[3.13] Doc/c-api/memory.rst: extend --without-pymalloc doc with ASan information (GH-136790) (#136799)

Extends the documentation for disabling pymalloc with the `--without-pymalloc` flag regarding why it is worth to use it when enabling AddressSanitizer for Python build (which is done, e.g., in CPython's CI builds).


(cherry picked from commit d19bb44)

Co-authored-by: Disconnect3d <dominik.b.czarnota@gmail.com>
Co-authored-by: Petr Viktorin <encukou@gmail.com>

Author: 3 people

Doc/c-api/memory.rst

@@ -656,6 +656,10 @@ This allocator is disabled if Python is configured with the
 :option:`--without-pymalloc` option. It can also be disabled at runtime using
 the :envvar:`PYTHONMALLOC` environment variable (ex: ``PYTHONMALLOC=malloc``).
 
+Typically, it makes sense to disable the pymalloc allocator when building
+Python with AddressSanitizer (:option:`--with-address-sanitizer`) which helps
+uncover low level bugs within the C code.
+
 Customize pymalloc Arena Allocator
 ----------------------------------
 

Doc/using/configure.rst

@@ -771,6 +771,9 @@ Debug options
 .. option:: --with-address-sanitizer
 
    Enable AddressSanitizer memory error detector, ``asan`` (default is no).
+   To improve ASan detection capabilities you may also want to combine this
+   with :option:`--without-pymalloc` to disable the specialized small-object
+   allocator whose allocations are not tracked by ASan.
 
    .. versionadded:: 3.6