"Ineffectual assignment" false positive when var used in deferred function call

[danutavadanei]

ineffassign version: last version available
go version: go version go1.18.3

Running the linter when interacting with a var after passing it to a deferred function call marks it as ineffectual assignment

package main

import "errors"

func shutdown(err error) {
    if err != nil {
        panic(err)
    }
}

func TestLint() {
    var err error
    defer shutdown(err)

    if true {
        err = errors.New("new error message") // test.go:16:9: ineffectual assignment to err
    }
}

Expectation: should not reported.

Output

ineffassign ./...
go-lint-issue/cmd/test.go:16:9: ineffectual assignment to err

[gordonklaus]

Arguments to a deferred function call are evaluated at the `defer` statement. Your assignment to `err` doesn't have the effect that you think it does.

…

On Fri, Jun 17, 2022, 11:52 Danut Avadanei ***@***.***> wrote: ineffassign version: last version available go version: go version go1.18.3 Running the linter when interacting with a var after passing it to a deferred function call marks it as ineffectual assignment package main import "errors" func shutdown(err error) { if err != nil { panic(err) } } func TestLint() { var err error defer shutdown(err) if true { err = errors.New("new error message") // test.go:16:9: ineffectual assignment to err } } Expectation: should not reported. Output ineffassign ./... go-lint-issue/cmd/test.go:16:9: ineffectual assignment to err — Reply to this email directly, view it on GitHub <#71>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAMP7UATJ36VZX4ZDT54NSDVPRDE3ANCNFSM5ZBXP5SQ> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[danutavadanei]

Got it, thanks! Fixed my code with defer func() { shutdown(err) }()