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Date: Sat, 22 Oct 2022 16:36:13 +0800
Message-ID: <CAD8EyY2ZPtpid-M3LdgrJ03BR7vHst544EOxLMihkYc2oAdAqw@mail.gmail.com>
Subject: Unexpected behavior of `gdb.PARAM_INTEGER` and `gdb.PARAM_UINTEGER` parameter
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Hi,

I've noticed that if we use Python API to create a `gdb.PARAM_INTEGER` or
`gdb.PARAM_UINTEGER` parameter this way:

```
$ cat test.py

import gdb
class ExampleParam(gdb.Parameter):
    def __init__ (self, name):
        super(ExampleParam, self).__init__ (name, gdb.COMMAND_DATA,
gdb.PARAM_INTEGER)
        self.value =3D 0
        self.saved_value =3D True

    def get_set_string (self):
        print(self.value)
        return "Set to %r" % self.value

ExampleParam("example=E2=80=9D)
```

According to the docs here:
https://sourceware.org/gdb/onlinedocs/gdb/Parameters-In-Python.html, `0`
should be interpreted to mean "unlimited", so I expected that when a
`gdb.PARAM_INTEGER` or `gdb.PARAM_UINTEGER` parameter=E2=80=99s value is
"unlimited" in GDB, then the value in Python will be interpreted to 0.

But somehow, GDB interprets `None` to mean "unlimited" for that parameter
we created:

```
$ gdb -q -nx -ex 'source test.py=E2=80=99
(gdb) show example
The current value of 'example' is "unlimited=E2=80=9D.
(gdb) pi gdb.parameter("example") is None
True
(gdb) set example unlimited
None
Set to None
(gdb) pi gdb.parameter("example") is None
True
(gdb) show example
The current value of 'example' is "unlimited".
(gdb) set example 0
None
Set to None
(gdb) pi gdb.parameter("example") is None
True
(gdb) show example
The current value of 'example' is "unlimited".
```

You can notice that GDB set the value of the `example` to `None` instead of
`0`.

Is this the expected result?

My GDB version is GNU gdb (Ubuntu 12.0.90-0ubuntu1) 12.0.90, and I'm on
Ubuntu 22.04.1 LTS.

Best Regards,
Alan Li

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