Support generic constraints on methods

InterfaceStubGenerator.Core/InterfaceStubGenerator.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using System.Text;
 
@@ -197,7 +198,7 @@ namespace {ns}
     [global::System.Reflection.Obfuscation(Exclude=true)]
     [global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
     partial class AutoGenerated{classDeclaration}
-        : {interfaceSymbol.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat)}{GenerateConstraints(interfaceSymbol)}
+        : {interfaceSymbol.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat)}{GenerateConstraints(interfaceSymbol.TypeParameters, false)}
 
     {{
         /// <inheritdoc />
@@ -312,43 +313,49 @@ void ProcessDisposableMethod(StringBuilder source, IMethodSymbol methodSymbol)
             WriteMethodClosing(source);
         }
 
-        string GenerateConstraints(INamedTypeSymbol iface)
+        string GenerateConstraints(ImmutableArray<ITypeParameterSymbol> typeParameters, bool isOverrideOrExplicitImplementation)
         {
             var source = new StringBuilder();
             // Need to loop over the constraints and create them
-            foreach(var typeParameter in iface.TypeParameters)
+            foreach(var typeParameter in typeParameters)
             {
-                WriteConstraitsForTypeParameter(source, typeParameter);
+                WriteConstraitsForTypeParameter(source, typeParameter, isOverrideOrExplicitImplementation);
             }
 
             return source.ToString();
         }
 
-        void WriteConstraitsForTypeParameter(StringBuilder source, ITypeParameterSymbol typeParameter)
+        void WriteConstraitsForTypeParameter(StringBuilder source, ITypeParameterSymbol typeParameter, bool isOverrideOrExplicitImplementation)
         {
+            // Explicit interface implementations and ovverrides can only have class or struct constraints
+
             var parameters = new List<string>();
             if(typeParameter.HasReferenceTypeConstraint)
             {
                 parameters.Add("class");
             }
-            if (typeParameter.HasUnmanagedTypeConstraint)
+            if (typeParameter.HasUnmanagedTypeConstraint && !isOverrideOrExplicitImplementation)
             {
                 parameters.Add("unmanaged");
             }
             if (typeParameter.HasValueTypeConstraint)
             {
                 parameters.Add("struct");
             }
-            if (typeParameter.HasNotNullConstraint)
+            if (typeParameter.HasNotNullConstraint && !isOverrideOrExplicitImplementation)
             {
                 parameters.Add("notnull");
             }
-            foreach(var typeConstraint in typeParameter.ConstraintTypes)
+            if (!isOverrideOrExplicitImplementation)
             {
-                parameters.Add(typeConstraint.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat));
+                foreach (var typeConstraint in typeParameter.ConstraintTypes)
+                {
+                    parameters.Add(typeConstraint.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat));
+                }
             }
+
             // new constraint has to be last
-            if (typeParameter.HasConstructorConstraint)
+            if (typeParameter.HasConstructorConstraint && !isOverrideOrExplicitImplementation)
             {
                 parameters.Add("new()");
             }
@@ -398,8 +405,8 @@ void WriteMethodOpening(StringBuilder source, IMethodSymbol methodSymbol)
                 source.Append(string.Join(", ", list));
             }
 
-           source.Append(@")
-        {");
+           source.Append(@$") {GenerateConstraints(methodSymbol.TypeParameters, true)}
+        {{");
         }
 
         void WriteMethodClosing(StringBuilder source) => source.Append(@"        }");

Refit.Tests/InheritedGenericInterfacesApi.cs

@@ -33,7 +33,11 @@ public interface IDataCrudApi<T, TKey> where T : class
         Task<T> Create([Body] T payload);
 
         [Get("")]
-        Task<List<T>> ReadAll();
+        Task<List<T>> ReadAll<TFoo>() where TFoo : new();
+
+        [Get("")]
+        Task<List<T>> ReadAll<TFoo, TBar>() where TFoo : new()
+                                            where TBar : struct;
 
         [Get("/{key}")]
         Task<T> ReadOne(TKey key);

Refit.Tests/InterfaceStubGenerator.cs

@@ -33,6 +33,11 @@ public void GenerateInterfaceStubsSmokeTest()
                 IntegrationTestHelper.GetPath("InheritedInterfacesApi.cs"),
                 IntegrationTestHelper.GetPath("InheritedGenericInterfacesApi.cs"));
 
+            var diags = inputCompilation.GetDiagnostics();
+
+            // Make sure we don't have any errors
+            Assert.Empty(diags.Where(d => d.Severity == DiagnosticSeverity.Error));
+
             var rundriver = driver.RunGeneratorsAndUpdateCompilation(inputCompilation, out var outputCompiliation, out var diagnostics);
 
             var runResult = rundriver.GetRunResult();
@@ -47,9 +52,24 @@ public void GenerateInterfaceStubsSmokeTest()
 
         static Compilation CreateCompilation(params string[] sourceFiles)
         {
+            var keyReferences = new[]
+            {
+                typeof(Binder),
+                typeof(GetAttribute),
+                typeof(RichardSzalay.MockHttp.MockHttpMessageHandler),
+                typeof(System.Reactive.Unit),
+                typeof(System.Linq.Enumerable),
+                typeof(Newtonsoft.Json.JsonConvert),
+                typeof(Xunit.FactAttribute),
+                typeof(System.Net.Http.HttpContent),
+                typeof(ModelObject),
+                typeof(Attribute)
+            };
+
+
             return CSharpCompilation.Create("compilation",
                 sourceFiles.Select(source => CSharpSyntaxTree.ParseText(File.ReadAllText(source))),
-                new[] { MetadataReference.CreateFromFile(typeof(GetAttribute).GetTypeInfo().Assembly.Location) },
+                                   keyReferences.Select(t => MetadataReference.CreateFromFile(t.Assembly.Location)),
                 new CSharpCompilationOptions(OutputKind.ConsoleApplication));
 
         }