Fix: wrong reference count after invalid Map[key] = value

[Wi1l-B0t]

Description

When set a value to map, The old value reference removed in Line 55 or the new key reference added in Line 57.

But if Line 60 throws a InvalidOperationException, the reference count will be wrong,
because the ReferenceCounter has been updated, but the internal collection not.

neo/src/Neo.VM/Types/Map.cs

Lines 52 to 62 in 6c7f6c4

	if (ReferenceCounter != null)
	{
	if (dictionary.TryGetValue(key, out StackItem? old_value))
	ReferenceCounter.RemoveReference(old_value, this);
	else
	ReferenceCounter.AddReference(key, this);
	if (value is CompoundType { ReferenceCounter: null })
	{
	throw new InvalidOperationException("Can not set a Map without a ReferenceCounter.");
	}
	ReferenceCounter.AddReference(value, this);

Type of change

• Optimization (the change is only an optimization)
• Style (the change is only a code style for better maintenance or standard purpose)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[roman-khimov]

#3693, please...

IIUC correctly bytecode triggering this will make VM fail, so the exact count is not much relevant in this case. But worth fixing anyway.

[shargon]

Why don't use the same foreach?

[Wi1l-B0t]

Why don't use the same foreach?

For example:
The _array has 2 items, and the first added, but the second is invalid.
Line 86 throws a InvalidOperationException, and then the ReferenceCounter is wrong.

[Wi1l-B0t]

Why don't use the same foreach?

This issue shouldn't be triggered in real environments, but it’s better to be cautious.

[shargon]

If throw an exceptiotge execution is halted

[Wi1l-B0t]

If throw an exceptiotge execution is halted

Make it more rigorous.

[shargon]

If throw an exceptiotge execution is halted

Make it more rigorous.

Slower without need

[Wi1l-B0t]

If throw an exceptiotge execution is halted

Make it more rigorous.

Slower without need

It's so trivial.
Few items in array in most cases.
And after the first foreach, the code will be hot(cache and branch predictor), it should be fast enough.

[shargon]

No need, it will be a fault, have no sense