unsignedlint

unsignedlint

Go linter which finds potentially unsafe unsigned integer subtractions in Go code.

The linter checks for binary expressions of the form x - y where y is an unsigned integer type (uint, uint8, uint16, uint32, uint64, uintptr). Such operations can lead to unexpected integer wraps (underflow) if y > x at runtime.

Note: This initial version flags all such subtractions. It does not currently check for safety guards (like if x >= y { ... x - y ... }). Adding such checks requires more complex static analysis.

Installation

go install github.com/fingon/unsignedlint@latest

Usage

Run the linter on your package:

go vet -vettool=$(which unsignedlint) ./...

Or directly:

unsignedlint ./...

Example

Code like this will be flagged:

package main

func main() {
	var a uint = 5
	var b uint = 10
	c := a - b // Potential underflow: unsignedlint will report this line
	println(c)
}

Known issues

Running it stand-alone may sometimes not work (Go bug? Who knows):

> unsignedlint ./...
unsignedlint: internal error: package "iter" without types was imported from "..."

In this case, go vet seems to work, for some reason.