To enable Dynamic Allocation Functions, features from ISO/IEC TR 24731-2:2010, the macro __STDC_WANT_LIB_EXT2__ hs to be defined to 1 before to the stdio.h header is included. diff -urN hdf5-1.14.5/src/H5private.h.orig hdf5-1.14.5/src/H5private.h --- hdf5-1.14.5/src/H5private.h.orig 2024-09-30 18:07:53.000000000 +0200 +++ hdf5-1.14.5/src/H5private.h 2024-10-29 17:09:55.936592100 +0100 @@ -20,6 +20,9 @@ #ifndef H5private_H #define H5private_H +#define __STDC_WANT_LIB_EXT2__ 1 // define for TR 24731-2:2010 extensions (e.g., vasprintf) +#define _GNU_SOURCE + #include "H5public.h" /* Include Public Definitions */ #include