Make 'AllowsUnsafeBlocks' analyzer target attributes

src/ComputeSharp.D2D1.SourceGenerators/Diagnostics/Analyzers/MissingAllowUnsafeBlocksCompilationOptionAnalyzer.cs

@@ -13,7 +13,7 @@ public sealed class MissingAllowUnsafeBlocksCompilationOptionAnalyzer : MissingA
     /// Creates a new <see cref="MissingAllowUnsafeBlocksCompilationOptionAnalyzer"/> instance.
     /// </summary>
     public MissingAllowUnsafeBlocksCompilationOptionAnalyzer()
-        : base(MissingAllowUnsafeBlocksOption)
+        : base(MissingAllowUnsafeBlocksOption, "ComputeSharp.D2D1.D2DGeneratedPixelShaderDescriptorAttribute")
     {
     }
 }

src/ComputeSharp.D2D1.SourceGenerators/Diagnostics/DiagnosticDescriptors.cs

@@ -944,19 +944,18 @@ partial class DiagnosticDescriptors
     /// <summary>
     /// Gets a <see cref="DiagnosticDescriptor"/> for when the <c>AllowUnsafeBlocks</c> option is not set.
     /// <para>
-    /// Format: <c>"Unsafe blocks must be enabled for the source generators to emit valid code (add &lt;AllowUnsafeBlocks&gt;true&lt;/AllowUnsafeBlocks&gt; to your .csproj/.props file)"</c>.
+    /// Format: <c>"Using [D2DGeneratedPixelShaderDescriptor] requires unsafe blocks being enabled, as they needed by the source generators to emit valid code (add &lt;AllowUnsafeBlocks&gt;true&lt;/AllowUnsafeBlocks&gt; to your .csproj/.props file)"</c>.
     /// </para>
     /// </summary>
     public static readonly DiagnosticDescriptor MissingAllowUnsafeBlocksOption = new(
         id: "CMPSD2D0064",
         title: "Missing 'AllowUnsafeBlocks' compilation option",
-        messageFormat: "Unsafe blocks must be enabled for the source generators to emit valid code (add <AllowUnsafeBlocks>true</AllowUnsafeBlocks> to your .csproj/.props file)",
+        messageFormat: "Using [D2DGeneratedPixelShaderDescriptor] requires unsafe blocks being enabled, as they needed by the source generators to emit valid code (add <AllowUnsafeBlocks>true</AllowUnsafeBlocks> to your .csproj/.props file)",
         category: "ComputeSharp.D2D1.Shaders",
         defaultSeverity: DiagnosticSeverity.Error,
         isEnabledByDefault: true,
-        description: "Unsafe blocks must be enabled for the source generators to emit valid code (the <AllowUnsafeBlocks>true</AllowUnsafeBlocks> option must be set in the .csproj/.props file).",
-        helpLinkUri: "https://github.com/Sergio0694/ComputeSharp",
-        customTags: WellKnownDiagnosticTags.CompilationEnd);
+        description: "Unsafe blocks must be enabled when using [D2DGeneratedPixelShaderDescriptor] for the source generators to emit valid code (the <AllowUnsafeBlocks>true</AllowUnsafeBlocks> option must be set in the .csproj/.props file).",
+        helpLinkUri: "https://github.com/Sergio0694/ComputeSharp");
 
     /// <summary>
     /// Gets a <see cref="DiagnosticDescriptor"/> for when a pixel shader type doesn't have an associated descriptor.

src/ComputeSharp.SourceGeneration.Hlsl/Diagnostics/Analyzers/MissingAllowUnsafeBlocksCompilationOptionAnalyzerBase.cs

@@ -9,7 +9,10 @@ namespace ComputeSharp.SourceGeneration.Diagnostics;
 /// A diagnostic analyzer that generates an error if the <c>AllowUnsafeBlocks</c> compilation option is not set.
 /// </summary>
 /// <param name="diagnosticDescriptor">The <see cref="DiagnosticDescriptor"/> instance to use.</param>
-public abstract class MissingAllowUnsafeBlocksCompilationOptionAnalyzerBase(DiagnosticDescriptor diagnosticDescriptor) : DiagnosticAnalyzer
+/// <param name="generatedShaderDescriptorFullyQualifiedTypeName">The fully qualified type name of the target attribute.</param>
+public abstract class MissingAllowUnsafeBlocksCompilationOptionAnalyzerBase(
+    DiagnosticDescriptor diagnosticDescriptor,
+    string generatedShaderDescriptorFullyQualifiedTypeName) : DiagnosticAnalyzer
 {
     /// <inheritdoc/>
     public sealed override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; } = [diagnosticDescriptor];
@@ -20,13 +23,38 @@ public sealed override void Initialize(AnalysisContext context)
         context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.Analyze | GeneratedCodeAnalysisFlags.ReportDiagnostics);
         context.EnableConcurrentExecution();
 
