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c memory-management makefile linker libc

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Accepted Answer Available
Accepted Answer
May 26, 2026 Score: 5 Rep: 235,129 Quality: High Completeness: 50%

This can happen if you have other includes before #define GNUSOURCE.

Make sure this macro appears first before any file is included. For example, this causes an implicit declaration warning for mremap:

#include 
#include 
#define GNUSOURCE
#include

While this does not:

#define GNUSOURCE
#include 
#include 
#include