[RGen] Add analyzer rules for async methods in a class. (#23774)

Ensure that:

1. If a method can be async, that is marked as such (warning).
2. Make sure marked async methods return void (error).
3. Make sure marked async methods have a delegate (error).
4. Make sure that Async methods have diff async names if the parameters
are the same (error).

The tests showed a number of bugs in the async generation when we use
the async flag with no parameters. Those got fixed.

---------

Co-authored-by: GitHub Actions Autoformatter <[email protected]>

Author: mandel-macaque

src/rgen/Microsoft.Macios.Bindings.Analyzer/Resources.Designer.cs

@@ -469,4 +469,69 @@
         <value>Duplicate selector</value>
     </data>
 
+    <!-- RBI0035 -->
+    
+    <data name="RBI0035Description" xml:space="preserve">
+        <value>A method marked as an async method should have void as its return type.</value>
+    </data>
+    <data name="RBI0035MessageFormat" xml:space="preserve">
+        <value>The method '{0}' was marked as async but its return type is not void</value>
+        <comment>{0} is the name of the method.</comment>
+    </data>
+    <data name="RBI0035Title" xml:space="preserve">
+        <value>Async method not returning void</value>
+    </data>
+    
+    <!-- RBI0036 -->
+    
+    <data name="RBI0036Description" xml:space="preserve">
+        <value>A method marked as an async method should have at least one parameter that is a delegate.</value>
+    </data>
+    <data name="RBI0036MessageFormat" xml:space="preserve">
+        <value>The method '{0}' was marked as async but has 0 parameters when at least a single delegate parameter is required</value>
+        <comment>{0} is the name of the method.</comment>
+    </data>
+    <data name="RBI0036Title" xml:space="preserve">
+        <value>No parameters in async method</value>
+    </data>
+    
+    <!-- RBI0037 -->
+    
+    <data name="RBI0037Description" xml:space="preserve">
+        <value>A method marked as an async method should have its last parameter be a delegate.</value>
+    </data>
+    <data name="RBI0037MessageFormat" xml:space="preserve">
+        <value>The method '{0}' was marked as async but its last parameter is not a delegate</value>
+        <comment>{0} is the name of the method.</comment>
+    </data>
+    <data name="RBI0037Title" xml:space="preserve">
+        <value>Last parameter is not a delegate</value>
+    </data>
+    
+    <!-- RBI0038 -->
+    
+    <data name="RBI0038Description" xml:space="preserve">
+        <value>A method that could be async was not marked as async.</value>
+    </data>
+    <data name="RBI0038MessageFormat" xml:space="preserve">
+        <value>The method '{0}' was not marked as async but it can be</value>
+        <comment>{0} is the name of the method.</comment>
+    </data>
+    <data name="RBI0038Title" xml:space="preserve">
+        <value>Possible async method missing async flag</value>
+    </data>
+    
+    <!-- RBI0039 -->
+    
+    <data name="RBI0039Description" xml:space="preserve">
+        <value>Two methods marked as async will result in the same async name.</value>
+    </data>
+    <data name="RBI0039MessageFormat" xml:space="preserve">
+        <value>The async name '{0}' used by '{1}' is already used by '{2}'</value>
+        <comment>{0} is the name of the async method, {1} is the name of the sync method and {2} is the name of the first ocurrance.</comment>
+    </data>
+    <data name="RBI0039Title" xml:space="preserve">
+        <value>Duplicated async name</value>
+    </data>
+    
 </root>

src/rgen/Microsoft.Macios.Bindings.Analyzer/Resources.resx

@@ -526,4 +526,79 @@ public static class RgenDiagnostics {
 		description: new LocalizableResourceString (nameof (Resources.RBI0034Description), Resources.ResourceManager,
 			typeof (Resources))
 	);
+
+	/// <summary>
+	/// Diagnostic descriptor for when a marked async method has not void return. 
+	/// </summary>
+	internal static readonly DiagnosticDescriptor RBI0035 = new (
+		"RBI0035",
+		new LocalizableResourceString (nameof (Resources.RBI0035Title), Resources.ResourceManager, typeof (Resources)),
+		new LocalizableResourceString (nameof (Resources.RBI0035MessageFormat), Resources.ResourceManager,
+			typeof (Resources)),
+		"Usage",
+		DiagnosticSeverity.Error,
+		isEnabledByDefault: true,
+		description: new LocalizableResourceString (nameof (Resources.RBI0035Description), Resources.ResourceManager,
+			typeof (Resources))
+	);
+
+	/// <summary>
+	/// Diagnostic descriptor for when a marked async method has no parameters. 
+	/// </summary>
+	internal static readonly DiagnosticDescriptor RBI0036 = new (
+		"RBI0036",
+		new LocalizableResourceString (nameof (Resources.RBI0036Title), Resources.ResourceManager, typeof (Resources)),
+		new LocalizableResourceString (nameof (Resources.RBI0036MessageFormat), Resources.ResourceManager,
+			typeof (Resources)),
+		"Usage",
+		DiagnosticSeverity.Error,
+		isEnabledByDefault: true,
+		description: new LocalizableResourceString (nameof (Resources.RBI0036Description), Resources.ResourceManager,
+			typeof (Resources))
+	);
+
+	/// <summary>
+	/// Diagnostic descriptor for when a marked async method has no delegate as the last parameter. 
+	/// </summary>
+	internal static readonly DiagnosticDescriptor RBI0037 = new (
+		"RBI0037",
+		new LocalizableResourceString (nameof (Resources.RBI0037Title), Resources.ResourceManager, typeof (Resources)),
+		new LocalizableResourceString (nameof (Resources.RBI0037MessageFormat), Resources.ResourceManager,
+			typeof (Resources)),
+		"Usage",
+		DiagnosticSeverity.Error,
+		isEnabledByDefault: true,
+		description: new LocalizableResourceString (nameof (Resources.RBI0037Description), Resources.ResourceManager,
+			typeof (Resources))
+	);
+
+	/// <summary>
+	/// Diagnostic descriptor for when a method that could be async was not marked. 
+	/// </summary>
+	internal static readonly DiagnosticDescriptor RBI0038 = new (
+		"RBI0038",
+		new LocalizableResourceString (nameof (Resources.RBI0038Title), Resources.ResourceManager, typeof (Resources)),
+		new LocalizableResourceString (nameof (Resources.RBI0038MessageFormat), Resources.ResourceManager,
+			typeof (Resources)),
+		"Usage",
+		DiagnosticSeverity.Warning,
+		isEnabledByDefault: true,
+		description: new LocalizableResourceString (nameof (Resources.RBI0038Description), Resources.ResourceManager,
+			typeof (Resources))
+	);
+
+	/// <summary>
+	/// Diagnostic descriptor for when two methods with the same parameters have the same async name. 
+	/// </summary>
+	internal static readonly DiagnosticDescriptor RBI0039 = new (
+		"RBI0039",
+		new LocalizableResourceString (nameof (Resources.RBI0039Title), Resources.ResourceManager, typeof (Resources)),
+		new LocalizableResourceString (nameof (Resources.RBI0039MessageFormat), Resources.ResourceManager,
+			typeof (Resources)),
+		"Usage",
+		DiagnosticSeverity.Error,
+		isEnabledByDefault: true,
+		description: new LocalizableResourceString (nameof (Resources.RBI0039Description), Resources.ResourceManager,
+			typeof (Resources))
+	);
 }