fixes crash when resolving types in anonymous function expressions declaration (#331)

Author: adrianoc

Cecilifier.Core.Tests/Tests/Unit/Miscellaneous.cs

@@ -347,10 +347,11 @@ public void TypeDeclarationResolverTests(string code)
             }
         }
 
-        [Test, Ignore("Issue #331")]
-        public void Lambda_With_DefaultParameter()
+        [TestCase("var f = (int i) => i + 1;")]
+        [TestCase("System.Func<int, int> f = (int i) => i + 1;")]
+        public void SimpleLambda_ToDelegateConversion_DoesNotCrash(string code)
         {
-            var ctx = RunCecilifier("var f = (int i = 41) => i + 1;");
+            var ctx = RunCecilifier(code);
             Assert.Pass();
         }
 

Cecilifier.Core.Tests/Tests/Unit/NonCapturingLambdaProcessorTests.cs

@@ -49,7 +49,7 @@ public void Conversion_FromDelegates_OtherThanFuncAndAction_AreReported(string s
         {
             var context = RunProcessorOn(source);
             Assert.That(context.Output, Does.Not.Contains("//Synthetic method for lambda expression: i => i + 1"));
-            Assert.That(context.Output, Contains.Substring("//Lambda to delegates conversion is only supported for Func<> and Action<>"));
+            Assert.That(context.Output, Contains.Substring("#warning Lambda to delegates conversion is only supported for Func<> and Action<>"));
         }
 
         [TestCase("using System; class Foo { void M(Func<int, int> a) { M(x => x + 1); } }", TestName = "Expression")]

Cecilifier.Core/AST/NonCapturingLambdaProcessor.cs

@@ -22,7 +22,7 @@ public static void InjectSyntheticMethodsForNonCapturingLambdas(IVisitorContext
 
                 if (!IsValidConversion(context, lambda))
                 {
-                    context.WriteComment("Lambda to delegates conversion is only supported for Func<> and Action<>");
+                    context.EmitWarning($"Lambda to delegates conversion is only supported for Func<> and Action<>: {node.HumanReadableSummary()}", node);
                     continue;
                 }
 

Cecilifier.Core/AST/SyntaxWalkerBase.cs

@@ -374,7 +374,8 @@ protected static void WriteCecilExpression(IVisitorContext context, string value
 
         protected string ResolveExpressionType(ExpressionSyntax expression)
         {
-            var type = Context.GetTypeInfo(expression).Type.EnsureNotNull();
+            var typeInfo = Context.GetTypeInfo(expression);
+            var type = (typeInfo.Type ?? typeInfo.ConvertedType).EnsureNotNull();
             return Context.TypeResolver.Resolve(type);
         }
 
@@ -941,11 +942,16 @@ private static IEnumerable<string> ProcessNormalMemberAttribute(IVisitorContext
 
         protected void LogUnsupportedSyntax(SyntaxNode node)
         {
-            Context.EmitWarning($"Syntax {node.Kind()} ({node.HumanReadableSummary()}) is not supported.\nGenerated code may not compile, or if it compiles, produce invalid results.", node);
+            LogWarning($"Syntax {node.Kind()} ({node.HumanReadableSummary()}) is not supported.", node);
             var lineSpan = node.GetLocation().GetLineSpan();
             AddCecilExpression($"/* Syntax '{node.Kind()}' is not supported in {lineSpan.Path} ({lineSpan.Span.Start.Line + 1},{lineSpan.Span.Start.Character + 1}):\n------\n{node}\n----*/");
         }
 
+        private void LogWarning(string message, SyntaxNode node)
+        {
+            Context.EmitWarning($"{message}\nGenerated code may not compile, or if it compiles, produce invalid results.", node);
+        }
+
         // Methods implementing explicit interfaces, static abstract methods from interfaces and overriden methods with covariant return types
         // needs to explicitly specify which methods they override.
         protected void AddToOverridenMethodsIfAppropriated(string methodVar, IMethodSymbol method)