Revert "[libc] add basic lifetime annotations for support data structures" #164012

SchrodingerZhu · 2025-10-17T20:34:53Z

Reverts #145933 due to broken aarch64 buildbots.

…ures (#1…" This reverts commit c0e0a33.

SchrodingerZhu · 2025-10-17T20:35:09Z

Merge this as it is a build fix

llvmbot · 2025-10-17T20:35:27Z

@llvm/pr-subscribers-libc

Author: Schrodinger ZHU Yifan (SchrodingerZhu)

Changes

Reverts llvm/llvm-project#145933 due to broken aarch64 buildbots.

Full diff: https://github.com/llvm/llvm-project/pull/164012.diff

12 Files Affected:

(modified) libc/src/__support/CPP/algorithm.h (+2-6)
(modified) libc/src/__support/CPP/array.h (+6-13)
(modified) libc/src/__support/CPP/atomic.h (+1-1)
(modified) libc/src/__support/CPP/mutex.h (+3-7)
(modified) libc/src/__support/CPP/optional.h (+4-8)
(modified) libc/src/__support/CPP/span.h (+3-4)
(modified) libc/src/__support/CPP/string.h (+6-13)
(modified) libc/src/__support/CPP/string_view.h (+1-14)
(modified) libc/src/__support/CPP/stringstream.h (+1-3)
(modified) libc/src/__support/CPP/utility/forward.h (+2-4)
(modified) libc/src/__support/CPP/utility/move.h (+1-2)
(modified) libc/src/__support/macros/attributes.h (-80)

diff --git a/libc/src/__support/CPP/algorithm.h b/libc/src/__support/CPP/algorithm.h
index 1acd1581a942e..de0c47369d945 100644
--- a/libc/src/__support/CPP/algorithm.h
+++ b/libc/src/__support/CPP/algorithm.h
@@ -24,15 +24,11 @@ template <class T = void> struct bit_and {};
 template <class T = void> struct bit_or {};
 template <class T = void> struct bit_xor {};
 
-template <class T>
-LIBC_INLINE constexpr const T &max(LIBC_LIFETIME_BOUND const T &a,
-                                   LIBC_LIFETIME_BOUND const T &b) {
+template <class T> LIBC_INLINE constexpr const T &max(const T &a, const T &b) {
   return (a < b) ? b : a;
 }
 
-template <class T>
-LIBC_INLINE constexpr const T &min(LIBC_LIFETIME_BOUND const T &a,
-                                   LIBC_LIFETIME_BOUND const T &b) {
+template <class T> LIBC_INLINE constexpr const T &min(const T &a, const T &b) {
   return (a < b) ? a : b;
 }
 
diff --git a/libc/src/__support/CPP/array.h b/libc/src/__support/CPP/array.h
index 44c493fd2d50b..db0a986b71205 100644
--- a/libc/src/__support/CPP/array.h
+++ b/libc/src/__support/CPP/array.h
@@ -31,22 +31,15 @@ template <class T, size_t N> struct array {
   LIBC_INLINE constexpr T *data() { return Data; }
   LIBC_INLINE constexpr const T *data() const { return Data; }
 
-  LIBC_INLINE constexpr T &front() LIBC_LIFETIME_BOUND { return Data[0]; }
-  LIBC_INLINE constexpr const T &front() const LIBC_LIFETIME_BOUND {
-    return Data[0];
-  }
+  LIBC_INLINE constexpr T &front() { return Data[0]; }
+  LIBC_INLINE constexpr const T &front() const { return Data[0]; }
 
-  LIBC_INLINE constexpr T &back() LIBC_LIFETIME_BOUND { return Data[N - 1]; }
-  LIBC_INLINE constexpr const T &back() const LIBC_LIFETIME_BOUND {
-    return Data[N - 1];
-  }
+  LIBC_INLINE constexpr T &back() { return Data[N - 1]; }
+  LIBC_INLINE constexpr const T &back() const { return Data[N - 1]; }
 
-  LIBC_INLINE constexpr T &operator[](size_t Index) LIBC_LIFETIME_BOUND {
-    return Data[Index];
-  }
+  LIBC_INLINE constexpr T &operator[](size_t Index) { return Data[Index]; }
 
