Merge pull request #312 from exyi/nullable-conversion-ignoreresult

Fix #310 - nullable conversion with ignored result

Author: dadhi

src/FastExpressionCompiler/FastExpressionCompiler.cs

@@ -2763,6 +2763,12 @@ private static bool TryEmitConvert(UnaryExpression expr, IReadOnlyList<PE> param
                 var underlyingNullableSourceType = Nullable.GetUnderlyingType(sourceType);
                 var targetType = expr.Type;
 
+                if (targetType.IsAssignableFrom(sourceType) && (parent & ParentFlags.IgnoreResult) != 0)
+                {
+                    // quick path for ignored result & conversion which can't cause exception: just do nothing
+                    return TryEmit(opExpr, paramExprs, il, ref closure, setup, parent);
+                }
+
                 if (sourceTypeIsNullable && targetType == underlyingNullableSourceType)
                 {
                     if (!TryEmit(opExpr, paramExprs, il, ref closure, setup, 
@@ -2813,9 +2819,7 @@ private static bool TryEmitConvert(UnaryExpression expr, IReadOnlyList<PE> param
                     if (method != null && method.DeclaringType == targetType && method.GetParameters()[0].ParameterType == sourceType)
                     {
                         il.Emit(OpCodes.Call, method);
-                        if ((parent & ParentFlags.IgnoreResult) != 0)
-                            il.Emit(OpCodes.Pop);
-                        return true;
+                        return il.EmitPopIfIgnoreResult(parent);
                     }
 
                     var actualSourceType = sourceTypeIsNullable ? underlyingNullableSourceType : sourceType;

test/FastExpressionCompiler.IssueTests/Issue310_InvalidProgramException_ignored_nullable.cs

@@ -0,0 +1,45 @@
+using NUnit.Framework;
+using System;
+using System.Linq.Expressions;
+#if LIGHT_EXPRESSION
+using static FastExpressionCompiler.LightExpression.Expression;
+namespace FastExpressionCompiler.LightExpression.IssueTests
+#else
+using static System.Linq.Expressions.Expression;
+namespace FastExpressionCompiler.IssueTests
+#endif
+{
+    [TestFixture]
+    public class Issue310_InvalidProgramException_ignored_nullable
+    {
+        public int Run()
+        {
+            Test1();
+            Test2();
+            return 2;
+        }
+
+        [Test]
+        public void Test1()
+        {
+            var p = Parameter(typeof(int), "tmp0");
+            var expr = 
+                Lambda<Action<int>>(Block(
+                Convert(p, typeof(int?)),
+                Default(typeof(void))), p);
+
+            var f = expr.CompileFast();
+            f(2);
+        }
+
+        [Test]
+        public void Test2()
+        {
+            var p = Parameter(typeof(int), "tmp0");
+            var expr = 
+                Lambda<Action<int>>(Convert(p, typeof(int?)), new[] { p });
+            var f = expr.CompileFast();
+            f(2);
+        }
+    }
+}

test/FastExpressionCompiler.TestsRunner.Net472/Program.cs

@@ -201,6 +201,9 @@ void Run(Func<int> run, string name = null)
                 Run(new Issue308_Wrong_delegate_type_returned_with_closure().Run);
                 Run(new FastExpressionCompiler.LightExpression.IssueTests.Issue308_Wrong_delegate_type_returned_with_closure().Run);
 
+                Run(new Issue310_InvalidProgramException_ignored_nullable().Run);
+                Run(new FastExpressionCompiler.LightExpression.IssueTests.Issue310_InvalidProgramException_ignored_nullable().Run);
+
                 Console.WriteLine($"============={Environment.NewLine}IssueTests are passing in {sw.ElapsedMilliseconds} ms.");
             });
 

test/FastExpressionCompiler.TestsRunner/Program.cs

@@ -226,6 +226,9 @@ void Run(Func<int> run, string name = null)
                 Run(new Issue308_Wrong_delegate_type_returned_with_closure().Run);
                 Run(new FastExpressionCompiler.LightExpression.IssueTests.Issue308_Wrong_delegate_type_returned_with_closure().Run);
 
+                Run(new Issue310_InvalidProgramException_ignored_nullable().Run);
+                Run(new FastExpressionCompiler.LightExpression.IssueTests.Issue310_InvalidProgramException_ignored_nullable().Run);
+
                 Console.WriteLine($"============={Environment.NewLine}IssueTests are passing in {sw.ElapsedMilliseconds} ms.");
             });