Extending password entry leads to panic when password revealer is clicked

[nick-remeeting]

Describe the bug:

I want users to be able to submit a username and password with a keypress (enter/return). Following the excellent tutorial on handling keypresses, I was able to do so. However, if the user clicks the password revealer, the app panics due to a segfault:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x41a8d2f]

goroutine 18 [running]:
fyne.io/fyne/v2/internal/app.(*FocusManager).Focus(0x0, 0x4409d00, 0xc000083080, 0x0)
	/Users/nick/go/src/fyne.io/fyne/v2/internal/app/focus_manager.go:25 +0x4f
fyne.io/fyne/v2/internal/driver/glfw.(*glCanvas).Focus(0xc0000b0000, 0x4409d00, 0xc000083080)
	/Users/nick/go/src/fyne.io/fyne/v2/internal/driver/glfw/canvas.go:88 +0x196
fyne.io/fyne/v2/widget.(*passwordRevealer).Tapped(0xc00008e280, 0xc0005748e0)
	/Users/nick/go/src/fyne.io/fyne/v2/widget/entry_password.go:49 +0xc8
fyne.io/fyne/v2/internal/driver/glfw.(*window).mouseClicked.func7()
	/Users/nick/go/src/fyne.io/fyne/v2/internal/driver/glfw/window.go:791 +0x38
fyne.io/fyne/v2/internal/driver/glfw.(*window).runEventQueue(0xc0000a2000)
	/Users/nick/go/src/fyne.io/fyne/v2/internal/driver/glfw/window.go:1242 +0x7a
created by fyne.io/fyne/v2/internal/driver/glfw.(*gLDriver).createWindow.func1
	/Users/nick/go/src/fyne.io/fyne/v2/internal/driver/glfw/window.go:1266 +0x10d

It seems that embedding and using an entry with the password revealer causes it to panic on click. I am not sure if this also happens for other ActionItems; I have only tested it in this one case.

To Reproduce:

Run the example code and click each password revealer. The first two (which are not extended/embedded) work fine, but the second two (which are extended/embedded) both cause a panic on click.

Screenshots:

Example code:

In this example code I don't add any functions to the extended entry -- in the real app there would be a method to handle key presses.

package main

import (
	"fyne.io/fyne/v2/app"
	"fyne.io/fyne/v2/container"
	"fyne.io/fyne/v2/widget"
)

type myPasswordEntry struct {
	widget.Entry
}

func newMyPasswordEntry() *myPasswordEntry {
	entry := &myPasswordEntry{
		widget.Entry{
			Password: true,
		},
	}
	entry.ExtendBaseWidget(entry)
	return entry
}

type myOtherPasswordEntry struct {
	*widget.Entry
}

func newMyOtherPasswordEntry() *myOtherPasswordEntry {
	entry := &myOtherPasswordEntry{
		&widget.Entry{
			Password: true,
		},
	}
	entry.ExtendBaseWidget(entry)
	return entry
}

func main() {
	myApp := app.New()
	window := myApp.NewWindow("Example")

	passwordEntry0 := widget.NewPasswordEntry()
	passwordEntry1 := &widget.Entry{Password: true}
	passwordEntry2 := newMyPasswordEntry()
	passwordEntry3 := newMyOtherPasswordEntry()

	passwordEntry0.SetPlaceHolder("Password revealer works")
	passwordEntry1.SetPlaceHolder("This one works too")
	passwordEntry2.SetPlaceHolder("This one crashes")
	passwordEntry3.SetPlaceHolder("This one crashes as well")

	vBox := container.NewVBox(passwordEntry0, passwordEntry1, passwordEntry2, passwordEntry3)

	window.SetContent(vBox)

	window.ShowAndRun()
}

Device (please complete the following information):

• OS: MacOS
• Version: 11.2.1
• Go version: 1.15.7
• Fyne version: 2.0.0

[Jacalz]

I have not looked at the bug yet, but as a workaround, fyne 2.0.0 and later has the entry.OnSubmit function that you can use directly without having to extend the widget.

[Jacalz]

Just a thought. Does it work if you set entry.Password = true after the entry.ExtendBaseWidget(entry) call in the newMyPasswordEntry function (instead of passing the whole entry in the struct)?

like this, I mean:

entry := &myPasswordEntry{}
entry.ExtendBaseWidget(entry)
entry.Password = true
return entry

This was just a thought I had because I know that extending things in Go can be a bit tricky at times. Might not make any difference.

[andydotxyz]

This may have been fixed by recent focus work, but I suspect there is a line in our password widget that forgot it may be extended.

[nick-remeeting]

@Jacalz : I tried your suggestions. Using the entry.OnSubmitted() method works! I'll be using this method in my app, thanks!

I also tried assigning the entry.Password attribute after the entry.ExtendBaseWidget() call as you suggest, and encounter the same bug (I get the same panic as before).

@andydotxyz : Thanks for the info.

Thank you both for your assistance and please do let me know if I can help tracking this bug down.

[andydotxyz]

Fixed on develop, will be in 2.0.1