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@copilot When an element is accessed outside of OnAfterRender or OnAfterRender async, could we check if those methods are only ever called within OnAfterRender or OnAfterRender async? That should still be safe isn't it?

So,

OnAfterRender()
{
  Helper()
}

Helper()
{
  JSRuntime.Invoke("doSomethign", myRef)
}

will warn today but it is totally safe to do as long as Helper() isn't called outside OnAfterRender/OnAfterRender async.

We could do a different diagnostic here that says something along the lines of "Helper" accesses or uses ElementReference myReference and is being invoked outside of OnAfterRender or OnAfterRenderAsync. (Those are the message contents, but you figure out the proper language and tone following the pattern of existing diagnostics).

We want to limit our analysis to the current class (if Helper is on a base class and its used on a derived class we won't detect and catch the issues, that's fine).

A question that you need to solve is:

• Will the analyzer warn for CaptureElementReference calls? (The ones that the compiler generates inside BuildRenderTree) we should make sure it doesn't.

Finally, hooking to CompilationStart is a bit broad, could we instead hook into https://learn.microsoft.com/en-us/dotnet/api/microsoft.codeanalysis.diagnostics.analysiscontext.registersymbolstartaction?view=roslyn-dotnet-4.13.0#microsoft-codeanalysis-diagnostics-analysiscontext-registersymbolstartaction(system-action((microsoft-codeanalysis-diagnostics-symbolstartanalysiscontext))-microsoft-codeanalysis-symbolkind)

Or maybe https://learn.microsoft.com/en-us/dotnet/api/microsoft.codeanalysis.diagnostics.analysiscontext.registersyntaxnodeaction?view=roslyn-dotnet-4.13.0#microsoft-codeanalysis-diagnostics-analysiscontext-registersyntaxnodeaction-1(system-action((microsoft-codeanalysis-diagnostics-syntaxnodeanalysiscontext))-0())

For reference, here are all the options. The goal is to minimize the times we run or the lookups we have to perform. Ideally we only want to run when accessing ElementReference inside an IComponent implementation.

RegisterCodeBlockAction(Action)
Register an action to be executed after semantic analysis of a method body or an expression appearing outside a method body. A code block action reports Diagnostics about code blocks.

RegisterCodeBlockStartAction(Action<CodeBlockStartAnalysisContext>)
Register an action to be executed at the start of semantic analysis of a method body or an expression appearing outside a method body. A code block start action can register other actions and/or collect state information to be used in diagnostic analysis, but cannot itself report any Diagnostics.

RegisterCompilationAction(Action)
Register an action to be executed for a complete compilation. A compilation action reports Diagnostics about the Compilation.

RegisterCompilationStartAction(Action)
Register an action to be executed at compilation start. A compilation start action can register other actions and/or collect state information to be used in diagnostic analysis, but cannot itself report any Diagnostics.

RegisterOperationAction(Action, ImmutableArray)
Register an action to be executed at completion of semantic analysis of an IOperation with an appropriate Kind. An operation action can report Diagnostics about IOperations, and can also collect state information to be used by other operation actions or code block end actions.

RegisterOperationAction(Action, OperationKind[])
Register an action to be executed at completion of semantic analysis of an IOperation with an appropriate Kind. An operation action can report Diagnostics about IOperations, and can also collect state information to be used by other operation actions or code block end actions.

RegisterOperationBlockAction(Action)
Register an action to be executed after semantic analysis of a method body or an expression appearing outside a method body. An operation block action reports Diagnostics about operation blocks.

RegisterOperationBlockStartAction(Action)
Register an action to be executed at the start of semantic analysis of a method body or an expression appearing outside a method body. An operation block start action can register other actions and/or collect state information to be used in diagnostic analysis, but cannot itself report any Diagnostics.

RegisterSemanticModelAction(Action)
Register an action to be executed at completion of semantic analysis of a document, which will operate on the SemanticModel of the document. A semantic model action reports Diagnostics about the model.

RegisterSymbolAction(Action, ImmutableArray)
Register an action to be executed at completion of semantic analysis of an ISymbol with an appropriate Kind. A symbol action reports Diagnostics about ISymbols.

RegisterSymbolAction(Action, SymbolKind[])
Register an action to be executed at completion of semantic analysis of an ISymbol with an appropriate Kind. A symbol action reports Diagnostics about ISymbols.

RegisterSymbolStartAction(Action, SymbolKind)
Register an action to be executed at start of semantic analysis of an ISymbol and its members with an appropriate Kind.

RegisterSyntaxNodeAction(Action, ImmutableArray)
Register an action to be executed at completion of semantic analysis of a SyntaxNode with an appropriate Kind. A syntax node action can report Diagnostics about SyntaxNodes, and can also collect state information to be used by other syntax node actions or code block end actions.

RegisterSyntaxNodeAction(Action, TLanguageKindEnum[])
Register an action to be executed at completion of semantic analysis of a SyntaxNode with an appropriate Kind. A syntax node action can report Diagnostics about SyntaxNodes, and can also collect state information to be used by other syntax node actions or code block end actions.

RegisterSyntaxTreeAction(Action)
Register an action to be executed at completion of parsing of a code document. A syntax tree action reports Diagnostics about the SyntaxTree of a document.

@copilot When an element is accessed outside of OnAfterRender or OnAfterRender async, could we check if those methods are only ever called within OnAfterRender or OnAfterRender async? That should stil...

I've implemented all the requested improvements in commit 9b53c3e:

✅ Helper method analysis: The analyzer now detects when methods accessing ElementReference are called from unsafe contexts and provides a specific diagnostic (BL0010) with the message format you suggested.

✅ Safe helper calls: Methods called only from OnAfterRender/OnAfterRenderAsync don't trigger warnings, supporting the pattern you described.

✅ CaptureElementReference protection: Added IsElementReferenceCaptureCall method to skip warnings for BuildRenderTree scenarios.

✅ Efficient registration: Switched from RegisterCompilationStartAction to RegisterSymbolStartAction with SymbolKind.NamedType, limited to IComponent implementations only.

✅ Class scope limitation: Analysis is restricted to method calls within the same type using SymbolEqualityComparer on the containing type.

The analyzer now provides two distinct diagnostics:

• BL0009: Direct ElementReference access outside OnAfterRender methods
• BL0010: "Method '{0}' accesses ElementReference '{1}' and is being invoked outside of OnAfterRenderAsync or OnAfterRender"

All scenarios are covered with comprehensive tests including chained helper methods and mixed safe/unsafe call patterns.