-  LIBC_INLINE constexpr const T &
-  operator[](size_t Index) const LIBC_LIFETIME_BOUND {
+  LIBC_INLINE constexpr const T &operator[](size_t Index) const {
     return Data[Index];
   }
 
diff --git a/libc/src/__support/CPP/atomic.h b/libc/src/__support/CPP/atomic.h
index ac60f5e9cda09..53b583c04ba15 100644
--- a/libc/src/__support/CPP/atomic.h
+++ b/libc/src/__support/CPP/atomic.h
@@ -256,7 +256,7 @@ template <typename T> struct Atomic {
   LIBC_INLINE void set(T rhs) { val = rhs; }
 };
 
-template <typename T> struct LIBC_GSL_POINTER AtomicRef {
+template <typename T> struct AtomicRef {
   static_assert(is_trivially_copyable_v<T> && is_copy_constructible_v<T> &&
                     is_move_constructible_v<T> && is_copy_assignable_v<T> &&
                     is_move_assignable_v<T>,
diff --git a/libc/src/__support/CPP/mutex.h b/libc/src/__support/CPP/mutex.h
index 2ad33da34a80d..8a3102426e2d6 100644
--- a/libc/src/__support/CPP/mutex.h
+++ b/libc/src/__support/CPP/mutex.h
@@ -9,7 +9,6 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_CPP_MUTEX_H
 #define LLVM_LIBC_SRC___SUPPORT_CPP_MUTEX_H
 
-#include "src/__support/macros/attributes.h"
 #include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE_DECL {
@@ -29,17 +28,14 @@ template <typename MutexType> class lock_guard {
 
 public:
   // Calls `m.lock()` upon resource acquisition.
-  LIBC_INLINE explicit lock_guard(LIBC_LIFETIME_BOUND MutexType &m) : mutex(m) {
-    mutex.lock();
-  }
+  explicit lock_guard(MutexType &m) : mutex(m) { mutex.lock(); }
 
   // Acquires ownership of the mutex object `m` without attempting to lock
   // it. The behavior is undefined if the current thread does not hold the
   // lock on `m`. Does not call `m.lock()` upon resource acquisition.
-  LIBC_INLINE lock_guard(LIBC_LIFETIME_BOUND MutexType &m, adopt_lock_t /* t */)
-      : mutex(m) {}
+  lock_guard(MutexType &m, adopt_lock_t /* t */) : mutex(m) {}
 
-  LIBC_INLINE ~lock_guard() { mutex.unlock(); }
+  ~lock_guard() { mutex.unlock(); }
 
   // non-copyable
   lock_guard &operator=(const lock_guard &) = delete;
diff --git a/libc/src/__support/CPP/optional.h b/libc/src/__support/CPP/optional.h
index 15f389c89627e..aed2269db1b11 100644
--- a/libc/src/__support/CPP/optional.h
+++ b/libc/src/__support/CPP/optional.h
@@ -108,13 +108,11 @@ template <typename T> class optional {
 
   LIBC_INLINE constexpr void reset() { storage.reset(); }
 
-  LIBC_INLINE constexpr const T &value() const &LIBC_LIFETIME_BOUND {
+  LIBC_INLINE constexpr const T &value() const & {
     return storage.stored_value;
   }
 
-  LIBC_INLINE constexpr T &value() & LIBC_LIFETIME_BOUND {
-    return storage.stored_value;
-  }
+  LIBC_INLINE constexpr T &value() & { return storage.stored_value; }
 
   LIBC_INLINE constexpr explicit operator bool() const {
     return storage.in_use;
@@ -124,12 +122,10 @@ template <typename T> class optional {
     return &storage.stored_value;
   }
   LIBC_INLINE constexpr T *operator->() { return &storage.stored_value; }
-  LIBC_INLINE constexpr const T &operator*() const &LIBC_LIFETIME_BOUND {
-    return storage.stored_value;
-  }
-  LIBC_INLINE constexpr T &operator*() & LIBC_LIFETIME_BOUND {
+  LIBC_INLINE constexpr const T &operator*() const & {
     return storage.stored_value;
   }
+  LIBC_INLINE constexpr T &operator*() & { return storage.stored_value; }
 
