Add support for notnull, struct, class and new() generic constraints

src/EntityFrameworkCore.Projectables.Generator/ProjectableInterpreter.cs

@@ -137,26 +137,48 @@ x is IPropertySymbol xProperty &&
                     descriptor.ClassTypeParameterList = descriptor.ClassTypeParameterList.AddParameters(
                         SyntaxFactory.TypeParameter(additionalClassTypeParameter.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat))
                     );
-
+
+                    // See https://github.com/dotnet/roslyn/blob/d7e010bbe5b1d37837417fc5e79ecb2fd9b7b487/src/VisualStudio/CSharp/Impl/ObjectBrowser/DescriptionBuilder.cs#L340
                     if (!additionalClassTypeParameter.ConstraintTypes.IsDefaultOrEmpty)
                     {
                         descriptor.ClassConstraintClauses ??= SyntaxFactory.List<TypeParameterConstraintClauseSyntax>();
 
+                        var parameters = new List<TypeConstraintSyntax>();
+
+                        if (additionalClassTypeParameter.HasReferenceTypeConstraint)
+                        {
+                            parameters.Add(MakeTypeConstraint("class"));
+                        }
+
+                        if (additionalClassTypeParameter.HasValueTypeConstraint)
+                        {
+                            parameters.Add(MakeTypeConstraint("struct"));
+                        }
+
+                        if (additionalClassTypeParameter.HasNotNullConstraint)
+                        {
+                            parameters.Add(MakeTypeConstraint("notnull"));
+                        }
+
+                        parameters.AddRange(additionalClassTypeParameter
+                            .ConstraintTypes
+                            .Select(c => 
+                                MakeTypeConstraint(c.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat))
+                            )
+                        );
+
+                        if (additionalClassTypeParameter.HasConstructorConstraint)
+                        {
+                            parameters.Add(MakeTypeConstraint("new()"));
+                        }
+
                         descriptor.ClassConstraintClauses = descriptor.ClassConstraintClauses.Value.Add(
                             SyntaxFactory.TypeParameterConstraintClause(
                                 SyntaxFactory.IdentifierName(additionalClassTypeParameter.Name),
-                                SyntaxFactory.SeparatedList<TypeParameterConstraintSyntax>(
-                                    additionalClassTypeParameter
-                                        .ConstraintTypes
-                                        .Select(c => SyntaxFactory.TypeConstraint(
-                                            SyntaxFactory.IdentifierName(c.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat))
-                                        ))
-                                )
+                                SyntaxFactory.SeparatedList<TypeParameterConstraintSyntax>(parameters)
                             )
                         );
                     }
-
-                    // todo: add additional type constraints
                 }
             }
 
@@ -245,5 +267,7 @@ x is IPropertySymbol xProperty &&
 
             return descriptor;
         }
+
+        private static TypeConstraintSyntax MakeTypeConstraint(string constraint) => SyntaxFactory.TypeConstraint(SyntaxFactory.IdentifierName(constraint));
     }
 }

src/EntityFrameworkCore.Projectables/Services/ProjectableExpressionReplacer.cs

@@ -111,4 +111,4 @@ PropertyInfo property when nodeExpression is not null
             return base.VisitMember(node);
         }
     }
-}
+}

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

@@ -0,0 +1,20 @@
+// <auto-generated/>
+#nullable disable
+using System;
+using System.Linq;
+using System.Collections.Generic;
+using EntityFrameworkCore.Projectables;
+using Foo;
+
+namespace EntityFrameworkCore.Projectables.Generated
+{
+    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
+    static class Foo_Entity_FullName<T, TEnum>
+        where T : global::Foo.TypedObject<TEnum> where TEnum : struct, global::System.Enum
+    {
+        static global::System.Linq.Expressions.Expression<global::System.Func<global::Foo.Entity<T, TEnum>, string>> Expression()
+        {
+            return (global::Foo.Entity<T, TEnum> @this) => $"{@this.FirstName} {@this.LastName} {@this.SomeSubobject.SomeProp}";
+        }
+    }
+}

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

@@ -0,0 +1,19 @@
+// <auto-generated/>
+#nullable disable
+using System;
+using System.Linq;
+using System.Collections.Generic;
+using EntityFrameworkCore.Projectables;
+using Foo;
+
+namespace EntityFrameworkCore.Projectables.Generated
+{
+    [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
+    static class Foo_Entity_FullName<T>
+    {
+        static global::System.Linq.Expressions.Expression<global::System.Func<global::Foo.Entity<T>, string>> Expression()
+        {
+            return (global::Foo.Entity<T> @this) => $"{@this.FirstName} {@this.LastName} {@this.SomeSubobject}";
+        }
+    }
+}

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

@@ -7,7 +7,7 @@ namespace EntityFrameworkCore.Projectables.Generated
 {
     [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
     static class _EntityBase_GetId<TId>
-        where TId : global::System.ICloneable
+        where TId : global::System.ICloneable, new()
     {
         static global::System.Linq.Expressions.Expression<global::System.Func<TId>> Expression()
         {

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

@@ -921,6 +921,72 @@ public static string EnforceString<T>(T value) where T : unmanaged
             return Verifier.Verify(result.GeneratedTrees[0].ToString());
         }
 
+        [Fact]
+        public Task GenericClassesWithContraints_AreRewritten()
+        {
+            var compilation = CreateCompilation(@"
+using System;
+using System.Linq;
+using System.Collections.Generic;
+using EntityFrameworkCore.Projectables;
+
+namespace Foo {
+    public class TypedObject<TEnum> where TEnum : struct, System.Enum
+    {
+        public TEnum SomeProp { get; set; }
+    }
+
+    public abstract class Entity<T, TEnum>where T : TypedObject<TEnum> where TEnum : struct, System.Enum 
+    {
+        public int Id { get; set; }
+        public string FirstName { get; set; }
+        public string LastName { get; set; }
+        public T SomeSubobject { get; set; }
+
+        [Projectable]
+        public string FullName => $""{FirstName} {LastName} {SomeSubobject.SomeProp}"";
+    }
+}
+");
+            var result = RunGenerator(compilation);
+
+            Assert.Empty(result.Diagnostics);
+            Assert.Single(result.GeneratedTrees);
+
+            return Verifier.Verify(result.GeneratedTrees[0].ToString());
+        }
+
+        [Fact]
+        public Task GenericClassesWithTypeContraints_AreRewritten()
+        {
+            var compilation = CreateCompilation(@"
+using System;
+using System.Linq;
+using System.Collections.Generic;
+using EntityFrameworkCore.Projectables;
+
+namespace Foo {
+    public abstract class Entity<T> where T : notnull
+    {
+        public int Id { get; set; }
+        public string FirstName { get; set; }
+        public string LastName { get; set; }
+        public T SomeSubobject { get; set; }
+
+        [Projectable]
+        public string FullName => $""{FirstName} {LastName} {SomeSubobject}"";
+    }
+}
+");
+
+            var result = RunGenerator(compilation);
+
+            Assert.Empty(result.Diagnostics);
+            // Assert.Single(result.GeneratedTrees);
+
+            return Verifier.Verify(result.GeneratedTrees[0].ToString());
+        }
+
         [Fact]
         public Task DeclarationTypeNamesAreGettingFullyQualified()
         {