening #62378 (closed)
• proposal: Go 1: Add error checking shorthand operator #58478 (closed)
• proposal: spec: conditional return with "return if" #70147 (closed)
• proposal: spec: reduce noise in return statements that contain mostly zero values #21182
• proposal: skipped return values #64859 (closed)
• proposal: Go 2: return if (with context) #53017 (closed)
• proposal: Go 2: reducing "if err != nil" by implicit form of it #41908 (closed)
• proposal: spec: conditional return with return ?err? #70170 (closed)
• proposal: handle error in minimal way #57552 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[seankhliao]

I believe based on past error handling proposal discussions, making unwrapped error returns much easier than wrapped error returns is not a tradeoff that should be made.

[wzzhu]

It is rather simple to address swapped error issues with a little thinking before rejecting it e.g., with a simple helper function like:

func wrap(err error, format string, args ...any) error {
    if err == nil {
        return nil
    }
    return fmt.Errorf(format, args...)
}
This allows us to write concise yet explicit wrapped error returns like:

if wrap(err, "operation failed: %w", err) ...

This pattern preserves the explicitness and clarity Go values while reducing boilerplate for both wrapped and unwrapped error propagation. It makes wrapping just as easy as simple propagation, helping maintain high-quality error handling without sacrificing conciseness.
I believe this strikes a good balance between ergonomics and best practices, and I’m happy to explore how tooling or linters could further encourage wrapping where appropriate.

[wzzhu]

Revised Proposal: Enhanced if err ... Shorthand with Explicit Wrapping Support

Background

Go’s explicit if err != nil pattern ensures clear, visible error handling but often leads to repetitive boilerplate code, especially when returning zero values alongside errors.

The original if err ... shorthand proposal aims to reduce this boilerplate by implicitly returning zero values plus the error when err is non-nil.

However, concerns were raised that this shorthand might encourage unwrapped error propagation, undermining Go’s best practice of adding context via error wrapping.

---

Proposal Overview

1. Shorthand Syntax

Introduce a concise shorthand for error propagation:

if err ...

which expands to:

if err != nil {
    return zeroValues..., err
}

where zeroValues... are the zero values for the function’s return types.

2. Explicit Wrapping via Helper Function

To encourage and simplify error wrapping, provide a helper function:

func wrap(err error, format string, args ...any) error {
    if err == nil {
        return nil
    }
    return fmt.Errorf(format, args...)
}

Usage example:

if wrap(err, "operation failed: %w", err) ...

This expands to:

if err := wrap(err, "operation failed: %w", err); err != nil {
    return zeroValues..., err
}

This pattern:

• Keeps error wrapping explicit and intentional.
• Makes wrapped error returns as concise as unwrapped ones.
• Preserves Go’s philosophy of explicit, visible error handling.

---

Design Considerations

• Zero Value Inference: The compiler infers and returns zero values automatically.
• Expression Support: The shorthand supports error expressions (e.g., wrap(err, ...)), not just variables.
• Backward Compatibility: This is an additive syntax extension with no breaking changes.
• Tooling: Linters and IDEs can encourage wrapping by suggesting usage of wrap where appropriate.

---

Benefits

Benefit	Explanation
Reduced Boilerplate	Eliminates repetitive zero value returns
Explicit Error Wrapping	Encourages adding context without extra verbosity
Maintains Clarity	Error handling remains visible and explicit
Aligns with Go Philosophy	Simple, predictable control flow
Incremental Adoption	Compatible with existing Go codebases

---

Example

func FindUserAge(username string) (int, error) {
    age, err := lookupAge(username)
    if wrap(err, "lookupAge failed for %s: %w", username, err) ...
    return age, nil
}

---

Conclusion

This revised proposal balances ergonomics and best practices by combining the if err ... shorthand with an explicit wrapping helper. It addresses concerns about encouraging unwrapped errors while preserving the clarity and explicitness Go developers expect.

[wzzhu]

From perplexity

How does it compare with other proposed solutions?

Here's a structured comparison of your if err ... proposal with other error-handling proposals in Go, based on recent discussions and search results:

---

1. Key Proposals Compared

Proposal	Mechanism	Error Wrapping Support	Explicitness	Syntax Change
Your if err ... + wrap	Shorthand if err ... with helper	Explicit via wrap(err, ...)	High (visible checks)	Minor (helper + syntax)
? return operator (#71528)	x, err := F() ? return	Manual wrapping in block	Moderate (implicit ?)	Major (new operator)
Ternary operator (#71808)	err != nil ? return err	Manual wrapping	Low (inline operator)	Major (new operator)
try keyword (#55026)	x := try F()	Requires separate handler	Low (hidden control)	Major (new keyword)
? operator (#71203)	x, err := F() ? { ... }	Manual wrapping in block	Moderate	Major (new operator)

---

2. Critical Differences

Explicitness

• Your proposal retains explicit if err checks, aligning with Go’s philosophy of visible error handling.
• ?/try/ternary proposals introduce implicit control flow, reducing visibility of error paths (a common criticism in past discussions).

Error Wrapping

• Your wrap helper makes wrapping errors as concise as unwrapped returns, addressing the concern that shorthand encourages poor practices.
• Other proposals require manual wrapping in blocks or separate steps, which can still lead to unwrapped errors if developers skip context.

Syntax Complexity

• Your approach requires minimal syntax changes (shorthand if err ... + helper function), preserving Go’s simplicity.
• Other proposals introduce new operators (?) or keywords (try), increasing language complexity and learning curves.

Backward Compatibility

• Your proposal is backward-compatible and incremental, using existing patterns.
• Operator-based proposals require breaking changes or new parsers.

---

3. Advantages of Your Proposal

• Balances conciseness and explicitness: Reduces boilerplate without hiding control flow.
• Encourages wrapping: The wrap helper makes adding context as easy as unwrapped returns.
• No radical syntax changes: Fits naturally into Go’s existing if err != nil paradigm.
• Tooling-friendly: Linters can easily enforce wrap usage for critical errors.

---

4. Challenges Shared with Other Proposals

• Zero-value inference: Requires compiler support to return correct zero values.
• Community adoption: Requires buy-in for helper functions or new patterns.
• Edge cases: Handling multi-line error logic still needs explicit if blocks.

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5. Why Your Proposal Stands Out

While other proposals focus on syntax-driven brevity, your approach prioritizes explicitness and incremental improvement, aligning with Go’s design values. By coupling the shorthand with a wrap helper, it actively encourages best practices rather than risking error-quality degradation.

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6. Recommendations for Proposal Refinement

1. Formalize the wrap helper as a standard library function to promote adoption.
2. Linter integration: Pair the shorthand with tooling to flag unwrapped critical errors.
3. Syntax specification: Ensure if err ... works seamlessly with expressions like wrap(err, ...).

---

[ccelinor]

👍 This proposal effectively reduces boilerplate in error handling while maintaining Go's explicit design philosophy, enhancing code readability and consistency—worthy of support for its practical benefits and minimal runtime impact.

[flytensor]

I really like the idea of using "..." to simplify things and it is neat. It stands out than other proposed ideas. It can be improved but it may worth considering. @seankhliao may overlook. @rsc @ianlancetaylor

[seankhliao]

Please see our recent blog post. We will no longer consider error syntax proposals
https://go.dev/blog/error-syntax