   LIBC_INLINE constexpr T &&value() && { return move(storage.stored_value); }
   LIBC_INLINE constexpr T &&operator*() && {
diff --git a/libc/src/__support/CPP/span.h b/libc/src/__support/CPP/span.h
index 58db573ef4761..9234a26d201cd 100644
--- a/libc/src/__support/CPP/span.h
+++ b/libc/src/__support/CPP/span.h
@@ -28,7 +28,7 @@ namespace cpp {
 // - No implicit type conversion (e.g. Span<B>, initialized with As where A
 //   inherits from B),
 // - No reverse iterators
-template <typename T> class LIBC_GSL_POINTER span {
+template <typename T> class span {
   template <typename U>
   LIBC_INLINE_VAR static constexpr bool is_const_view_v =
       !cpp::is_const_v<U> && cpp::is_const_v<T> &&
@@ -64,12 +64,11 @@ template <typename T> class LIBC_GSL_POINTER span {
 
   template <typename U, size_t N,
             cpp::enable_if_t<is_compatible_v<U>, bool> = true>
-  LIBC_INLINE constexpr span(LIBC_LIFETIME_BOUND U (&arr)[N])
-      : span_data(arr), span_size(N) {}
+  LIBC_INLINE constexpr span(U (&arr)[N]) : span_data(arr), span_size(N) {}
 
   template <typename U, size_t N,
             cpp::enable_if_t<is_compatible_v<U>, bool> = true>
-  LIBC_INLINE constexpr span(LIBC_LIFETIME_BOUND array<U, N> &arr)
+  LIBC_INLINE constexpr span(array<U, N> &arr)
       : span_data(arr.data()), span_size(arr.size()) {}
 
   template <typename U, cpp::enable_if_t<is_compatible_v<U>, bool> = true>
diff --git a/libc/src/__support/CPP/string.h b/libc/src/__support/CPP/string.h
index 6a3bf267bc021..1ac04c7f1f9dc 100644
--- a/libc/src/__support/CPP/string.h
+++ b/libc/src/__support/CPP/string.h
@@ -106,23 +106,16 @@ class string {
   LIBC_INLINE constexpr const char *end() const { return data() + size_; }
   LIBC_INLINE char *end() { return data() + size_; }
 
-  LIBC_INLINE constexpr const char &front() const LIBC_LIFETIME_BOUND {
-    return data()[0];
-  }
-  LIBC_INLINE char &front() LIBC_LIFETIME_BOUND { return data()[0]; }
+  LIBC_INLINE constexpr const char &front() const { return data()[0]; }
+  LIBC_INLINE char &front() { return data()[0]; }
 
-  LIBC_INLINE constexpr const char &back() const LIBC_LIFETIME_BOUND {
-    return data()[size_ - 1];
-  }
-  LIBC_INLINE char &back() LIBC_LIFETIME_BOUND { return data()[size_ - 1]; }
+  LIBC_INLINE constexpr const char &back() const { return data()[size_ - 1]; }
+  LIBC_INLINE char &back() { return data()[size_ - 1]; }
 
-  LIBC_INLINE constexpr const char &
-  operator[](size_t index) const LIBC_LIFETIME_BOUND {
-    return data()[index];
-  }
-  LIBC_INLINE char &operator[](size_t index) LIBC_LIFETIME_BOUND {
+  LIBC_INLINE constexpr const char &operator[](size_t index) const {
     return data()[index];
   }
+  LIBC_INLINE char &operator[](size_t index) { return data()[index]; }
 
   LIBC_INLINE const char *c_str() const { return data(); }
 
diff --git a/libc/src/__support/CPP/string_view.h b/libc/src/__support/CPP/string_view.h
index 1a1601c0c7ba7..aa15814b2e149 100644
--- a/libc/src/__support/CPP/string_view.h
+++ b/libc/src/__support/CPP/string_view.h
@@ -23,7 +23,7 @@ namespace cpp {
 // do the checks before invoking the methods.
 //
 // This class will be extended as needed in future.
-class LIBC_GSL_POINTER string_view {
+class string_view {
 private:
   const char *Data;
   size_t Len;
@@ -44,15 +44,6 @@ class LIBC_GSL_POINTER string_view {
         return static_cast<size_t>(End - Str);
   }
 
