Segfault in the compiler when using a bitstruct constant defined using a cast with an operator #2248.

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.

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;

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
+}