Switch SwiftSelf<T> position requirement to last (#108547)

This is added as the last parameter by the Swift compiler, so to support
instance calls taking parameters this needs to come last.

Author: jakobbotsch

src/coreclr/jit/importercalls.cpp

@@ -2226,9 +2226,9 @@ void Compiler::impPopArgsForSwiftCall(GenTreeCall* call, CORINFO_SIG_INFO* sig,
                     BADCODE("Duplicate SwiftSelf parameter");
                 }
 
-                if (argIndex != 0)
+                if (argIndex != (sig->numArgs - 1))
                 {
-                    BADCODE("SwiftSelf<T> must be the first argument in the signature");
+                    BADCODE("SwiftSelf<T> must be the last argument in the signature");
                 }
 
                 selfType                = info.compCompHnd->getTypeInstantiationArgument(argClass, 0);

src/mono/mono/metadata/marshal.c

@@ -3714,9 +3714,9 @@ mono_marshal_get_native_wrapper (MonoMethod *method, gboolean check_exceptions,
 						break;
 					} else if (param_klass == swift_error || param_klass == swift_error_ptr) {
 						swift_error_args++;
-					} else if (param_gklass && (param_gklass->container_class == swift_self_t) && i > 0) {
+					} else if (param_gklass && (param_gklass->container_class == swift_self_t) && (i != method->signature->param_count - 1)) {
 						swift_error_args = swift_self_args = 0;
-						mono_error_set_generic_error (emitted_error, "System", "InvalidProgramException", "SwiftSelf<T> must be the first argument in the signature.");
+						mono_error_set_generic_error (emitted_error, "System", "InvalidProgramException", "SwiftSelf<T> must be the last argument in the signature.");
 						break;
 					} else if (param_gklass && (param_gklass->container_class == swift_self_t) && m_type_is_byref (method->signature->params [i])) {
 						swift_error_args = swift_self_args = 0;

src/tests/Interop/Swift/SwiftSelfContext/SwiftSelfContext.cs

@@ -61,11 +61,11 @@ public struct FrozenNonEnregisteredStruct
     }
 
     [UnmanagedCallConv(CallConvs = new Type[] { typeof(CallConvSwift) })]
-    [DllImport(SwiftLib, EntryPoint = "$s16SwiftSelfContext24FrozenEnregisteredStructV3Sums5Int64VyF")]
+    [DllImport(SwiftLib, EntryPoint = "$s16SwiftSelfContext24FrozenEnregisteredStructV3sums5Int64VyF")]
     public static extern long SumFrozenEnregisteredStruct(SwiftSelf<FrozenEnregisteredStruct> self);
 
     [UnmanagedCallConv(CallConvs = new Type[] { typeof(CallConvSwift) })]
-    [DllImport(SwiftLib, EntryPoint = "$s16SwiftSelfContext27FrozenNonEnregisteredStructV3Sums5Int64VyF")]
+    [DllImport(SwiftLib, EntryPoint = "$s16SwiftSelfContext27FrozenNonEnregisteredStructV3sums5Int64VyF")]
     public static extern long SumFrozenNonEnregisteredStruct(SwiftSelf<FrozenNonEnregisteredStruct> self);
 
     [Fact]
@@ -81,4 +81,27 @@ public unsafe static void TestSelfIsFrozenNonEnregisteredStruct()
         long sum = SumFrozenNonEnregisteredStruct(new SwiftSelf<FrozenNonEnregisteredStruct>(new FrozenNonEnregisteredStruct { A = 10, B = 20, C = 30, D = 40, E = 50 }));
         Assert.Equal(150, sum);
     }
+
+    [UnmanagedCallConv(CallConvs = new Type[] { typeof(CallConvSwift) })]
+    [DllImport(SwiftLib, EntryPoint = "$s16SwiftSelfContext24FrozenEnregisteredStructV16sumWithExtraArgs1c1dS2f_SftF")]
+    public static extern float SumFrozenEnregisteredStructWithExtraArgs(float c, float d, SwiftSelf<FrozenEnregisteredStruct> self);
+
+    [UnmanagedCallConv(CallConvs = new Type[] { typeof(CallConvSwift) })]
+    [DllImport(SwiftLib, EntryPoint = "$s16SwiftSelfContext27FrozenNonEnregisteredStructV16sumWithExtraArgs1f1gS2f_SftF")]
+    public static extern float SumFrozenNonEnregisteredStructWithExtraArgs(float f, float g, SwiftSelf<FrozenNonEnregisteredStruct> self);
+
+    [Fact]
+    public unsafe static void TestSelfIsFrozenEnregisteredStructWithExtraArgs()
+    {
+        float sum = SumFrozenEnregisteredStructWithExtraArgs(3f, 4f, new SwiftSelf<FrozenEnregisteredStruct>(new FrozenEnregisteredStruct { A = 10, B = 20 }));
+        Assert.Equal(37f, sum);
+    }
+
+    [Fact]
+    [SkipOnMono("https://github.com/dotnet/runtime/issues/108855")]
+    public unsafe static void TestSelfIsFrozenNonEnregisteredStructWithExtraArgs()
+    {
+        float sum = SumFrozenNonEnregisteredStructWithExtraArgs(3f, 4f, new SwiftSelf<FrozenNonEnregisteredStruct>(new FrozenNonEnregisteredStruct { A = 10, B = 20, C = 30, D = 40, E = 50 }));
+        Assert.Equal(157f, sum);
+    }
 }

src/tests/Interop/Swift/SwiftSelfContext/SwiftSelfContext.swift

@@ -26,9 +26,13 @@ public struct FrozenEnregisteredStruct
     let a : Int64;
     let b : Int64;
 
-    public func Sum() -> Int64 {
+    public func sum() -> Int64 {
         return a + b
     }
+
+    public func sumWithExtraArgs(c: Float, d: Float) -> Float {
+        return Float(a + b) + c + d
+    }
 }
 
 @frozen
@@ -39,7 +43,11 @@ public struct FrozenNonEnregisteredStruct {
     let d : Int64;
     let e : Int64;
 
-    public func Sum() -> Int64 {
+    public func sum() -> Int64 {
         return a + b + c + d + e
     }
-}
+
+    public func sumWithExtraArgs(f: Float, g: Float) -> Float {
+        return Float(a + b + c + d + e) + f + g
+    }
+}