From 8ed390c394afc6b75567108b87aa3f5fe5c81d9c Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Sat, 16 Nov 2024 23:08:54 +0100
Subject: [PATCH] A distinct inline pointer type can now participate in pointer
 arithmetics.

---
 releasenotes.md                          |  1 +
 src/compiler/compiler_internal.h         | 17 ++++++++++++++++-
 src/compiler/llvm_codegen_type.c         |  2 +-
 test/test_suite/distinct/distinct_add.c3 |  7 +++++++
 4 files changed, 25 insertions(+), 2 deletions(-)
 create mode 100644 test/test_suite/distinct/distinct_add.c3

diff --git a/releasenotes.md b/releasenotes.md
index df037f8d4..50252e404 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -10,6 +10,7 @@
 - Fix bug where `a > 0 ? f() : g()` could cause a compiler crash if both returned `void!`.
 - `@builtin` was not respected for generic modules #1617.
 - Fix issue writing a single byte in the WriteBuffer
+- A distinct inline pointer type can now participate in pointer arithmetics.
 
 ### Stdlib changes
 - Add `io::MultiReader`, `io::MultiWriter`, and `io::TeeReader` structs.
diff --git a/src/compiler/compiler_internal.h b/src/compiler/compiler_internal.h
index 0312ac665..ecd263f27 100644
--- a/src/compiler/compiler_internal.h
+++ b/src/compiler/compiler_internal.h
@@ -2698,10 +2698,25 @@ INLINE CanonicalType *type_pointer_type(Type *type)
 	return res->pointer;
 }
 
+static inline Type *type_flat_distinct_inline(Type *type);
+
 INLINE bool type_is_pointer_like(Type *type)
 {
 	TypeKind kind = type->type_kind;
-	return kind == TYPE_POINTER || (kind == TYPE_VECTOR && type->array.base->canonical->type_kind == TYPE_POINTER);
+	if (kind == TYPE_DISTINCT)
+	{
+		type = type_flat_distinct_inline(type);
+		kind = type->type_kind;
+	}
+	switch (kind)
+	{
+		case TYPE_POINTER:
+			return true;
+		case TYPE_VECTOR:
+			return type_is_pointer_like(type->array.base->canonical);
+		default:
+			return false;
+	}
 }
 
 INLINE bool type_is_pointer_vector(Type *type)
diff --git a/src/compiler/llvm_codegen_type.c b/src/compiler/llvm_codegen_type.c
index 24ca77994..0e5d064d8 100644
--- a/src/compiler/llvm_codegen_type.c
+++ b/src/compiler/llvm_codegen_type.c
@@ -276,7 +276,7 @@ LLVMTypeRef llvm_func_type(GenContext *context, FunctionPrototype *prototype)
 
 LLVMTypeRef llvm_get_pointee_type(GenContext *c, Type *any_type)
 {
-	any_type = any_type->canonical;
+	any_type = type_lowering(any_type);
 	ASSERT0(any_type->type_kind == TYPE_POINTER);
 	if (any_type == type_voidptr) return llvm_get_type(c, type_char);
 	return llvm_get_type(c, any_type->pointer);
diff --git a/test/test_suite/distinct/distinct_add.c3 b/test/test_suite/distinct/distinct_add.c3
new file mode 100644
index 000000000..2481e9e50
--- /dev/null
+++ b/test/test_suite/distinct/distinct_add.c3
@@ -0,0 +1,7 @@
+import std;
+fn void main()
+{
+	ZString a = "abc";
+	ZString b = a + 1;
+	io::printfn("%s", b);
+}