From c87509e07fd355b8930b2d92f6ca83ea4275c707 Mon Sep 17 00:00:00 2001
From: Koen Bekkenutte <2912652+kbekkenutte@users.noreply.github.com>
Date: Mon, 31 May 2021 02:05:57 +0800
Subject: [PATCH] Raise diagnostics when not exposing expression bodies members

---
 .../AnalyzerReleases.Shipped.md               |  3 ++
 .../AnalyzerReleases.Unshipped.md             |  5 +++
 .../Diagnostics.cs                            | 21 +++++++++
 .../ProjectableInterpreter.cs                 | 14 ++++++
 .../ProjectionExpressionGeneratorTests.cs     | 43 +++++++++++++++++++
 5 files changed, 86 insertions(+)
 create mode 100644 src/EntityFrameworkCore.Projections.Generator/AnalyzerReleases.Shipped.md
 create mode 100644 src/EntityFrameworkCore.Projections.Generator/AnalyzerReleases.Unshipped.md
 create mode 100644 src/EntityFrameworkCore.Projections.Generator/Diagnostics.cs

diff --git a/src/EntityFrameworkCore.Projections.Generator/AnalyzerReleases.Shipped.md b/src/EntityFrameworkCore.Projections.Generator/AnalyzerReleases.Shipped.md
new file mode 100644
index 0000000..d567f14
--- /dev/null
+++ b/src/EntityFrameworkCore.Projections.Generator/AnalyzerReleases.Shipped.md
@@ -0,0 +1,3 @@
+; Shipped analyzer releases
+; https://github.com/dotnet/roslyn-analyzers/blob/master/src/Microsoft.CodeAnalysis.Analyzers/ReleaseTrackingAnalyzers.Help.md
+
diff --git a/src/EntityFrameworkCore.Projections.Generator/AnalyzerReleases.Unshipped.md b/src/EntityFrameworkCore.Projections.Generator/AnalyzerReleases.Unshipped.md
new file mode 100644
index 0000000..f69adf0
--- /dev/null
+++ b/src/EntityFrameworkCore.Projections.Generator/AnalyzerReleases.Unshipped.md
@@ -0,0 +1,5 @@
+### New Rules
+
+Rule ID | Category | Severity | Notes
+--------|----------|----------|--------------------
+EFP0001 |  Design  |  Error   | ST0001_AnalyzerName
diff --git a/src/EntityFrameworkCore.Projections.Generator/Diagnostics.cs b/src/EntityFrameworkCore.Projections.Generator/Diagnostics.cs
new file mode 100644
index 0000000..36f833e
--- /dev/null
+++ b/src/EntityFrameworkCore.Projections.Generator/Diagnostics.cs
@@ -0,0 +1,21 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis;
+
+namespace EntityFrameworkCore.Projections.Generator
+{
+    public static class Diagnostics
+    {
+        public static readonly DiagnosticDescriptor RequiresExpressionBodyDefinition = new(
+            id: "EFP0001",
+            title: "Method or property should expose an expression body definition",
+            messageFormat: "Method or property '{0}' should expose an expression body definition.",
+            category: "Design",
+            DiagnosticSeverity.Error,
+            isEnabledByDefault: true);
+
+    }
+}
diff --git a/src/EntityFrameworkCore.Projections.Generator/ProjectableInterpreter.cs b/src/EntityFrameworkCore.Projections.Generator/ProjectableInterpreter.cs
index 4a34bb6..211bb40 100644
--- a/src/EntityFrameworkCore.Projections.Generator/ProjectableInterpreter.cs
+++ b/src/EntityFrameworkCore.Projections.Generator/ProjectableInterpreter.cs
@@ -84,6 +84,13 @@ namespace EntityFrameworkCore.Projections.Generator
 
             if (memberDeclarationSyntax is MethodDeclarationSyntax methodDeclarationSyntax)
             {
+                if (methodDeclarationSyntax.ExpressionBody is null)
+                {
+                    var diagnostic = Diagnostic.Create(Diagnostics.RequiresExpressionBodyDefinition, methodDeclarationSyntax.GetLocation(), memberSymbol.Name);
+                    context.ReportDiagnostic(diagnostic);
+                    return null;
+                }
+
                 descriptor.ReturnTypeName = methodDeclarationSyntax.ReturnType.ToString();
                 descriptor.Body = expressionSyntaxRewriter.Visit(methodDeclarationSyntax.ExpressionBody.Expression);
                 foreach (var additionalParameter in ((ParameterListSyntax)parameterSyntaxRewriter.Visit(methodDeclarationSyntax.ParameterList)).Parameters)
@@ -93,6 +100,13 @@ namespace EntityFrameworkCore.Projections.Generator
             }
             else if (memberDeclarationSyntax is PropertyDeclarationSyntax propertyDeclarationSyntax)
             {
+                if (propertyDeclarationSyntax.ExpressionBody is null)
+                {
+                    var diagnostic = Diagnostic.Create(Diagnostics.RequiresExpressionBodyDefinition, propertyDeclarationSyntax.GetLocation(), memberSymbol.Name);
+                    context.ReportDiagnostic(diagnostic);
+                    return null;
+                }
+
                 descriptor.ReturnTypeName = propertyDeclarationSyntax.Type.ToString();
                 descriptor.Body = expressionSyntaxRewriter.Visit(propertyDeclarationSyntax.ExpressionBody.Expression);
             }
diff --git a/tests/EntityFrameworkCore.Projections.Generator.Tests/ProjectionExpressionGeneratorTests.cs b/tests/EntityFrameworkCore.Projections.Generator.Tests/ProjectionExpressionGeneratorTests.cs
index cc746fe..3ead468 100644
--- a/tests/EntityFrameworkCore.Projections.Generator.Tests/ProjectionExpressionGeneratorTests.cs
+++ b/tests/EntityFrameworkCore.Projections.Generator.Tests/ProjectionExpressionGeneratorTests.cs
@@ -340,6 +340,49 @@ namespace Foo {
             return Verifier.Verify(result.GeneratedTrees[0].ToString());
         }
 
+        [Fact]
+        public void BlockBodiedMember_RaisesDiagnostics()
+        {
+            var compilation = CreateCompilation(@"
+using System;
+using EntityFrameworkCore.Projections;
+namespace Foo {
+    class C {
+        [Projectable]
+        public int Foo 
+        {
+            get => 1;
+        }
+    }
+}
+");
+
+            var result = RunGenerator(compilation);
+
+            Assert.Single(result.Diagnostics);
+        }
+
+        [Fact]
+        public void BlockBodiedMethod_RaisesDiagnostics()
+        {
+            var compilation = CreateCompilation(@"
+using System;
+using EntityFrameworkCore.Projections;
+namespace Foo {
+    class C {
+        [Projectable]
+        public int Foo() 
+        {
+            return 1;
+        }
+    }
+}
+");
+
+            var result = RunGenerator(compilation);
+
+            Assert.Single(result.Diagnostics);
+        }
 
         #region Helpers