Refactoring "parameter can be declared as value" introduces bugs : RSRP-75982

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Project	ReSharper
Priority	Normal
Type	Bug
Fix versions	4.1
State	Fixed
Assignee	Evgeny Pasynkov
Subsystem	No subsystem
Affected versions	No Affected versions
Fixed in build	5.0.1612.107

Created by Ron Gross
3 years ago (28 Jul 2008 13:23)
Updated by Ron Gross
3 years ago (29 Jul 2008 14:05)
Jira: RSRP-75982
(history, comments)

RSRP-75982 Refactoring "parameter can be declared as value" introduces bugs

Issue is visible to: All Users

The version is 4.0.819.19

I applied this refactoring and it introduced bugs - a method can wait for external modification of a value by another thread.

private void Foo()
{
bool b = false;
new Thread((ThreadStart)delegate { b = true;}).Start();
WaitForBool(ref b);
}

private void WaitForBool(ref bool b)
{
while (!b)
{
Thread.Sleep(1000);
}
}

See
http://qimmortal.blogspot.com/2008/07/my-arrogance-in-finding-bugs.html

Issue was closed

Ilya Ryzhenkov

28 Jul 2008 15:22

3 years ago

It turns out that this suggestion can never be triggered for value types?

Ron Gross

28 Jul 2008 18:35

3 years ago

I guess so, unfortunately (barring global analysis).

Vladimir Reshetnikov

29 Jul 2008 13:47

3 years ago

The same problem for reference types:

class A
{
    private void Foo()
    {
        string b = null;
        new Thread((ThreadStart)delegate { b = ""; }).Start();
        WaitForString(ref b);
    }

    private void WaitForString(ref string b)
    {
        while (b==null)
        { Thread.Sleep(1000); }

    }
}

Ron Gross

29 Jul 2008 14:05

3 years ago

Crap.

Too bad, in most cases it does look like a useful refactor. Can it be categorized as a different class of hint ? (something to urge the developer to pay more attention when he applies it)