[llvm] e7f422d - Add clang::lifetimebound annotation to ArrayRef constructors. (#113547)

[via llvm-commits]

Author: Haojian Wu
Date: 2024-10-28T08:38:56+01:00
New Revision: e7f422d5c2ea05704eaab2cdd67a8b1ebc55e95b

URL: https://github.com/llvm/llvm-project/commit/e7f422d5c2ea05704eaab2cdd67a8b1ebc55e95b
DIFF: https://github.com/llvm/llvm-project/commit/e7f422d5c2ea05704eaab2cdd67a8b1ebc55e95b.diff

LOG: Add clang::lifetimebound annotation to ArrayRef constructors. (#113547)

This enables clang to detect more dangling issues.

```
ArrayRef<int> func() {
   constexpr int array[] = {...}; // oops, missing the static
   return array; // return a dangling reference, bomb.
}
```

See #113533.

Added: 
    

Modified: 
    llvm/include/llvm/ADT/ArrayRef.h
    llvm/include/llvm/Support/Compiler.h

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/ADT/ArrayRef.h b/llvm/include/llvm/ADT/ArrayRef.h
index bf6b55923b84ba..1139fd81cbd07f 100644
--- a/llvm/include/llvm/ADT/ArrayRef.h
+++ b/llvm/include/llvm/ADT/ArrayRef.h
@@ -70,15 +70,16 @@ namespace llvm {
     /*implicit*/ ArrayRef(std::nullopt_t) {}
 
     /// Construct an ArrayRef from a single element.
-    /*implicit*/ ArrayRef(const T &OneElt)
-      : Data(&OneElt), Length(1) {}
+    /*implicit*/ ArrayRef(const T &OneElt LLVM_LIFETIME_BOUND)
+        : Data(&OneElt), Length(1) {}
 
     /// Construct an ArrayRef from a pointer and length.
-    constexpr /*implicit*/ ArrayRef(const T *data, size_t length)
+    constexpr /*implicit*/ ArrayRef(const T *data LLVM_LIFETIME_BOUND,
+                                    size_t length)
         : Data(data), Length(length) {}
 
     /// Construct an ArrayRef from a range.
-    constexpr ArrayRef(const T *begin, const T *end)
+    constexpr ArrayRef(const T *begin LLVM_LIFETIME_BOUND, const T *end)
         : Data(begin), Length(end - begin) {
       assert(begin <= end);
     }
@@ -103,7 +104,8 @@ namespace llvm {
 
     /// Construct an ArrayRef from a C array.
     template <size_t N>
-    /*implicit*/ constexpr ArrayRef(const T (&Arr)[N]) : Data(Arr), Length(N) {}
+    /*implicit*/ constexpr ArrayRef(const T (&Arr LLVM_LIFETIME_BOUND)[N])
+        : Data(Arr), Length(N) {}
 
     /// Construct an ArrayRef from a std::initializer_list.
 #if LLVM_GNUC_PREREQ(9, 0, 0)
@@ -113,7 +115,8 @@ namespace llvm {
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Winit-list-lifetime"
 #endif
-    constexpr /*implicit*/ ArrayRef(std::initializer_list<T> Vec)
+    constexpr /*implicit*/ ArrayRef(
+        std::initializer_list<T> Vec LLVM_LIFETIME_BOUND)
         : Data(Vec.begin() == Vec.end() ? (T *)nullptr : Vec.begin()),
           Length(Vec.size()) {}
 #if LLVM_GNUC_PREREQ(9, 0, 0)

diff  --git a/llvm/include/llvm/Support/Compiler.h b/llvm/include/llvm/Support/Compiler.h
index 591e7647795bb2..f9c57b89f1f033 100644
--- a/llvm/include/llvm/Support/Compiler.h
+++ b/llvm/include/llvm/Support/Compiler.h
@@ -413,6 +413,12 @@
 #define LLVM_GSL_POINTER
 #endif
 
+#if LLVM_HAS_CPP_ATTRIBUTE(clang::lifetimebound)
+#define LLVM_LIFETIME_BOUND [[clang::lifetimebound]]
+#else
+#define LLVM_LIFETIME_BOUND
+#endif
+
 #if LLVM_HAS_CPP_ATTRIBUTE(nodiscard) >= 201907L
 #define LLVM_CTOR_NODISCARD [[nodiscard]]
 #else