From 3ce15bd7afbfcfe67cef3c8b0a615215d7d38753 Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Sun, 15 Jun 2025 22:35:44 +0200
Subject: [PATCH] Incorrect codegen if a macro ends with unreachable and is
 assigned to something. #2210

---
 releasenotes.md                               |  1 +
 src/compiler/llvm_codegen_expr.c              |  4 +-
 .../assert/unreachable_in_assign.c3t          | 37 +++++++++++++++++++
 3 files changed, 41 insertions(+), 1 deletion(-)
 create mode 100644 test/test_suite/assert/unreachable_in_assign.c3t

diff --git a/releasenotes.md b/releasenotes.md
index 967337a03..ce7d82c8d 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -40,6 +40,7 @@
 - Fix to `is_array_or_slice_of_char` #2214.
 - Method on array slice caused segfault #2211.
 - In some cases, the compiler would dereference a compile time null. #2215
+- Incorrect codegen if a macro ends with unreachable and is assigned to something. #2210
 
 ### Stdlib changes
 - Deprecate `String.is_zstr` and `String.quick_zstr` #2188.
diff --git a/src/compiler/llvm_codegen_expr.c b/src/compiler/llvm_codegen_expr.c
index 694ade6cb..983a0ed2b 100644
--- a/src/compiler/llvm_codegen_expr.c
+++ b/src/compiler/llvm_codegen_expr.c
@@ -122,6 +122,7 @@ BEValue llvm_emit_assign_expr(GenContext *c, BEValue *ref, Expr *expr, LLVMValue
 		BEValue result;
 		// Emit the fault type.
 		llvm_emit_expr(c, &result, expr->inner_expr);
+
 		llvm_value_rvalue(c, &result);
 
 		LLVMValueRef err_val = result.value;
@@ -201,7 +202,7 @@ BEValue llvm_emit_assign_expr(GenContext *c, BEValue *ref, Expr *expr, LLVMValue
 		{
 			llvm_emit_expr(c, &value, expr);
 		}
-
+		if (!c->current_block) goto AFTER_STORE;
 		if (value.type != type_void) llvm_store(c, ref, &value);
 	}
 
@@ -209,6 +210,7 @@ BEValue llvm_emit_assign_expr(GenContext *c, BEValue *ref, Expr *expr, LLVMValue
 	{
 		llvm_store_to_ptr_raw(c, optional, llvm_get_zero(c, type_fault), type_fault);
 	}
+AFTER_STORE:;
 	POP_CATCH();
 
 	if (assign_block)
diff --git a/test/test_suite/assert/unreachable_in_assign.c3t b/test/test_suite/assert/unreachable_in_assign.c3t
new file mode 100644
index 000000000..937a6d766
--- /dev/null
+++ b/test/test_suite/assert/unreachable_in_assign.c3t
@@ -0,0 +1,37 @@
+// #target: windows-x64
+module test;
+
+macro int create_int2() {
+	$$unreachable();
+}
+
+fn void test()
+{
+	int x = create_int2();
+}
+macro int? create_int()
+{
+	$$unreachable();
+}
+
+fn int main()
+{
+	int? x = create_int();
+}
+
+/* #expect: test.ll
+
+define void @test.test() #0 {
+entry:
+  %x = alloca i32, align 4
+  %blockret = alloca i32, align 4
+  unreachable
+}
+
+define i32 @main() #0 {
+entry:
+  %x = alloca i32, align 4
+  %x.f = alloca i64, align 8
+  %blockret = alloca i32, align 4
+  unreachable
+}
\ No newline at end of file