From dc1e5323abe427c1c1f52f5784b5d28a908c1f44 Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Fri, 27 Jun 2025 23:00:14 +0200
Subject: [PATCH] Segfault in the compiler when using a bitstruct constant
 defined using a cast with an operator #2248.

---
 releasenotes.md                               |  1 +
 src/compiler/sema_expr.c                      |  4 ++-
 .../bitstruct/bitstruct_no_inline_bit.c3t     | 29 +++++++++++++++++++
 3 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 test/test_suite/bitstruct/bitstruct_no_inline_bit.c3t

diff --git a/releasenotes.md b/releasenotes.md
index 9cb6d661c..b7fa8062c 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -68,6 +68,7 @@
 - Assert comparing untyped lists #2240.
 - Fix bugs relating to optional interface addr-of #2244.
 - Compiler null pointer when building a static-lib with -o somedir/... #2246
+- Segfault in the compiler when using a bitstruct constant defined using a cast with an operator #2248.
 
 ### Stdlib changes
 - Deprecate `String.is_zstr` and `String.quick_zstr` #2188.
diff --git a/src/compiler/sema_expr.c b/src/compiler/sema_expr.c
index 6557300e1..2084dbf8d 100644
--- a/src/compiler/sema_expr.c
+++ b/src/compiler/sema_expr.c
@@ -7515,6 +7515,8 @@ static bool sema_expr_analyse_bit(SemaContext *context, Expr *expr, Expr *left,
 		}
 		else if (is_bitstruct)
 		{
+			// Avoid merging with value casts, eg (Bitstruct)1
+			if (!expr_is_const_initializer(left) || !expr_is_const_initializer(right)) goto DONE;
 			ConstInitializer *merged = sema_merge_bitstruct_const_initializers(left->const_expr.initializer,
 																			   right->const_expr.initializer, op);
 			expr->const_expr.initializer = merged;
@@ -7537,7 +7539,7 @@ static bool sema_expr_analyse_bit(SemaContext *context, Expr *expr, Expr *left,
 			}
 		}
 	}
-
+DONE:
 	// 5. Assign the type
 	expr_binary_unify_failability(expr, left, right);
 	return true;
diff --git a/test/test_suite/bitstruct/bitstruct_no_inline_bit.c3t b/test/test_suite/bitstruct/bitstruct_no_inline_bit.c3t
new file mode 100644
index 000000000..50106b39f
--- /dev/null
+++ b/test/test_suite/bitstruct/bitstruct_no_inline_bit.c3t
@@ -0,0 +1,29 @@
+// #target: macos-x64
+module test;
+
+bitstruct BitstructFlags : uint
+{
+    bool first;
+    bool second;
+}
+const BitstructFlags B_FIRST = { true, false };
+const BitstructFlags B_FIRST2 = (BitstructFlags) 1;
+const BitstructFlags B_SECOND = { false, true };
+
+fn void main()
+{
+    BitstructFlags x = B_FIRST2 | B_SECOND;
+}
+
+/* #expect: test.ll
+
+@test.B_FIRST = local_unnamed_addr constant i32 1, align 4
+@test.B_FIRST2 = local_unnamed_addr constant i32 1, align 4
+@test.B_SECOND = local_unnamed_addr constant i32 2, align 4
+
+define void @test.main() #0 {
+entry:
+  %x = alloca i32, align 4
+  store i32 1, ptr %x, align 4
+  ret void
+}
\ No newline at end of file