On 06.07.26 20:11, Tristan Partin wrote:
On Mon Jul 6, 2026 at 6:10 PM UTC, Tristan Partin wrote:
Postgres memory allocators, by default, ERROR out on memory allocation
failures. An ERROR leads to a longjmp, which means that the caller of
the allocator will never see a NULL return value. We can explicitly let
the compiler know about this behavior by adding the returns_nonnull
attribute to the allocators that follow this behavior. Postgres does
support _extended versions of some of the allocators that take a flaks
argument. The caller can provide the MCXT_ALLOC_NO_OOM flag to these
allocators to request that they return NULL on allocation failure
instead of ERROR-ing out. The _extended allocators cannot be marked as
returns_nonnull because of that.
By using returns_nonnull, we can help the compiler to optimize call
sites.
Your patch marks palloc_mul_extended() as pg_attribute_returns_nonnull,
which seems incorrect per the above description.
Also, per the discussion in the counted_by thread, lets put these new
attributes in their more correct position in front of the declaration.
(Note that several of these already use pg_nodiscard, which is also an
attribute.) That way we can also use the MSVC annotation _Ret_notnull_.
