tree aa77ddec85b134e783c36c010c63dab0ff514f9c
parent 71e8310be2e24d62dc8de93d0cd7ab85f02e33ad
author Wyatt Hepler <hepler@google.com> 1664308839 +0000
committer CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com> 1664308839 +0000

pw_toolchain: Implement Newlib OS interface functions

Starting in arm-none-eabi-gcc 11.3, the compiler outputs warnings if
Newlib OS interface functions are called but not implemented. A default
that returns an error is used in that case. The Newlib OS interface is
documented at https://sourceware.org/newlib/libc.html#Stubs.

Most of the Newlib OS interface functions should never be called in
Pigweed. Implement these functions but have them invoke an undefined
function to force a linker error if they are used.

In addition to implementing the OS interface, wrap a few unnecessary
Newlib functions that would otherwise cause several OS interface
functions to be linked in. Abort if these functions are called.

Change-Id: Iee0a73598b6daed175ca8328053386460b85b74a
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/112311
Commit-Queue: Wyatt Hepler <hepler@google.com>
Reviewed-by: Armando Montanez <amontanez@google.com>