From e7224f22575ec26ae89a6a9750303ef7d35c20ed Mon Sep 17 00:00:00 2001
From: Simon McKenzie <17579442+simonmckenzie@users.noreply.github.com>
Date: Wed, 14 Aug 2024 10:17:46 +1000
Subject: [PATCH] Handle generic types in method deduplication

This fixes an error where methods with the same parameters but different _generic type parameters_ were being treated as identical during deduplication, resulting in the loss of interface methods.

The fix is to use `genericsOptions: SymbolDisplayGenericsOptions.IncludeTypeParameters` when constucting the `SymbolDisplayFormat` used for deduplication.

Before:
`public void AMethod(Func<int> getValue) {}` produced a deduplication signature of `AMethod(Func)`
After:
`public void AMethod(Func<int> getValue) {}` produced a deduplication signature of `AMethod(Func<Int32>)`
---
 .../AutomaticInterface/Builder.cs             |  1 +
 AutomaticInterface/Tests/GeneratorTests.cs    | 49 +++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/AutomaticInterface/AutomaticInterface/Builder.cs b/AutomaticInterface/AutomaticInterface/Builder.cs
index b97e564..303c07a 100644
--- a/AutomaticInterface/AutomaticInterface/Builder.cs
+++ b/AutomaticInterface/AutomaticInterface/Builder.cs
@@ -13,6 +13,7 @@ public static class Builder
 
     private static readonly SymbolDisplayFormat MethodSignatureDisplayFormat =
         new(
+            genericsOptions: SymbolDisplayGenericsOptions.IncludeTypeParameters,
             memberOptions: SymbolDisplayMemberOptions.IncludeParameters,
             parameterOptions: SymbolDisplayParameterOptions.IncludeType
                 | SymbolDisplayParameterOptions.IncludeParamsRefOut
diff --git a/AutomaticInterface/Tests/GeneratorTests.cs b/AutomaticInterface/Tests/GeneratorTests.cs
index b548d97..ea312e2 100644
--- a/AutomaticInterface/Tests/GeneratorTests.cs
+++ b/AutomaticInterface/Tests/GeneratorTests.cs
@@ -2031,6 +2031,55 @@ public partial interface IDemoClass
         GenerateCode(code).Should().Be(expected);
     }
 
+    [Fact]
+    public void WorksWithGenericParameterOverloads()
+    {
+        const string code = """
+
+            using AutomaticInterface;
+
+            namespace AutomaticInterfaceExample;
+
+            [GenerateAutomaticInterface]
+            public class DemoClass
+            {
+                public void AMethod(Func<int> getValue) {}
+                
+                public void AMethod(Func<float> getValue) {}
+            }
+
+            """;
+
+        const string expected = """
+            //--------------------------------------------------------------------------------------------------
+            // <auto-generated>
+            //     This code was generated by a tool.
+            //
+            //     Changes to this file may cause incorrect behavior and will be lost if the code is regenerated.
+            // </auto-generated>
+            //--------------------------------------------------------------------------------------------------
+
+            using System.CodeDom.Compiler;
+            using AutomaticInterface;
+
+            namespace AutomaticInterfaceExample
+            {
+                [GeneratedCode("AutomaticInterface", "")]
+                public partial interface IDemoClass
+                {
+                    /// <inheritdoc />
+                    void AMethod(Func<int> getValue);
+                    
+                    /// <inheritdoc />
+                    void AMethod(Func<float> getValue);
+                    
+                }
+            }
+
+            """;
+        GenerateCode(code).Should().Be(expected);
+    }
+
     [Fact]
     public void WorksWithEventOverrides()
     {