-        context.RegisterCompilationAction(context =>
+        context.RegisterCompilationStartAction(context =>
         {
-            // Check whether unsafe blocks are available, and emit an error if they are not
-            if (!context.Compilation.IsAllowUnsafeBlocksEnabled())
+            // If unsafe blocks are allowed, we'll never need to emit a diagnostic
+            if (context.Compilation.IsAllowUnsafeBlocksEnabled())
             {
-                context.ReportDiagnostic(Diagnostic.Create(diagnosticDescriptor, location: null));
+                return;
             }
+
+            // Get the symbol for the target attribute type
+            if (context.Compilation.GetTypeByMetadataName(generatedShaderDescriptorFullyQualifiedTypeName) is not { } generatedShaderDescriptorAttributeSymbol)
+            {
+                return;
+            }
+
+            // Check if any types in the compilation are using the trigger attribute
+            context.RegisterSymbolAction(context =>
+            {
+                // Only struct types are possible targets
+                if (context.Symbol is not INamedTypeSymbol { TypeKind: TypeKind.Struct } typeSymbol)
+                {
+                    return;
+                }
+
+                // If the target type is not using the attribute, there's nothing left to do
+                if (!typeSymbol.TryGetAttributeWithType(generatedShaderDescriptorAttributeSymbol, out AttributeData? attribute))
+                {
+                    return;
+                }
+
+                // Emit the error on the attribute use
+                context.ReportDiagnostic(Diagnostic.Create(diagnosticDescriptor, attribute.GetLocation()));
+            }, SymbolKind.NamedType);
         });
     }
 }

src/ComputeSharp.SourceGenerators/Diagnostics/Analyzers/MissingAllowUnsafeBlocksCompilationOptionAnalyzer.cs

@@ -13,7 +13,7 @@ public sealed class MissingAllowUnsafeBlocksCompilationOptionAnalyzer : MissingA
     /// Creates a new <see cref="MissingAllowUnsafeBlocksCompilationOptionAnalyzer"/> instance.
     /// </summary>
     public MissingAllowUnsafeBlocksCompilationOptionAnalyzer()
-        : base(MissingAllowUnsafeBlocksOption)
+        : base(MissingAllowUnsafeBlocksOption, "ComputeSharp.GeneratedComputeShaderDescriptorAttribute")
     {
     }
 }

src/ComputeSharp.SourceGenerators/Diagnostics/DiagnosticDescriptors.cs

@@ -720,19 +720,18 @@ partial class DiagnosticDescriptors
     /// <summary>
     /// Gets a <see cref="DiagnosticDescriptor"/> for when the <c>AllowUnsafeBlocks</c> option is not set.
     /// <para>
-    /// Format: <c>"Unsafe blocks must be enabled for the source generators to emit valid code (add &lt;AllowUnsafeBlocks&gt;true&lt;/AllowUnsafeBlocks&gt; to your .csproj/.props file)"</c>.
+    /// Format: <c>"Using [GeneratedComputeShaderDescriptor] requires unsafe blocks being enabled, as they needed by the source generators to emit valid code (add &lt;AllowUnsafeBlocks&gt;true&lt;/AllowUnsafeBlocks&gt; to your .csproj/.props file)"</c>.
     /// </para>
     /// </summary>
     public static readonly DiagnosticDescriptor MissingAllowUnsafeBlocksOption = new(
         id: "CMPS0052",
         title: "Missing 'AllowUnsafeBlocks' compilation option",
-        messageFormat: "Unsafe blocks must be enabled for the source generators to emit valid code (add <AllowUnsafeBlocks>true</AllowUnsafeBlocks> to your .csproj/.props file)",
+        messageFormat: "Using [GeneratedComputeShaderDescriptor] requires unsafe blocks being enabled, as they needed by the source generators to emit valid code (add <AllowUnsafeBlocks>true</AllowUnsafeBlocks> to your .csproj/.props file)",
         category: "ComputeSharp.Shaders",
         defaultSeverity: DiagnosticSeverity.Error,
         isEnabledByDefault: true,
-        description: "Unsafe blocks must be enabled for the source generators to emit valid code (the <AllowUnsafeBlocks>true</AllowUnsafeBlocks> option must be set in the .csproj/.props file).",
-        helpLinkUri: "https://github.com/Sergio0694/ComputeSharp",
-        customTags: WellKnownDiagnosticTags.CompilationEnd);
+        description: "Unsafe blocks must be enabled when using [GeneratedComputeShaderDescriptor] for the source generators to emit valid code (the <AllowUnsafeBlocks>true</AllowUnsafeBlocks> option must be set in the .csproj/.props file).",
+        helpLinkUri: "https://github.com/Sergio0694/ComputeSharp");
 
     /// <summary>
     /// Gets a <see cref="DiagnosticDescriptor"/> for when a compute shader type doesn't have an associated descriptor.