fixed the #307

Author: dadhi

src/FastExpressionCompiler/FastExpressionCompiler.cs

@@ -4357,19 +4357,20 @@ private static bool TryEmitSwitch(SwitchExpression expr, IReadOnlyList<PE> param
                 //- if switch SwitchValue is a nullable parameter, we should call getValue only once and store the result.
                 //- use comparison methods (when defined)
 
-                var cases = expr.Cases;
                 var endLabel = il.DefineLabel();
+                var cases = expr.Cases;
                 var labels = new Label[cases.Count];
-                for (var index = 0; index < cases.Count; index++)
+                var dontIgnoreTestResult = parent & ~ParentFlags.IgnoreResult;
+                for (var caseIndex = 0; caseIndex < cases.Count; ++caseIndex)
                 {
-                    var switchCase = cases[index];
-                    labels[index] = il.DefineLabel();
+                    var cs = cases[caseIndex];
+                    labels[caseIndex] = il.DefineLabel();
 
-                    foreach (var switchCaseTestValue in switchCase.TestValues)
+                    foreach (var caseTestValue in cs.TestValues)
                     {
-                        if (!TryEmitComparison(expr.SwitchValue, switchCaseTestValue, ExpressionType.Equal, paramExprs, il, ref closure, setup, parent))
+                        if (!TryEmitComparison(expr.SwitchValue, caseTestValue, ExpressionType.Equal, paramExprs, il, ref closure, setup, dontIgnoreTestResult))
                             return false;
-                        il.Emit(OpCodes.Brtrue, labels[index]);
+                        il.Emit(OpCodes.Brtrue, labels[caseIndex]);
                     }
                 }
 
@@ -4380,19 +4381,18 @@ private static bool TryEmitSwitch(SwitchExpression expr, IReadOnlyList<PE> param
                     il.Emit(OpCodes.Br, endLabel);
                 }
 
-                for (var index = 0; index < cases.Count; ++index)
+                for (var caseIndex = 0; caseIndex < cases.Count; ++caseIndex)
                 {
-                    var switchCase = cases[index];
-                    il.MarkLabel(labels[index]);
-                    if (!TryEmit(switchCase.Body, paramExprs, il, ref closure, setup, parent))
+                    il.MarkLabel(labels[caseIndex]);
+                    var cs = cases[caseIndex];
+                    if (!TryEmit(cs.Body, paramExprs, il, ref closure, setup, parent))
                         return false;
 
-                    if (index != cases.Count - 1)
+                    if (caseIndex != cases.Count - 1)
                         il.Emit(OpCodes.Br, endLabel);
                 }
 
                 il.MarkLabel(endLabel);
-
                 return true;
             }
 
@@ -4414,8 +4414,8 @@ private static bool TryEmitComparison(Expression exprLeft, Expression exprRight,
                 }
 
                 int lVarIndex = -1, rVarIndex = -1;
-                if (!TryEmit(exprLeft, paramExprs, il, ref closure, setup, 
-                    parent & ~ParentFlags.IgnoreResult & ~ParentFlags.InstanceAccess))
+                var operandParent = parent & ~ParentFlags.IgnoreResult & ~ParentFlags.InstanceAccess;
+                if (!TryEmit(exprLeft, paramExprs, il, ref closure, setup, operandParent))
                     return false;
 
                 if (leftIsNullable)
@@ -4425,8 +4425,7 @@ private static bool TryEmitComparison(Expression exprLeft, Expression exprRight,
                     leftOpType = Nullable.GetUnderlyingType(leftOpType);
                 }
 
-                if (!TryEmit(exprRight, paramExprs, il, ref closure, setup, 
-                    parent & ~ParentFlags.IgnoreResult & ~ParentFlags.InstanceAccess))
+                if (!TryEmit(exprRight, paramExprs, il, ref closure, setup, operandParent))
                     return false;
 
                 if (leftOpType != rightOpType)

test/FastExpressionCompiler.IssueTests/Issue307_Switch_with_fall_through_throws_InvalidProgramException.cs

@@ -19,7 +19,7 @@ public int Run()
             return 1;
         }
 
-        // [Test]
+        [Test]
         public void Test1()
         {
             var param = Parameter(typeof(int), "p");
@@ -39,6 +39,18 @@ public void Test1()
                 param);
 
             lambda.PrintCSharp();
+            // (Func<int, string>)((int p) => //$
+            // {
+            //     switch (p)
+            //     {
+            //         case (int)1:
+            //         case (int)2:
+            //             return "foo";
+            //         default:
+            //             return "bar";
+            //     }
+            //     string__58225482:;
+            // });
 
             var compiled = lambda.CompileSys();
             compiled.PrintIL();

test/FastExpressionCompiler.TestsRunner.Net472/Program.cs

@@ -195,6 +195,9 @@ void Run(Func<int> run, string name = null)
                 Run(new Issue305_CompileFast_generates_incorrect_code_with_arrays_and_printing().Run);
                 Run(new FastExpressionCompiler.LightExpression.IssueTests.Issue305_CompileFast_generates_incorrect_code_with_arrays_and_printing().Run);
 
+                Run(new Issue307_Switch_with_fall_through_throws_InvalidProgramException().Run);
+                Run(new FastExpressionCompiler.LightExpression.IssueTests.Issue307_Switch_with_fall_through_throws_InvalidProgramException().Run);
+
                 Console.WriteLine($"============={Environment.NewLine}IssueTests are passing in {sw.ElapsedMilliseconds} ms.");
             });
 

test/FastExpressionCompiler.TestsRunner/Program.cs

@@ -11,6 +11,7 @@ public static void Main()
         {
             RunAllTests();
 
+            // new FastExpressionCompiler.LightExpression.IssueTests.Issue307_Switch_with_fall_through_throws_InvalidProgramException().Run();
             // new FastExpressionCompiler.LightExpression.IssueTests.Issue305_CompileFast_generates_incorrect_code_with_arrays_and_printing().Run();
             // new FastExpressionCompiler.LightExpression.IssueTests.Issue261_Loop_wih_conditions_fails().Run();
             // new FastExpressionCompiler.LightExpression.IssueTests.Issue222_Make_AutoMapper_FEC_branch_to_pass_all_the_tests().Run();
@@ -216,6 +217,8 @@ void Run(Func<int> run, string name = null)
 
                 Run(new Issue305_CompileFast_generates_incorrect_code_with_arrays_and_printing().Run);
                 Run(new FastExpressionCompiler.LightExpression.IssueTests.Issue305_CompileFast_generates_incorrect_code_with_arrays_and_printing().Run);
+                Run(new Issue307_Switch_with_fall_through_throws_InvalidProgramException().Run);
+                Run(new FastExpressionCompiler.LightExpression.IssueTests.Issue307_Switch_with_fall_through_throws_InvalidProgramException().Run);
 
                 Console.WriteLine($"============={Environment.NewLine}IssueTests are passing in {sw.ElapsedMilliseconds} ms.");
             });