AssemblyAttributeAnalyzer¶

AssemblyAttributeAnalyzer<TItem> is the base class for analyzers that scan assembly-level attributes ([assembly: ...]) and report diagnostics based on the extracted data.

Quick Start¶

[DiagnosticAnalyzer(LanguageNames.CSharp)]
[Reports("DSDT001", "Required environment variable not set",
    Message = "Environment variable '{0}' is not set",
    Category = "DevTools",
    Severity = DiagnosticSeverity.Warning)]
[Reports("DSDT002", "Optional environment variable not set",
    Message = "Optional environment variable '{0}' is not set",
    Category = "DevTools",
    Severity = DiagnosticSeverity.Info)]
public sealed class RequiresEnvAnalyzer : AssemblyAttributeAnalyzer<RequiredEnvVar>
{
    protected override string AttributeFullyQualifiedName =>
        "MyApp.RequiresEnvAttribute";

    protected override bool TryExtractItem(
        ValidAttribute attribute, Location location, out RequiredEnvVar item)
    {
        var name = attribute.ConstructorArg<string>(0).OrNull();
        if (name == null) { item = default; return false; }

        var optional = attribute.NamedArg<bool>("Optional").OrDefault(false);
        item = new RequiredEnvVar(name, optional, location);
        return true;
    }

    protected override void Analyze(
        CompilationAnalysisContext context, ImmutableArray<RequiredEnvVar> items)
    {
        foreach (var required in items)
        {
            var rule = required.IsOptional ? GetRule(1) : GetRule(0);
            context.ReportDiagnostic(Diagnostic.Create(
                rule, required.Location, required.Name));
        }
    }
}

How It Works¶

Annotate with one or more [Reports] attributes (multi-diagnostic support)
The base class handles Initialize, ConfigureGeneratedCodeAnalysis, EnableConcurrentExecution, and SupportedDiagnostics
On compilation, scans assembly attributes matching AttributeFullyQualifiedName
Projects each match through ValidAttribute and calls TryExtractItem
Passes all successfully extracted items to Analyze in a single batch

Abstract Members¶

Member	Description
`AttributeFullyQualifiedName`	Fully qualified metadata name of the attribute to scan (e.g., `"MyApp.RequiresToolAttribute"`)
`TryExtractItem(attribute, location, out item)`	Extract a model from each matching attribute. Return `false` to skip.
`Analyze(context, items)`	Evaluate all extracted items and report diagnostics.

Properties & Methods¶

Member	Type	Description
`SupportedDiagnostics`	`ImmutableArray<DiagnosticDescriptor>`	All descriptors from `[Reports]` attributes
`GetRule(index)`	`DiagnosticDescriptor`	Get descriptor by declaration order (0-based)

Multiple [Reports] Attributes¶

Each [Reports] attribute declares a diagnostic descriptor. Access them by index matching the declaration order on the class:

[Reports("DSDT020", "Tool not installed", ...)]     // GetRule(0)
[Reports("DSDT021", "Tool version mismatch", ...)]  // GetRule(1)
[Reports("DSDT022", "Tool manifest missing", ...)]  // GetRule(2)
public sealed class RequiresToolAnalyzer : AssemblyAttributeAnalyzer<RequiredTool>
{
    protected override void Analyze(
        CompilationAnalysisContext context, ImmutableArray<RequiredTool> items)
    {
        // ...
        context.ReportDiagnostic(Diagnostic.Create(
            GetRule(0), location, toolName));  // DSDT020
    }
}

Comparison with SymbolAnalyzer¶

	`SymbolAnalyzer<TSymbol>`	`AssemblyAttributeAnalyzer<TItem>`
Scope	Per-symbol (`RegisterSymbolAction`)	Compilation-level (`RegisterCompilationAction`)
Trigger	Individual symbols	Assembly-level attributes
[Reports]	Single	One or more (`AllowMultiple = true`)
Item extraction	Automatic (attribute match)	Manual via `TryExtractItem`
Analysis	`ShouldReport` returns bool	`Analyze` has full control

When to Use¶

Use AssemblyAttributeAnalyzer when your diagnostics are driven by assembly-level attributes like:

[assembly: RequiresTool("dotnet-ef", Version = "9.*")]
[assembly: RequiresEnv("DATABASE_URL")]
[assembly: Convention(RequireReadme = true)]

For per-symbol analysis (classes, methods, fields with attributes), use SymbolAnalyzer instead.