From ac50730dfdb4fea6c6bfb6e09f10fd0733fa3995 Mon Sep 17 00:00:00 2001
From: Stanislav Silin <silin.stanislav@outlook.com>
Date: Sat, 4 Feb 2023 17:07:22 +0200
Subject: [PATCH] Fix source generation for type duplicates.

---
 .../DapperJsonSourceGenerator.cs              | 76 ++++++++++---------
 ...ypeMappingDuplicatesAsHandled.verified.txt |  3 +
 src/Dapper.Json.Tests/MainTest.cs             | 16 +++-
 3 files changed, 60 insertions(+), 35 deletions(-)
 create mode 100644 src/Dapper.Json.Tests/MainTest.TypeMappingDuplicatesAsHandled.verified.txt

diff --git a/src/Dapper.Json.SourceGenerator/DapperJsonSourceGenerator.cs b/src/Dapper.Json.SourceGenerator/DapperJsonSourceGenerator.cs
index 1c5738d..bda4ff5 100644
--- a/src/Dapper.Json.SourceGenerator/DapperJsonSourceGenerator.cs
+++ b/src/Dapper.Json.SourceGenerator/DapperJsonSourceGenerator.cs
@@ -1,4 +1,4 @@
-using System;
+using System.Collections.Immutable;
 using System.Linq;
 using System.Threading;
 using DuckInterface;
@@ -18,45 +18,33 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
         var jsons = context.SyntaxProvider
             .CreateSyntaxProvider(SelectJsonT, Transform);
 
-        var combined = jsons.Combine(jsonType);
-        context.RegisterImplementationSourceOutput(combined, Generate);
-    }
+        var combined = jsons.Collect()
+            .Combine(jsonType);
 
-    private ITypeSymbol Transform(GeneratorSyntaxContext context, CancellationToken cancellationToken)
-    {
-        switch (context.Node)
-        {
-            case GenericNameSyntax:
-                return context.SemanticModel.GetTypeInfo(context.Node, cancellationToken).Type;
-            case MemberAccessExpressionSyntax memberAccess:
-                var symbolInfo = context.SemanticModel.GetSymbolInfo(memberAccess.Name, cancellationToken);
-                if (symbolInfo.Symbol is IMethodSymbol methodSymbol)
-                {
-                    return methodSymbol.ReturnType;
-                }
-                return null;
-            default:
-                return null;
-        }
+        context.RegisterImplementationSourceOutput(combined, Generate);
     }
 
-    private void Generate(SourceProductionContext context, (ITypeSymbol Target, INamedTypeSymbol JsonType) input)
+    private void Generate(SourceProductionContext context,
+        (ImmutableArray<ITypeSymbol> Targets, INamedTypeSymbol JsonType) input)
     {
-        var (target, jsonType) = input;
-        if (target is not INamedTypeSymbol namedTypeSymbol ||
-            !SymbolEqualityComparer.Default.Equals(namedTypeSymbol.ConstructedFrom, jsonType))
+        var (targets, jsonType) = input;
+        var uniqueTargets = targets.Distinct(SymbolEqualityComparer.Default);
+        foreach (var target in uniqueTargets)
         {
-            return;
-        }
+            if (target is not INamedTypeSymbol namedTypeSymbol ||
+                !SymbolEqualityComparer.Default.Equals(namedTypeSymbol.ConstructedFrom, jsonType))
+            {
+                return;
+            }
 
-        var type = namedTypeSymbol.TypeArguments.First();
-        if (type is ITypeParameterSymbol)
-        {
-            return;
-        }
+            var type = namedTypeSymbol.TypeArguments.First();
+            if (type is ITypeParameterSymbol)
+            {
+                return;
+            }
 
-        var safeTypeName = type.ToSafeGlobalName();
-        var source = @$"using System;
+            var safeTypeName = type.ToSafeGlobalName();
+            var source = @$"using System;
 
 namespace Dapper.Json
 {{
@@ -70,7 +58,27 @@ public static void Init()
     }}
 }}
 ";
-        context.AddSource($"Dapper.Json.{safeTypeName}.g.cs", source.ToSourceText());
+            context.AddSource($"Dapper.Json.{safeTypeName}.g.cs", source.ToSourceText());
+        }
+    }
+
+    private ITypeSymbol Transform(GeneratorSyntaxContext context, CancellationToken cancellationToken)
+    {
+        switch (context.Node)
+        {
+            case GenericNameSyntax:
+                return context.SemanticModel.GetTypeInfo(context.Node, cancellationToken).Type;
+            case MemberAccessExpressionSyntax memberAccess:
+                var symbolInfo = context.SemanticModel.GetSymbolInfo(memberAccess.Name, cancellationToken);
+                if (symbolInfo.Symbol is IMethodSymbol methodSymbol)
+                {
+                    return methodSymbol.ReturnType;
+                }
+
+                return null;
+            default:
+                return null;
+        }
     }
 
     private bool SelectJsonT(SyntaxNode syntaxNode, CancellationToken token)
diff --git a/src/Dapper.Json.Tests/MainTest.TypeMappingDuplicatesAsHandled.verified.txt b/src/Dapper.Json.Tests/MainTest.TypeMappingDuplicatesAsHandled.verified.txt
new file mode 100644
index 0000000..ca8baff
--- /dev/null
+++ b/src/Dapper.Json.Tests/MainTest.TypeMappingDuplicatesAsHandled.verified.txt
@@ -0,0 +1,3 @@
+[
+  Role
+]
\ No newline at end of file
diff --git a/src/Dapper.Json.Tests/MainTest.cs b/src/Dapper.Json.Tests/MainTest.cs
index ff1184e..66f381d 100644
--- a/src/Dapper.Json.Tests/MainTest.cs
+++ b/src/Dapper.Json.Tests/MainTest.cs
@@ -66,7 +66,7 @@ public async Task TypeMappingForGenericsAreIgnored()
 
         await Verify(handlers);
     }
-    
+
     [Fact]
     public async Task TypeMappingWithAsJsonExtensionIsDetected()
     {
@@ -80,6 +80,20 @@ public async Task TypeMappingWithAsJsonExtensionIsDetected()
         await Verify(handlers);
     }
 
+    [Fact]
+    public async Task TypeMappingDuplicatesAsHandled()
+    {
+        var newProject = await TestProject.Project.ReplacePartsOfDocumentAsync(
+            "Program.cs",
+            ("// place to replace 0", "public class Role { public string Name { get; set;} }"),
+            ("public Json<string[]> Emails { get; set; }", "public Json<Role> Role { get; set; }"),
+            ("// place to replace 1", "var role = new Role().AsJson();"));
+
+        var handlers = await Execute(newProject);
+
+        await Verify(handlers);
+    }
+
     private static async Task<string[]> Execute(Project project)
     {
         var assembly = await project.CompileToRealAssembly();