makezero doesn't recognize non-empty slices in function calls or return statements

[ashanbrown]

A bad append could happen in another function. This is probably why it's best to just never initialize a non-empty slice.

[fgmarand]

Problematic case:

• a variable contains a default slice, say base := []int{0,1,2}, meant to be reused without risking being modified
• callers created copy cp := make([]int, len(base); copy(cp, base)
• now caller adds what they want to cp: cp = append(cp, 3, 4) and linter triggers.

The linter complains because there was an append to that non-empty slice, but it has to be non-empty.