[all-commits] [llvm/llvm-project] 8d90a5: [clang] Add comment about misleading alloc_size ar...

[Jann via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 8d90a541537fbed7d8c2a759b4ff46192a2c436e
      https://github.com/llvm/llvm-project/commit/8d90a541537fbed7d8c2a759b4ff46192a2c436e
  Author: Jann <jannh at google.com>
  Date:   2025-04-08 (Tue, 08 Apr 2025)

  Changed paths:
    M clang/include/clang/Basic/Attr.td

  Log Message:
  -----------
  [clang] Add comment about misleading alloc_size argument names (#134899)

Attr.td names the first alloc_size argument "ElemSizeParam" and the
second optional argument "NumElemsParam"; but the semantics of how the
two-argument version is used in practice is the opposite of that.

glibc declares calloc() like this, so the second alloc_size argument is
the element size:
```
extern void *calloc (size_t __nmemb, size_t __size)
__THROW __attribute_malloc__ __attribute_alloc_size__ ((1, 2)) __wur;
```

The Linux kernel declares array allocation functions like
`kmalloc_array_noprof()` the same way.

Add a comment explaining that the names used inside clang are
misleading.



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