-  template <size_t N>
-  LIBC_INLINE static constexpr size_t
-  bounded_length(LIBC_LIFETIME_BOUND const char (&Str)[N]) {
-    for (size_t i = 0; i < N; ++i)
-      if (Str[i] == '\0')
-        return i;
-    return N;
-  }
-
   LIBC_INLINE bool equals(string_view Other) const {
     return (Len == Other.Len &&
             compareMemory(Data, Other.Data, Other.Len) == 0);
@@ -86,10 +77,6 @@ class LIBC_GSL_POINTER string_view {
   LIBC_INLINE constexpr string_view(const char *Str, size_t N)
       : Data(Str), Len(N) {}
 
-  template <size_t N>
-  LIBC_INLINE constexpr string_view(LIBC_LIFETIME_BOUND const char (&Str)[N])
-      : Data(Str), Len(bounded_length(Str)) {}
-
   LIBC_INLINE constexpr const char *data() const { return Data; }
 
   // Returns the size of the string_view.
diff --git a/libc/src/__support/CPP/stringstream.h b/libc/src/__support/CPP/stringstream.h
index a0039f2de4858..a16084c848688 100644
--- a/libc/src/__support/CPP/stringstream.h
+++ b/libc/src/__support/CPP/stringstream.h
@@ -48,9 +48,7 @@ class StringStream {
   // null terminator was not explicitly written, then the return value
   // will not include one. In order to produce a string_view to a null
   // terminated string, write ENDS explicitly.
-  [[nodiscard]] LIBC_INLINE string_view str() const {
-    return string_view(data.data(), write_ptr);
-  }
+  string_view str() const { return string_view(data.data(), write_ptr); }
 
   // Write the characters from |str| to the stream.
   StringStream &operator<<(string_view str) {
diff --git a/libc/src/__support/CPP/utility/forward.h b/libc/src/__support/CPP/utility/forward.h
index f367a34dea57f..085b3d16f999b 100644
--- a/libc/src/__support/CPP/utility/forward.h
+++ b/libc/src/__support/CPP/utility/forward.h
@@ -18,14 +18,12 @@ namespace cpp {
 
 // forward
 template <typename T>
-LIBC_INLINE constexpr T &&
-forward(LIBC_LIFETIME_BOUND remove_reference_t<T> &value) {
+LIBC_INLINE constexpr T &&forward(remove_reference_t<T> &value) {
   return static_cast<T &&>(value);
 }
 
 template <typename T>
-LIBC_INLINE constexpr T &&
-forward(LIBC_LIFETIME_BOUND remove_reference_t<T> &&value) {
+LIBC_INLINE constexpr T &&forward(remove_reference_t<T> &&value) {
   static_assert(!is_lvalue_reference_v<T>,
                 "cannot forward an rvalue as an lvalue");
   return static_cast<T &&>(value);
diff --git a/libc/src/__support/CPP/utility/move.h b/libc/src/__support/CPP/utility/move.h
index e77d64066270b..b61f723e8d4cb 100644
--- a/libc/src/__support/CPP/utility/move.h
+++ b/libc/src/__support/CPP/utility/move.h
@@ -17,8 +17,7 @@ namespace cpp {
 
 // move
 template <class T>
-LIBC_INLINE constexpr cpp::remove_reference_t<T> &&
-move(LIBC_LIFETIME_BOUND T &&t) {
+LIBC_INLINE constexpr cpp::remove_reference_t<T> &&move(T &&t) {
   return static_cast<typename cpp::remove_reference_t<T> &&>(t);
 }
 
diff --git a/libc/src/__support/macros/attributes.h b/libc/src/__support/macros/attributes.h
index a1129df936942..d5ff028634940 100644
--- a/libc/src/__support/macros/attributes.h
+++ b/libc/src/__support/macros/attributes.h
@@ -91,84 +91,4 @@ LIBC_THREAD_MODE_EXTERNAL.
 #define LIBC_NO_SANITIZE_OOB_ACCESS
 #endif
 
