From 78950443eac23a46e0d5a57ce6ac99bf95f722b1 Mon Sep 17 00:00:00 2001
From: Evan Haas <evan@lagerdata.com>
Date: Thu, 2 May 2024 23:41:16 -0700
Subject: [PATCH] Type: avoid overflow computing size of large _BitInt's

---
 src/aro/Type.zig     | 2 +-
 test/cases/_BitInt.c | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/aro/Type.zig b/src/aro/Type.zig
index 0ff08ee8..1ca932a8 100644
--- a/src/aro/Type.zig
+++ b/src/aro/Type.zig
@@ -1001,7 +1001,7 @@ pub fn sizeof(ty: Type, comp: *const Compilation) ?u64 {
         .double => comp.target.c_type_byte_size(.double),
         .float128 => 16,
         .bit_int => {
-            return std.mem.alignForward(u64, (ty.data.int.bits + 7) / 8, ty.alignof(comp));
+            return std.mem.alignForward(u64, (@as(u32, ty.data.int.bits) + 7) / 8, ty.alignof(comp));
         },
         // zig fmt: off
         .complex_char, .complex_schar, .complex_uchar, .complex_short, .complex_ushort, .complex_int,
diff --git a/test/cases/_BitInt.c b/test/cases/_BitInt.c
index 4f1e83d2..f815a73d 100644
--- a/test/cases/_BitInt.c
+++ b/test/cases/_BitInt.c
@@ -26,6 +26,7 @@ enum E: _BitInt(512) {
     A=6703903964971298549787012499102923063739682910296196688861780721860882015036773488400937149083451713845015929093243025426876941405973284973216824503042047WB,
     B,
 };
+_Static_assert(sizeof(_BitInt(65535)) == 8192, "");
 
 #define EXPECTED_ERRORS "_BitInt.c:3:1: warning: '_BitInt' in C17 and earlier is a Clang extension' [-Wbit-int-extension]" \
     "_BitInt.c:13:1: error: _BitInt of bit sizes greater than 65535 not supported" \