Merge pull request #19 from koenbeuk/issue-18

Don't rewrite cast expressions

src/EntityFrameworkCore.Projectables.Generator/ExpressionSyntaxRewriter.cs

@@ -136,11 +136,15 @@ namespace EntityFrameworkCore.Projectables.Generator
                     if (node.Parent is MemberAccessExpressionSyntax parentMemberAccessNode)
                     {
                         var targetSymbolInfo = _semanticModel.GetSymbolInfo(parentMemberAccessNode.Expression);
-                        if (targetSymbolInfo.Symbol is { Kind: SymbolKind.Parameter or SymbolKind.NamedType })
+                        if (targetSymbolInfo.Symbol is null)
                         {
                             rewrite = false;
                         }
-                        if (targetSymbolInfo.Symbol?.ContainingType is not null)
+                        else if (targetSymbolInfo.Symbol is { Kind: SymbolKind.Parameter or SymbolKind.NamedType })
+                        {
+                            rewrite = false;
+                        }
+                        else if (targetSymbolInfo.Symbol?.ContainingType is not null)
                         {
                             if (!_compilation.HasImplicitConversion(targetSymbolInfo.Symbol.ContainingType, _targetTypeSymbol) ||
                                 !SymbolEqualityComparer.Default.Equals(symbolInfo.Symbol.ContainingType, _targetTypeSymbol))

tests/EntityFrameworkCore.Projectables.Generator.Tests/ProjectionExpressionGeneratorTests.Cast.verified.txt

@@ -0,0 +1,15 @@
+using EntityFrameworkCore.Projectables;
+using Projectables.Repro;
+
+namespace EntityFrameworkCore.Projectables.Generated
+#nullable disable
+{
+    public static class Projectables_Repro_SomeExtensions_AsSomeResult
+    {
+        public static System.Linq.Expressions.Expression<System.Func<global::Projectables.Repro.SomeEntity, string>> Expression()
+        {
+            return (global::Projectables.Repro.SomeEntity e) => 
+                ((global::Projectables.Repro.SuperEntity)e).Superpower;
+        }
+    }
+}

tests/EntityFrameworkCore.Projectables.Generator.Tests/ProjectionExpressionGeneratorTests.EnumAccessor.received.txt

@@ -1,14 +0,0 @@
-using EntityFrameworkCore.Projectables;
-
-namespace EntityFrameworkCore.Projectables.Generated
-#nullable disable
-{
-    public static class _SomeExtensions_Test
-    {
-        public static System.Linq.Expressions.Expression<System.Func<global::SomeFlag, bool>> Expression()
-        {
-            return (global::SomeFlag f) => 
-                f == global::SomeFlag.Foo;
-        }
-    }
-}

tests/EntityFrameworkCore.Projectables.Generator.Tests/ProjectionExpressionGeneratorTests.cs

@@ -1045,6 +1045,39 @@ public static class SomeExtensions
             return Verifier.Verify(result.GeneratedTrees[0].ToString());
         }
 
+        [Fact]
+        public Task Cast()
+        {
+            var compilation = CreateCompilation(@"
+using EntityFrameworkCore.Projectables;
+
+namespace Projectables.Repro;
+
+public class SuperEntity : SomeEntity
+{
+    public string Superpower { get; set; }
+}
+
+public class SomeEntity
+{
+    public int Id { get; set; }
+}
+
+public static class SomeExtensions
+{
+    [Projectable]
+    public static string AsSomeResult(this SomeEntity e) => ((SuperEntity)e).Superpower;
+}
+");
+
+            var result = RunGenerator(compilation);
+
+            Assert.Empty(result.Diagnostics);
+            Assert.Single(result.GeneratedTrees);
+
+            return Verifier.Verify(result.GeneratedTrees[0].ToString());
+        }
+
         #region Helpers
 
         Compilation CreateCompilation(string source, bool expectedToCompile = true)