Warning Codes

This document lists the warning codes that the YaoXiang compiler may produce. Warnings do not prevent compilation but may indicate potential issues in the code.

Configuration

You can configure warning behavior through yaoxiang.toml:

[lint]
# dead-code warning level: off | warn | deny
dead-code = "warn"

• off: Disable the warning
• warn: Show the warning (default)
• deny: Treat the warning as an error

Warning List

W1001: Unused Exported Function

Reason: An exported function is never called by any code.

pub dead_function: () -> Void = { }  // W1001: Unused exported function

main = {
    // dead_function is never called
}

Suggestion:

• If the function doesn't need to be used externally, remove the pub modifier
• If the function needs to be kept but is temporarily unused, set dead-code = "off" in the configuration

---

W1002: Unused Exported Type

Reason: An exported type (type alias or custom type) is never used.

Example:

DeadType: Type = Int  // W1002: Unused exported type

main = {
    x = 42
}

Suggestion:

• If the type needs to be exported but is temporarily unused, ignore this warning

---

W1003: Unused Import

Reason: A module or symbol imported via use statement is never used.

use std.json  // W1003: Unused import

main = {
    // json module is never used
}

Suggestion:

• Remove unused imports to keep code clean
• If you need to keep the import (for side effects), consider using use std.json.* or add a comment explaining why

---

W1004: Unused Exported Variable

Reason: A variable exported with pub is never read.

Example:

pub dead_var = 42  // W1004: Unused exported variable

main = {
    // dead_var is never read
}

Suggestion:

• Remove the unnecessary pub modifier
• If the variable needs to be exported but is temporarily unused, ignore this warning

---

W1005: Unused Exported Method

Reason: A method exported on a type is never called.

Example:

Foo: Type = { value: Int }

pub Foo.dead_method: (self: Foo) -> Void = { }  // W1005: Unused exported method

main = {
    foo = Foo(1)
    // dead_method is never called
}

Suggestion:

• Remove the unnecessary pub modifier
• If the method needs to be kept but is temporarily unused, ignore this warning

---

Warning Levels Explained

Level	Effect
off	Completely disable this warning
warn	Show warning but continue compiling (default)
deny	Treat warning as error, block compilation

Use Cases

• During development: Use warn level to be aware of potential issues in the code
• Before release: Use deny level to ensure there is no unused code
• Legacy code: Use off level to temporarily ignore warnings

---

Difference from Error Codes

Warning codes use the W prefix (e.g., W1001), while error codes use the E prefix (e.g., E1001).

• Error: Blocks compilation and must be fixed
• Warning: Hints at potential issues and can be optionally fixed