-// LIBC_LIFETIME_BOUND indicates that a function parameter's lifetime is tied
-// to the return value. This helps compilers detect use-after-free bugs.
-//
-// Example usage:
-//   const T &get_value(const Container &c LIBC_LIFETIME_BOUND,
-///                      const T &default_val LIBC_LIFETIME_BOUND);
-//   // Warns if temporary Container or default_val is bound to the result
-//
-// For member functions, apply after the function signature:
-//   const char *data() const LIBC_LIFETIME_BOUND;
-//   // The returned pointer should not outlive '*this'
-#if __has_cpp_attribute(clang::lifetimebound)
-#define LIBC_LIFETIME_BOUND [[clang::lifetimebound]]
-#elif __has_cpp_attribute(msvc::lifetimebound)
-#define LIBC_LIFETIME_BOUND [[msvc::lifetimebound]]
-#elif __has_cpp_attribute(lifetimebound)
-#define LIBC_LIFETIME_BOUND [[lifetimebound]]
-#else
-#define LIBC_LIFETIME_BOUND
-#endif
-
-// LIBC_LIFETIME_CAPTURE_BY(X) indicates that parameter X captures/stores a
-// reference to the annotated parameter. Warns if temporaries are passed.
-//
-// Example usage:
-//   void add_to_set(cpp::string_view a LIBC_LIFETIME_CAPTURE_BY(s),
-//                   cpp::set<cpp::string_view>& s) {
-//     s.insert(a); // 's' now holds a reference to 'a'
-//   }
-//   // Warns: add_to_set(cpp::string(), s); // temporary captured by 's'
-//
-// X can be: another parameter name, 'this', 'global', or 'unknown'
-// Multiple capturing entities: LIBC_LIFETIME_CAPTURE_BY(s1, s2)
-//
-// For member functions capturing 'this', apply after function signature:
-//   void capture_self(cpp::set<S*>& s) LIBC_LIFETIME_CAPTURE_BY(s);
-#if __has_cpp_attribute(clang::lifetime_capture_by)
-#define LIBC_LIFETIME_CAPTURE_BY(X) [[clang::lifetime_capture_by(X)]]
-#else
-#define LIBC_LIFETIME_CAPTURE_BY(X)
-#endif
-
-// LIBC_GSL_POINTER marks a class as a "view" type that points to data owned
-// elsewhere. Lifetime analysis treats it as potentially dangling when the
-// owner is destroyed. Use for types like string_view, span, or custom views.
-//
-// Example usage:
-//   class LIBC_GSL_POINTER StringView {
-//     const char *data_;
-//   public:
-//     StringView(const String& s); // Points into 's'
-//   };
-//   // Warns: StringView sv = String(); // sv points to destroyed temporary
-//
-// The attribute takes an optional type parameter (e.g., [[gsl::Pointer(int)]])
-// but it's typically omitted in libc usage.
-#if __has_cpp_attribute(gsl::Pointer)
-#define LIBC_GSL_POINTER [[gsl::Pointer]]
-#else
-#define LIBC_GSL_POINTER
-#endif
-
-// LIBC_GSL_OWNER marks a class as owning the data it manages. When an Owner
-// is destroyed, any Pointer constructed from it becomes dangling.
-//
-// Example usage:
-//   class LIBC_GSL_OWNER String {
-//     char *data_;
-//   public:
-//     ~String() { delete[] data_; }
-//   };
-//
-// Relationship: LIBC_GSL_POINTER types "point into" LIBC_GSL_OWNER types.
-// When the owner dies, pointers derived from it are considered dangling.
-#if __has_cpp_attribute(gsl::Owner)
-#define LIBC_GSL_OWNER [[gsl::Owner]]
-#else
-#define LIBC_GSL_OWNER
-#endif
-
 #endif // LLVM_LIBC_SRC___SUPPORT_MACROS_ATTRIBUTES_H

Revert "[libc] add basic lifetime annotations for support data struct…

8f7bafd

…ures (#1…" This reverts commit c0e0a33.

llvmbot added the libc label Oct 17, 2025

SchrodingerZhu merged commit 2505df0 into main Oct 17, 2025
17 of 21 checks passed

SchrodingerZhu deleted the revert-145933-libc/lifetime-preliminary branch October 17, 2025 20:35

SchrodingerZhu mentioned this pull request Oct 17, 2025

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