Package nilness inspects the control-flow graph of an SSA function
and reports errors such as nil pointer dereferences and degenerate
nil pointer comparisons.
Analyzer nilness
nilness: check for redundant or impossible nil comparisons
The nilness checker inspects the control-flow graph of each function in
a package and reports nil pointer dereferences, degenerate nil
pointers, and panics with nil values. A degenerate comparison is of the form
x==nil or x!=nil where x is statically known to be nil or non-nil. These are
often a mistake, especially in control flow related to errors. Panics with nil
values are checked because they are not detectable by
if r := recover(); r != nil {
This check reports conditions such as:
if f == nil { // impossible condition (f is a function)
}
and:
p := &v
...
if p != nil { // tautological condition
}
and:
if p == nil {
print(*p) // nil dereference
}
and:
if p == nil {
panic(p)
}
Sometimes the control flow may be quite complex, making bugs hard
to spot. In the example below, the err.Error expression is
guaranteed to panic because, after the first return, err must be
nil. The intervening loop is just a distraction.
...
err := g.Wait()
if err != nil {
return err
}
partialSuccess := false
for _, err := range errs {
if err == nil {
partialSuccess = true
break
}
}
if partialSuccess {
reportStatus(StatusMessage{
Code: code.ERROR,
Detail: err.Error(), // "nil dereference in dynamic method call"
})
return nil
}
...