From efeb9e627e256d0c7966836c0b3a0247cfd34c27 Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Fri, 11 Oct 2024 13:26:22 +0200
Subject: [PATCH] Interfaces not correctly copied with generics #1545.

---
 releasenotes.md                               |  1 +
 src/compiler/copying.c                        |  1 +
 test/test_suite/generic/generic_idents.c3t    |  1 +
 test/test_suite/generic/generic_interface.c3t | 31 +++++++++++++++++++
 4 files changed, 34 insertions(+)
 create mode 100644 test/test_suite/generic/generic_interface.c3t

diff --git a/releasenotes.md b/releasenotes.md
index 4721edd1c..55eead461 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -29,6 +29,7 @@
 - Improved error message on invalid subscript index type #1535.
 - Improved error message when declaring a variable `void!`.
 - Cannot use void as a generic parameter #1546
+- Interfaces not correctly copied with generics #1545
 
 ### Stdlib changes
 - Remove unintended print of `char[]` as String
diff --git a/src/compiler/copying.c b/src/compiler/copying.c
index 3df845e07..ea4165c19 100644
--- a/src/compiler/copying.c
+++ b/src/compiler/copying.c
@@ -941,6 +941,7 @@ Decl *copy_decl(CopyStruct *c, Decl *decl)
 		case DECL_ERASED:
 			break;
 		case DECL_INTERFACE:
+			copy_decl_type(copy);
 			MACRO_COPY_TYPE_LIST(copy->interfaces);
 			MACRO_COPY_DECL_LIST(copy->methods);
 			MACRO_COPY_DECL_LIST(copy->interface_methods);
diff --git a/test/test_suite/generic/generic_idents.c3t b/test/test_suite/generic/generic_idents.c3t
index eebc5a6bb..c6c20e595 100644
--- a/test/test_suite/generic/generic_idents.c3t
+++ b/test/test_suite/generic/generic_idents.c3t
@@ -1,3 +1,4 @@
+// #target: macos-aarch64
 module gen(<Type>);
 
 fn Type mult(Type x)
diff --git a/test/test_suite/generic/generic_interface.c3t b/test/test_suite/generic/generic_interface.c3t
new file mode 100644
index 000000000..6a9b2ef6f
--- /dev/null
+++ b/test/test_suite/generic/generic_interface.c3t
@@ -0,0 +1,31 @@
+// #target: macos-aarch64
+module base;
+
+module test(<MyType>);
+import base;
+interface Zzz
+{
+    fn void zzz(MyType t);
+}
+struct TestStruct (Zzz)
+{
+	String data;
+}
+fn void TestStruct.zzz(&self, MyType t) @dynamic { }
+
+module app;
+import test;
+fn int main()
+{
+	TestStruct(<int>) ts;
+	return 0;
+}
+
+/* #expect: app.ll
+
+define i32 @main() #0 {
+entry:
+  %ts = alloca %TestStruct, align 8
+  call void @llvm.memset.p0.i64(ptr align 8 %ts, i8 0, i64 16, i1 false)
+  ret i32 0
+}