From b4b14674b479ee45e0b8fea5963b3965dab518e4 Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Mon, 6 Oct 2025 20:50:56 +0200
Subject: [PATCH] - Bitstruct truncated constant error escapes `$defined` #2515

---
 releasenotes.md                                  | 1 +
 src/compiler/sema_expr.c                         | 5 +++--
 src/compiler/sema_initializers.c                 | 4 ++--
 src/compiler/sema_internal.h                     | 2 +-
 test/test_suite/bitstruct/bitrstruct_defined.c3t | 6 ++++++
 5 files changed, 13 insertions(+), 5 deletions(-)
 create mode 100644 test/test_suite/bitstruct/bitrstruct_defined.c3t

diff --git a/releasenotes.md b/releasenotes.md
index d2a9e7254..d47a0fcfb 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -9,6 +9,7 @@
 - Bug in `io::write_using_write_byte`.
 - Bitstruct value cannot be used to index a const array in compile time. #2512
 - Compiler fails to stop error print in recursive macro, and also prints unnecessary "inline at" #2513.
+- Bitstruct truncated constant error escapes `$defined` #2515
 
 ### Stdlib changes
 
diff --git a/src/compiler/sema_expr.c b/src/compiler/sema_expr.c
index 6e36092a8..2b0d5f68e 100644
--- a/src/compiler/sema_expr.c
+++ b/src/compiler/sema_expr.c
@@ -6905,7 +6905,7 @@ static bool sema_expr_analyse_assign(SemaContext *context, Expr *expr, Expr *lef
 	}
 	if (left->expr_kind == EXPR_BITACCESS)
 	{
-		if (!sema_bit_assignment_check(context, right, left->access_resolved_expr.ref)) return false;
+		if (!sema_bit_assignment_check(context, right, left->access_resolved_expr.ref, failed_ref)) return false;
 		expr->expr_kind = EXPR_BITASSIGN;
 	}
 	return true;
@@ -12310,7 +12310,7 @@ static inline bool sema_insert_binary_overload(SemaContext *context, Expr *expr,
 }
 
 // Check if the assignment fits
-bool sema_bit_assignment_check(SemaContext *context, Expr *right, Decl *member)
+bool sema_bit_assignment_check(SemaContext *context, Expr *right, Decl *member, bool *failed_ref)
 {
 	// Don't check non-consts and non integers.
 	if (!sema_cast_const(right) || !type_is_integer(right->type)) return true;
@@ -12322,6 +12322,7 @@ bool sema_bit_assignment_check(SemaContext *context, Expr *right, Decl *member)
 
 	if (int_bits_needed(right->const_expr.ixx) > bits)
 	{
+		if (failed_ref) return *failed_ref = true, false;
 		RETURN_SEMA_ERROR(right, "This constant would be truncated if stored in the "
 								 "bitstruct, do you need a wider bit range?");
 	}
diff --git a/src/compiler/sema_initializers.c b/src/compiler/sema_initializers.c
index b32ef58f5..cc9137af1 100644
--- a/src/compiler/sema_initializers.c
+++ b/src/compiler/sema_initializers.c
@@ -277,7 +277,7 @@ static inline bool sema_expr_analyse_struct_plain_initializer(SemaContext *conte
 		if (!sema_analyse_expr_rhs(context, members[i]->type, element, true, no_match_ref, false)) return false;
 		if (member->decl_kind == DECL_VAR && member->var.kind == VARDECL_BITMEMBER)
 		{
-			if (!sema_bit_assignment_check(context, element, members[i])) return false;
+			if (!sema_bit_assignment_check(context, element, members[i], no_match_ref)) return false;
 		}
 		optional = optional || IS_OPTIONAL(element);
 	}
@@ -529,7 +529,7 @@ static bool sema_expr_analyse_designated_initializer(SemaContext *context, Type
 		if (!sema_analyse_expr_rhs(context, result, value, true, no_match_ref, false)) return false;
 		if (is_bitmember)
 		{
-			if (!sema_bit_assignment_check(context, value, member)) return false;
+			if (!sema_bit_assignment_check(context, value, member, no_match_ref)) return false;
 		}
 		optional = optional || IS_OPTIONAL(value);
 		expr->resolve_status = RESOLVE_DONE;
diff --git a/src/compiler/sema_internal.h b/src/compiler/sema_internal.h
index 80f1cf9f6..740f3d249 100644
--- a/src/compiler/sema_internal.h
+++ b/src/compiler/sema_internal.h
@@ -113,7 +113,7 @@ Expr *sema_resolve_string_ident(SemaContext *context, Expr *inner, bool report_m
 bool sema_analyse_asm(SemaContext *context, AsmInlineBlock *block, Ast *asm_stmt);
 bool sema_expr_analyse_sprintf(SemaContext *context, Expr *expr, Expr *format_string, Expr **args, unsigned num_args);
 
-bool sema_bit_assignment_check(SemaContext *context, Expr *right, Decl *member);
+bool sema_bit_assignment_check(SemaContext *context, Expr *right, Decl *member, bool *failed_ref);
 CondResult sema_check_comp_time_bool(SemaContext *context, Expr *expr);
 
 bool sema_expr_check_assign(SemaContext *context, Expr *expr, bool *failed_ref);
diff --git a/test/test_suite/bitstruct/bitrstruct_defined.c3t b/test/test_suite/bitstruct/bitrstruct_defined.c3t
new file mode 100644
index 000000000..a9ab2e5b8
--- /dev/null
+++ b/test/test_suite/bitstruct/bitrstruct_defined.c3t
@@ -0,0 +1,6 @@
+bitstruct Test : char
+{
+	char type : 0..2;
+}
+
+$assert !$defined((Test){123});
\ No newline at end of file