Merge pull request #75 from koenbeuk/issue-73

Don't throw when out of accessible expressions

src/EntityFrameworkCore.Projectables.Generator/ExpressionSyntaxRewriter.cs

@@ -72,6 +72,9 @@ namespace EntityFrameworkCore.Projectables.Generator
             {
                 var diagnostic = Diagnostic.Create(Diagnostics.NullConditionalRewriteUnsupported, node.GetLocation(), node);
                 _context.ReportDiagnostic(diagnostic);
+
+                // Return the original node, do not attempt further rewrites
+                return node;
             }
 
             else if (_nullConditionalRewriteSupport is NullConditionalRewriteSupport.Ignore)
@@ -112,34 +115,34 @@ namespace EntityFrameworkCore.Projectables.Generator
 
         public override SyntaxNode? VisitMemberBindingExpression(MemberBindingExpressionSyntax node)
         {
-            if (_conditionalAccessExpressionsStack.Count == 0)
+            if (_conditionalAccessExpressionsStack.Count > 0)
             {
-                throw new InvalidOperationException("Expected at least one conditional expression on the stack");
+                var targetExpression = _conditionalAccessExpressionsStack.Pop();
+
+                return _nullConditionalRewriteSupport switch {
+                    NullConditionalRewriteSupport.Ignore => SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, targetExpression, node.Name),
+                    NullConditionalRewriteSupport.Rewrite => SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, targetExpression, node.Name),
+                    _ => node
+                };
             }
 
-            var targetExpression = _conditionalAccessExpressionsStack.Pop();
+            return base.VisitMemberBindingExpression(node);
-
-            return _nullConditionalRewriteSupport switch {
-                NullConditionalRewriteSupport.Ignore => SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, targetExpression, node.Name),
-                NullConditionalRewriteSupport.Rewrite => SyntaxFactory.MemberAccessExpression(SyntaxKind.SimpleMemberAccessExpression, targetExpression, node.Name),
-                _ => node
-            };
         }
 
         public override SyntaxNode? VisitElementBindingExpression(ElementBindingExpressionSyntax node)
         {
-            if (_conditionalAccessExpressionsStack.Count == 0)
+            if (_conditionalAccessExpressionsStack.Count > 0)
             {
-                throw new InvalidOperationException("Expected at least one conditional expression on the stack");
+                var targetExpression = _conditionalAccessExpressionsStack.Pop();
+
+                return _nullConditionalRewriteSupport switch {
+                    NullConditionalRewriteSupport.Ignore => SyntaxFactory.ElementAccessExpression(targetExpression, node.ArgumentList),
+                    NullConditionalRewriteSupport.Rewrite => SyntaxFactory.ElementAccessExpression(targetExpression, node.ArgumentList),
+                    _ => Visit(node)
+                };
             }
 
-            var targetExpression = _conditionalAccessExpressionsStack.Pop();
+            return base.VisitElementBindingExpression(node);
-
-            return _nullConditionalRewriteSupport switch {
-                NullConditionalRewriteSupport.Ignore => SyntaxFactory.ElementAccessExpression(targetExpression, node.ArgumentList),
-                NullConditionalRewriteSupport.Rewrite => SyntaxFactory.ElementAccessExpression(targetExpression, node.ArgumentList),
-                _ => Visit(node)
-            };
         }
 
         public override SyntaxNode? VisitThisExpression(ThisExpressionSyntax node)

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

@@ -644,6 +644,69 @@ namespace Foo {
             Assert.Equal("EFP0002", diagnostic.Id);
         }
 
+        [Fact]
+        public void NullableMemberBinding_UndefinedSupport_IsBeingReported()
+        {
+            var compilation = CreateCompilation(@"
+using System;
+using System.Linq;
+using EntityFrameworkCore.Projectables;
+
+namespace Foo {
+    static class C {
+        [Projectable]
+        public static int? GetLength(this string input) => input?.Length;
+    }
+}
+");
+            var result = RunGenerator(compilation);
+
+            var diagnostic = Assert.Single(result.Diagnostics);
+            Assert.Equal("EFP0002", diagnostic.Id);
+        }
+
+
+        [Fact]
+        public void MultiLevelNullableMemberBinding_UndefinedSupport_IsBeingReported()
+        {
+            var compilation = CreateCompilation(@"
+using System;
+using System.Linq;
+using EntityFrameworkCore.Projectables;
+
+namespace Foo {
+        public record Address
+        {
+            public int Id { get; set; }
+            public string? Country { get; set; }
+        }
+
+        public record Party
+        {
+            public int Id { get; set; }
+
+            public Address? Address { get; set; }
+        }
+
+        public record Entity
+        {
+            public int Id { get; set; }
+
+            public Party? Left { get; set; }
+            public Party? Right { get; set; }
+
+            [Projectable]
+            public bool IsSameCountry => Left?.Address?.Country == Right?.Address?.Country;
+        }
+}
+");
+            var result = RunGenerator(compilation);
+
+            Assert.All(result.Diagnostics, diagnostic => {
+                Assert.Equal("EFP0002", diagnostic.Id);
+            });
+        }
+
         [Fact]
         public Task NullableMemberBinding_WithIgnoreSupport_IsBeingRewritten()
         {