The whole reason for me starting this thread was to chase down the multiple statements on the internet - going back years, and in many places - that __libc_init_array() is only for C++, while a few others contradicted this assertion but never giving any detail.
It has been achieved 😀
That's a good link Jan posted, but IIRC it contains some errors e.g.
Because Newlib is a static library with a separate object file for every function, all you need to do to replace a function is define it in your program. The linker won’t go looking for it in static libraries if it finds it in your code.
is not true in the ST context; you cannot replace a function in libc.a (or any .a file) unless that function is "weak", and ST compiled entire libc.a as non-weak. I did replace stuff like printf() (posted extensively on eevblog) and used one of the GCC tools to weaken the whole libc.a to enable replacement.
Only stuff in .o files can be replaced with own-provided functions.
IMHO, anyone expecting printf() to work without first initialising a UART is going to get into big trouble.
Q: if you wanted to initialise a UART, how would you arrange it so that calling __libc_init_array() does it? Presumably you need to list the functions which need calling, somewhere.
