[BUG] Linter ignores span.End if called inside deferred function

[bmon]

Describe the bug
I have some code that calls span.End() inside a deferred function because I also want to trap and record panics via recover().

Unfortunately this linter does not recognise that span.End() is called in the deferred function, and reports span.End is not called on all paths, possible memory leak

To Reproduce

package main

import (
	"context"

	"go.opentelemetry.io/otel"
)

func _() {
	_, span := otel.Tracer("foo").Start(context.Background(), "bar")
	defer func() {
		span.End()
	}()
}

$ spancheck ./...
/home/brendan/git/go-spancheck/testdata/base/defer.go:10:2: span.End is not called on all paths, possible memory leak
/home/brendan/git/go-spancheck/testdata/base/defer.go:14:1: return can be reached without calling span.End
exit status 3

Expected behavior
The linter recognises this as a safe span completion that cannot be skipped and won't leak spans.

[jjti]

Hey @bmon , thank you for pointing this point and giving a great+detailed example. I tried to address it here: #13

It'll now check FuncLiterals (1 level deep) for span calls like End() as in your example:

// This tests that we detect when the span is closed within a deferred func.
// https://github.com/jjti/go-spancheck/issues/12
func _() {
	_, span := otel.Tracer("foo").Start(context.Background(), "bar")
	defer func() {
		span.End()
	}()
}

// Despite above, we do not wander more than one level deep into the defer stack.
func _() {
	_, span := otel.Tracer("foo").Start(context.Background(), "bar") // want "span.End is not called on all paths, possible memory leak"
	defer func() {
		defer func() {
			span.End()
		}()
	}()
} // want "return can be reached without calling span.End"

I hope you'll try it out! It will be awhile before this fix is available in Golangci, tho