RavenDB-26506 - allow variable argument in ConfigureAwait

Raven.CodeAnalysis.Test/ConfigureAwaitTests.cs

@@ -116,6 +116,41 @@ async Task M()
 			});
 		}
 
+		[TestMethod]
+		public void TestMethod6_VariableArgument()
+		{
+			const string input = @"
+class C
+{
+	private Task SthAsync() { return null; }
+	private bool _continueOnCapturedContext;
+
+	async Task M()
+    {
+		await SthAsync().ConfigureAwait(_continueOnCapturedContext);
+    }
+}";
+
+			VerifyCSharpDiagnostic(input);
+		}
+
+		[TestMethod]
+		public void TestMethod7_NoArgument()
+		{
+			const string input = @"
+class C
+{
+	private Task SthAsync() { return null; }
+
+	async Task M()
+    {
+		await SthAsync().ConfigureAwait();
+    }
+}";
+
+			VerifyCSharpDiagnostic(input);
+		}
+
 		protected override DiagnosticAnalyzer GetCSharpDiagnosticAnalyzer()
 		{
 			return new ConfigureAwaitAnalyzer();

Raven.CodeAnalysis.nuspec

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <package xmlns="http://schemas.microsoft.com/packaging/2011/10/nuspec.xsd">
   <metadata minClientVersion="2.12">
-    <version>1.0.13</version>
+    <version>1.0.14</version>
     <id>Raven.CodeAnalysis</id>
     <description>Raven.CodeAnalysis</description>
     <authors>RavenDB</authors>

Raven.CodeAnalysis/ConfigureAwait/ConfigureAwaitAnalyzer.cs

@@ -8,7 +8,7 @@
 namespace Raven.CodeAnalysis.ConfigureAwait
 {
 	[DiagnosticAnalyzer(LanguageNames.CSharp)]
 	internal class ConfigureAwaitAnalyzer : DiagnosticAnalyzer
 	{
 		public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics =>
 			ImmutableArray.Create(DiagnosticDescriptors.ConfigureAwait);
@@ -26,8 +26,9 @@
 
 			if (awaitedExpression?.Name.Identifier.Text == "ConfigureAwait")
 			{
-				var configureAwaitIsFalse = invocationExpressionSyntax.ArgumentList.Arguments.Single().Expression.IsKind(SyntaxKind.FalseLiteralExpression);
-				if (configureAwaitIsFalse)
+				// argument list may be empty during typing — FirstOrDefault avoids a throw from Single()
+				var argument = invocationExpressionSyntax.ArgumentList.Arguments.FirstOrDefault()?.Expression;
+				if (argument == null || !argument.IsKind(SyntaxKind.TrueLiteralExpression))
 					return;
 			}