Address my own comments.

Author: ZeroIntensity

Doc/c-api/intro.rst

@@ -324,12 +324,15 @@ complete listing.
 
 .. c:macro:: Py_ARRAY_LENGTH(array)
 
-   Compute the length (number of elements) of a statically allocated C array at
-   compile time.
+   Compute the length of a statically allocated C array at compile time.
 
    The *array* argument must be a C array with a size known at compile time,
-   not a pointer. On supported compilers, passing a pointer will result in a
-   compilation error or otherwise produce incorrect results.
+   not on the heap. Passing a heap-allocated array will result in a compilation
+   error on some compilers, or otherwise produce incorrect results.
+
+   This is roughly equivalent to::
+
+      sizeof(array) / sizeof((array)[0])
 
 
 .. _api-objects: