[libc-commits] [libc] Libc/gcc bug (PR #95600)

[via libc-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libc

Author: Schrodinger ZHU Yifan (SchrodingerZhu)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/95600.diff


2 Files Affected:

- (modified) libc/src/__support/macros/attributes.h (+1-1) 
- (modified) libc/src/__support/threads/linux/rwlock.h (+3-2) 


``````````diff
diff --git a/libc/src/__support/macros/attributes.h b/libc/src/__support/macros/attributes.h
index 7e8e2ddfac9b1..c6474673de85a 100644
--- a/libc/src/__support/macros/attributes.h
+++ b/libc/src/__support/macros/attributes.h
@@ -42,7 +42,7 @@
 #define LIBC_CONSTINIT
 #endif
 
-#ifdef __clang__
+#if defined(__clang__) && __has_attribute(preferred_type)
 #define LIBC_PREFERED_TYPE(TYPE) [[clang::preferred_type(TYPE)]]
 #else
 #define LIBC_PREFERED_TYPE(TYPE)
diff --git a/libc/src/__support/threads/linux/rwlock.h b/libc/src/__support/threads/linux/rwlock.h
index 5db0590fd6aa0..1778995cf3766 100644
--- a/libc/src/__support/threads/linux/rwlock.h
+++ b/libc/src/__support/threads/linux/rwlock.h
@@ -370,8 +370,9 @@ class RwLock {
 public:
   LIBC_INLINE constexpr RwLock(Role preference = Role::Reader,
                                bool is_pshared = false)
-      : is_pshared(is_pshared), preference(static_cast<unsigned>(preference)),
-        state(0), writer_tid(0), queue() {}
+      : is_pshared(is_pshared),
+        preference(static_cast<unsigned>(preference) & 1u), state(0),
+        writer_tid(0), queue() {}
 
   [[nodiscard]]
   LIBC_INLINE LockResult try_read_lock() {

``````````

</details>


https://github.com/llvm/llvm-project/pull/95600