PANIC=Format method: runtime error: invalid memory address or nil pointer dereference with go 1.17 about pretty HOT 8 CLOSED

Yes,

also getting a panic for time pointers

%!v(PANIC=Format method: value method time.Time.GoString called using nil *Time pointer)

with a *time.Time in a struct that = nil

Go 1.17.6
Prettty v0.3.0

from pretty.

Some relevant info in https://go.dev/issue/20995.

from pretty.

Same issue. How to fix ?

from pretty.

Still observing this on Go 1.18.5.

from pretty.

So the go dev issue 20995 says that the workaround (while a bit ugly) is to essentially check to see if you have a pointer, and whether the Elem of the pointer has the method:

if fieldType.Kind() == reflect.Ptr && field.IsNil() {
	// Method defined on a value receiver.
	if _, ok := fieldType.Elem().MethodByName("Check"); ok {
		continue // Ignore since value can't be retrieved from nil pointer
	}
}

Essentially you are saying "oh, I have a nil pointer, let me check if the method is defined on the Value (non-pointer) of this type".
I'm not sure if that means all of the kr/pretty code that says "you have a custom formatter" then needs to do this check (but the custom formatter is defined on a value type but I have a nil pointer)
It doesn't seem bad to just say "ignore custom formatters if you have a nil pointer"

from pretty.

We fixed this in our canonical fork at canonical@771f4dc (see discussion at canonical#1). It's fixed in a similar way to how fmt does when calling GoString and other user-defined methods. I've also created a pull request here with the same fix: #87

from pretty.

Shouldn't there be a new proper release with this fix integrated?

from pretty.

Shouldn't there be a new proper release with this fix integrated?

Yes indeed. Just tagged v0.3.1. Thank you.

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