Improved expression tree generation

src/EntityFrameworkCore.Projectables.Generator/ExpressionSyntaxRewriter.cs

@@ -49,17 +49,34 @@ namespace EntityFrameworkCore.Projectables.Generator
         {
             var symbolInfo = _semanticModel.GetSymbolInfo(node);
 
-            if (symbolInfo.Symbol is not null && symbolInfo.Symbol.Kind is SymbolKind.Property or SymbolKind.Method or SymbolKind.Field && SymbolEqualityComparer.Default.Equals(symbolInfo.Symbol.ContainingType, _targetTypeSymbol))
+            if (symbolInfo.Symbol is not null)
             {
-                return SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
-                    SyntaxFactory.IdentifierName("@this"),
-                    node
-                );
-            }
-            else
-            {
-                return base.VisitIdentifierName(node);
+                if (symbolInfo.Symbol.Kind is SymbolKind.Property or SymbolKind.Method or SymbolKind.Field && SymbolEqualityComparer.Default.Equals(symbolInfo.Symbol.ContainingType, _targetTypeSymbol))
+                {
+                    return SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression,
+                        SyntaxFactory.IdentifierName("@this"),
+                        node
+                    );
+                }
+                else if (symbolInfo.Symbol.Kind is SymbolKind.NamedType)
+                {
+                    var typeInfo = _semanticModel.GetTypeInfo(node);
+
+                    if (typeInfo.Type is not null)
+                    {
+                        return SyntaxFactory.ParseTypeName(
+                            typeInfo.Type.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat)
+                        );
+                    }
+                }
             }
+         
+            return base.VisitIdentifierName(node);
+        }
+
+        public override SyntaxNode? VisitQualifiedName(QualifiedNameSyntax node)
+        {
+            return base.VisitQualifiedName(node);
         }
     }
 }

src/EntityFrameworkCore.Projectables.Generator/ProjectableInterpreter.cs

@@ -92,7 +92,13 @@ namespace EntityFrameworkCore.Projectables.Generator
                     return null;
                 }
 
-                descriptor.ReturnTypeName = returnTypeSyntaxRewriter.Visit(methodDeclarationSyntax.ReturnType).ToString();
+                var returnTypeSymbol = semanticModel.GetSymbolInfo(returnTypeSyntaxRewriter.Visit(methodDeclarationSyntax.ReturnType)).Symbol;
+                if (returnTypeSymbol is null)
+                {
+                    return null;
+                }
+
+                descriptor.ReturnTypeName = returnTypeSymbol.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat);
                 descriptor.Body = expressionSyntaxRewriter.Visit(methodDeclarationSyntax.ExpressionBody.Expression);
                 foreach (var additionalParameter in ((ParameterListSyntax)parameterSyntaxRewriter.Visit(methodDeclarationSyntax.ParameterList)).Parameters)
                 {
@@ -108,7 +114,13 @@ namespace EntityFrameworkCore.Projectables.Generator
                     return null;
                 }
 
-                descriptor.ReturnTypeName = propertyDeclarationSyntax.Type.ToString();
+                var returnTypeSymbol = semanticModel.GetSymbolInfo(returnTypeSyntaxRewriter.Visit(propertyDeclarationSyntax.Type)).Symbol;
+                if (returnTypeSymbol is null)
+                {
+                    return null;
+                }
+
+                descriptor.ReturnTypeName = returnTypeSymbol.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat);
                 descriptor.Body = expressionSyntaxRewriter.Visit(propertyDeclarationSyntax.ExpressionBody.Expression);
             }
             else

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

@@ -8,7 +8,7 @@ namespace EntityFrameworkCore.Projectables.Generated
 {
     public static class Foo_C_Foo
     {
-        public static System.Linq.Expressions.Expression<System.Func<global::Foo.C, D>> Expression => 
+        public static System.Linq.Expressions.Expression<System.Func<global::Foo.C, global::Foo.D>> Expression => 
             (global::Foo.C @this) => @this.Dees.First();
     }
 }

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

@@ -0,0 +1,14 @@
+using System;
+using System.Linq;
+using EntityFrameworkCore.Projectables;
+using Foo;
+
+namespace EntityFrameworkCore.Projectables.Generated
+#nullable disable
+{
+    public static class Foo_C_Foo
+    {
+        public static System.Linq.Expressions.Expression<System.Func<global::Foo.C, int>> Expression => 
+            (global::Foo.C @this) => @this.Dees.OfType<global::Foo.D>().Count();
+    }
+}

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

@@ -292,6 +292,33 @@ namespace Foo {
             return Verifier.Verify(result.GeneratedTrees[0].ToString());
         }
 
+        [Fact]
+        public Task TypesInBodyGetsFullyQualified()
+        {
+            var compilation = CreateCompilation(@"
+using System;
+using System.Linq;
+using EntityFrameworkCore.Projectables;
+namespace Foo {
+    class D { }
+    
+    class C {
+        public System.Collections.Generic.List<D> Dees { get; set; }
+
+        [Projectable]
+        public int Foo => Dees.OfType<D>().Count();
+    }
+}
+");
+
+            var result = RunGenerator(compilation);
+
+            Assert.Empty(result.Diagnostics);
+            Assert.Single(result.GeneratedTrees);
+
+            return Verifier.Verify(result.GeneratedTrees[0].ToString());
+        }
+
         [Fact]
         public Task ProjectableExtensionMethod()
         {