'RegisterSymbolAction' for 'Property' doesn't run at all on partial properties with attributes on both definition and implementation parts

[Sergio0694]

Version Used: 4.12.0-3.24558.5 (21192bf)

Steps to Reproduce:

1. Clone https://github.com/CommunityToolkit/dotnet
2. Checkout dev/more-analyzers (or Add more analyzers, enable unit tests for partial properties CommunityToolkit/dotnet#1010)
3. Remove the [Ignore] from InvalidPartialPropertyLevelObservablePropertyAttributeAnalyzer_OnImplementedProperty_GeneratedByAnotherGenerator_Warns
4. Put a breakpoint in the RegisterSymbolAction callback in InvalidPartialPropertyLevelObservablePropertyAttributeAnalyzer
5. Run the test
6. Verify that the callback is never executed
7. Comment out the [GeneratedCode] attribute on the partial property implementation in that test
8. Run the test again
9. Verify the callback is now hit (??!)

Expected Behavior:

The RegisterSymbolAction callback should work as expected in both cases.

Actual Behavior:

The RegisterSymbolAction callback is apparently not called at all if you leave the attribute on the implementation part.

[Sergio0694]

cc. @RikkiGibson. I found this in CommunityToolkit/dotnet#1010.

[Youssef1313]

Somewhat overlaps with #69543

[Youssef1313]

It might not be exactly #69543.

I didn't debug, but just looking around in the code.

roslyn/src/Compilers/Core/Portable/SourceGeneration/GeneratedCodeUtilities.cs

Lines 29 to 43 in f614346

	// GeneratedCodeAttribute can only be applied once on a symbol.
	// For partial symbols with more than one definition, we must treat them as non-generated code symbols.
	if (symbol.DeclaringSyntaxReferences.Length > 1)
	{
	return false;
	}
	foreach (var attribute in symbol.GetAttributes())
	{
	if (generatedCodeAttribute.Equals(attribute.AttributeClass))
	{
	return true;
	}
	}
	}

This should not be considering GeneratedCodeAttribute if the symbol has multiple syntax refs.

However, I see this in property symbol:

roslyn/src/Compilers/CSharp/Portable/Symbols/Source/SourcePropertySymbolBase.cs

Lines 534 to 540 in f614346

	public override ImmutableArray<SyntaxReference> DeclaringSyntaxReferences
	{
	get
	{
	return ImmutableArray.Create(_syntaxRef);
	}
	}

This may be outdated code?

[RikkiGibson]

However, I see this in property symbol

I think DeclaringSyntaxReferences is implemented as expected. It is consistent with methods. Each part symbol has a single DeclaringSyntaxReference, and you need to get that part symbol to get the appropriate SyntaxReference for it.

The symbol.DeclaringSyntaxReferences.Length > 1 seems valid for partial types, but, additional work is probably needed here to simply check "is this a partial method/property with multiple declarations."

[Youssef1313]

Makes sense. Thanks @RikkiGibson

[Sergio0694]

As a temporary workaround I ended up enabling the analyzer to run on generated code too, seems to do the trick 😅