Won't compile xxhash.c but will compile xxhash2.c

QtCreator won't properly build an application containing xxhash.c. If the file is renamed to xxhash2.c it will build. I will attach a sample project but this is how to recreate it:

• In QtCreator, create a new plain C++ application with default settings using qmake build system.
• Add xxhash.c and xxhash.h to the project directory from: https://github.com/Cyan4973/xxHash
• Right click project and Add Existing Items to add xxhash.c and xxhash.h to the project.
• In main.cpp, add #include "xxhash.h" and call XXH64_createState() from main (call can be to any xxhash.h function).
• Build->Rebuild All.
• Project won't link because xxhash.c wasn't compiled.
• Right click and rename xxhash.c to xxhash2.c.
• Build->Rebuild All.
• Project builds and links correctly.
• Rename xxhash2.c back to xxhash.c and project will no longer link.